A & P 1 lecture notes 1-9 (Final Exam)

Acids, bases, and salts

o Acids, bases, and salts - The maintenance of a constant internal environment within the body, or homeostasis, is an important aspect of life. As an example, the pHof different fluids and substances within the body must be contained within narrow limits in order to maintain equilibrium and ensure that the body's systems work effectively. Conditions that are too acidic or alkaline can damage the tissues of the body. o pH - The electrical charge of molecules found within the body is changeable based on the availability of certain ions in the immediate environment. If the charge of a molecule changes, then so will its interactivity with other molecules. This can have a drastic effect upon the functionality of a cell or process. pH is a measure of the concentration of certain ions found in a solution, and is used as an indicator of the acidity or alkalinity of a substance. The pH of extracellular fluid must stay within the range of 6.8-7.8 in order to be compatible with life (the pH of blood has a narrow range of 7.35-7.45). o pH scale - The pH scale measures how acidic or basic a substance is by measuring the concentration of hydrogen ions (H+) within it. The pH scale is a logarithmic scale ranging from 0-14. This means that there is a tenfold difference in hydrogen ion concentration between each number present on the scale. So, for example, lemon juice (pH 2) is ten times more acidic than grapefruit juice (pH 3). o Neutral - A pH of 7 is considered neutral: pH 7 denotes an equal balance of hydrogen ions, also called protons (H+), and hydroxide ions (OH-), which is why it is described as neutral. Pure water is neutral as it dissociates into an equal balance of H+ and OH-.An increase in H+, or decrease in OH-, lowers the pH. A decrease in the H+ concentration and an increase in the OH- concentration results in a higher pH. o Acid - An acid is a substance with a pH of less than 7. It contains more hydrogen ions compared with hydroxide ions. The more acidic a substance is, the lower its pH will be, i.e., the strongest acid will have a pH approaching 0. One of the strongest acids found in the body is hydrochloric acid, which has a pH of 2. o Base - A base is a substance with a pH of more than 7. It contains more hydroxide ions compared with hydrogen ions. The more basic a substance is, the higher its pH will be. The strongest alkali will have a pH approaching 14. - The pH scale helps us to understand the relative concentration of hydrogen ions in the substances of the body, such as stomach acid and saliva. o Acids: - An acid is a substance with a pH of less than 7. This pH range occurs in a solution as a result of a higher concentration of positively charged hydrogen ions compared with negatively charged hydroxide ions. The acidity of a substance is determined by its ability to dissociate, or separate, into hydrogen ions and an anion. Weak acids have a higher pH, because they only partially dissociate, resulting in a lower concentration of hydrogen ions in solution. Strong acids have a lower pH because they fully dissociate and have a higher concentration of hydrogen ions. Acid + Water → Hydrogen ion + anionAn example of a strong acid is hydrochloric acid, which forms part of the gastric juice found in the stomach. When it reacts with water, each hydrochloric acid molecule completely dissociates into a hydrogen ion and a chloride anion. Each resulting hydrogen ion carries a single positive charge that can be donated towards other chemical reactions. Hydrochloric acid (HCl) + water → H+ + Cl- Acids are, therefore, known as proton donors. o Properties of acids Have a pH of less than 7. Contain hydrogen ions (H+). Proton donors. o Bases: - A base is a substance with a pH greater than 7. This is because bases contain a higher concentration of negatively charged hydroxide ions, compared with positively charged hydrogen ions.Negatively charged hydroxide anions are composed of an oxygen atom connected by a covalent bond to a hydrogen atom. In general, the more basic, or alkaline a substance is, the higher its pH will be. An example of a strong base is sodium hydroxide, which is not normally found in the body. When sodium hydroxide dissolves in water, it dissociates into positively charged sodium cations, and hydroxide anions.Sodium hydroxide (NaOH) + Water → OH- + Na+ In an acidic solution, each hydroxide ion produced is able to bind to a proton present in the solution, forming a neutral water molecule. This reduces the concentration of hydrogen ions of the immediate environment, and returns the pH level of the solution to neutral. Bases are, therefore, known as proton acceptors. o Properties of bases Have a pH of more than 7. Contain hydroxide ions (OH-). Proton acceptors. o Salts - A salt is an electrically neutral ionic compound formed of equal numbers of anions, negatively charged ions, and cations, positively charged ions. Unlike acids or bases, salts do not contain hydroxide or hydrogen ions. Salts are formed when an acid reacts with a base: this is known as a neutralization reaction.Acid + Base → Salt + WaterFor example, hydrochloric acid reacts with the base sodium hydroxide to produce the neutral salt sodium chloride, plus a water molecule.Sodium hydroxide (NaOH) + Hydrochloric acid (HCl) → Sodium chloride (NaCl) + Water (H2O)When a salt is dissolved in water, it dissociates into its component ions, such that sodium chloride dissociates into a sodium ion, and a chloride ion. These salts that ionize in water are known as electrolytes, and are able to conduct electricity. As electrolytes, salts are essential for muscle contraction and the transmission of nerve impulses. They also provide essential chemical elements in intracellular and extracellular fluids such as blood, lymph, and interstitial fluid. o Properties of salts Created when acids neutralize bases. Contain cations and anions. o Buffer systems - Cells in the body are extremely sensitive to changes in pH. As homeostatic balance must be maintained, it is very important that pH is tightly controlled. To do this, the body uses buffer systems. A buffer is a chemical or group of chemicals that resist changes in pH. When ions that influence pH (hydrogen ions and hydroxide ions) are added to a system, buffers act to reduce the availability of these ions, and, therefore, minimize any change in pH. An important physiological buffer is the carbonic acid-bicarbonate system. For more information, see 'Fluid, Electrolyte, and Acid-Base Balance: pH, Buffer Systems, and Compensation'.

In movements possible around a synovial joint, __________ describes the movement of bringing two bones closer together 1. hyperextension 2. adduction 3. circumduction 4. flexion 5. abduction 6. extension

4. flexion

The function of the rotator cuff muscles is to hold the head of the humerus within the acromion fossa of the scapula. 1. true 2. false

2. false

The insertion of a muscle is that end which during contraction, stays relatively motionless. 1. true 2. false

2. false

SUPRARENAL GLANDS

The suprarenal glands (adrenal glands) are small, yellow glands located superior and medial to the kidneys and they and the kidneys lie outside the peritoneum. For this reason, they and the kidneys are considered to be retroperitoneal (not in the abdominal cavity but just outside it). The suprarenal glands have an inner medulla region and an outer cortex which arise from different tissues embryologically and function separately. Functions of the suprarenal glands follow regulate mineral homeostasis regulate glucose homeostasis promotes start of puberty triggers "fight or flight" response Gross Anatomy of Suprarenal Glands Right suprarenal gland is pyramid shaped and lies just posterior to the inferior vena cava and rests on the superior aspect of the right kidney with its superior surface in contact with the diaphragm. Left suprarenal gland has a flat appearance and rests on the left kidney making contact with the left crus of the diaphragm and the pancreas. A crus is a tendinous structure extending inferiorly from the diaphragm to attach to the vertebral column and form a tether for muscular contraction. (crus - Latin for leg) Microanatomy of Suprarenal Glands Suprarenal glands consist if s thin inner dark red or grayish medulla and a yellowish outer cortex which forms the majority of the gland. Cortex structure Capsule: thick outer covering containing rich blood supply, function is for protection as well as source of rich blood supply. Zona glomerulosa: outermost zone of cortex which secretes mineralocorticoids to regulate mineral homeostasis. Zona fasciculate: middle and widest of three zones, makes and secretes glucocorticoids which regulate glucose metabolism. Zona reticularis: innermost zone which synthesizes and secretes androgens which have masculinizing effects. Some low levels of estrogen are also secreted. Medulla structure Suprarenal medulla composed of basophilic secretory chromaffin cells which secrete noradrenaline (norepinephrine) and adrenalin (epinephrine) into the blood. Hormones of the Suprarenal Cortex Mineralocorticoids: aldosterone helps control blood volume and blood pressure by promoting reabsorption od sodium and water and secretion of potassium by the kidney tubules. Glucocorticoids such as cortisol, corticosterone and cortisone control carbohydrate metabolism to increase blood sugar. They also stimulate gluconeogenesis (glucose formation) in the liver, breakdown of muscle protein to amino acids, stimulation of lipolysis in adipose tissue and conserve glucose by inhibiting its uptake by muscle and adipose tissue. They also increase circulating glucose and increase ATP supply and also increase blood pressure by enhancing vasoconstriction. High glucocorticoid levels can also suppress immune response and suppress inflammatory response by inhibiting white blood cells and suppress tissue repair as well. Androgen secretion by zona reticularis are insignificant in effect in males as they are masked by androgen secretion by the testes but do play a role in female libido (sexual drive). Adrenal androgens also play an important role in puberty promoting growth spurts and stimulating growth of axillary and pubic hair. Control of Aldosterone Secretion Aldosterone secretion is controlled by the renin-angiotensin-aldosterone pathway by the following steps: Fall in blood pressure in afferent arterioles i=of kidneys causes juxtaglomerular cells to release renin. Renin converts angiotensinogen in plasma to angiotensin I Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE). Angiotensin II targets smooth muscle cells in walls of arteriole causing vasoconstriction causing blood pressure to increase. Angiotension II also targets adrenal cortex to stimulate cells of zona glomerulosa to secrete aldosterone into the blood. Aldosterone then targets kidney to increase reabsorption of sodium ions and water back into blood and increase loss of potassium ions and hydrogen ions in the urine. As more water is reabsorded back into blood, blood volume rises causing blood pressure to increase. Control of Glucocorticoid Secretion Glucocorticoid secretion regulated by a negative feedback mechanism. Decreased levels of glucocorticoid levels in blood causes hypothalamic neurosecretory cells to secrete corticotropin-releasing hormone into hypophyseal blood stream which targets corticotroph cells on anterior pituitary to release adrenocorticotrophin hormone (ACTH) into blood which then causes zona fasciculate to synthesize and release glucocorticoids. Control of Androgen Secretion Not enough known about control of secretion of androgens by suprarenal glands. Hormones of the Suprarenal Medulla Chromaffin cells of adrenal medulla function like postganglionic sympathetic neurons except they lack axons and release the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline) instead of neurotransmitters. These hormones are catecholamines, hormones that help regulate the sympathetic division of the autonomic nervous system. When we perceive a "flight or fight" situation, adrenaline and noradrenalin are secreted and increase blood flow by increasing heart rate, raising blood pressure by vasoconstricting blood flow to digestive organs and skin and increasing blood flow to skeletal muscles and heart. All of these actions prepare the body to either stand and fight or flee a life threatening or dangerous situation.

How many molecules of ATP are produced by the catabolism of one creatine phosphate molecule? 1. 1 2. 5 3. 2 4. 3 5. 4

1. 1

what is the largest bone of the sternum? 1. diploid process 2. body 3. manubrium

2. body

Which tarsal bone forms the heel on the foot? 1. lateral cuneiform 2. talus 3. navicular 4. cuboid 5. calcaneus

5. calcaneus

Divisions of Nervous System

Brain Subdivisions The brain (see Nervous System, Brain Module, Brain topic on subject area list on left in online text) consists of three subdivisions known generally from their embryonic origin; the forebrain, midbrain and hindbrain. Brain Brain is formed structurally into four main parts: the brainstem, cerebellum, diencephalonand cerebrum and is covered by layers of fascia called the meninges. The gray matter is located on the outside of the brain and is composed of neuronal cell bodies. The white matter is located in the middle and is formed of myelinated neuronal axons and forms most of the brain making connections with the spinal cord and cranial nerves. Brainstem is subdivided into the medulla oblongata, pons and midbrain. Medulla oblongata is the most inferior part of the brainstem and is continuous with the spinal cord. It extends upward from the foramen magnum to the pons where its border is marked by a groove. Internally the medulla oblongata contains the nuclei for the cardiac center which governs heart rate and force of contraction, the respiratory center which regulates respiratory movements, the vasomotor center which regulates blood vessel diameter, the special senses nuclei for cranial nerves IX (gustatory), VIII (cochlear) and VIII (vestibular) reside here and the cranial nerve nuclei for the IX (Glossopharyngeal), X (Vagus), XI (Accessory) and XII (Hypoglossal) also reside in the medulla oblongata. Pons is a bulge located on the anterior surface of the brainstem in front of the cerebellum and forms the origin of the middle cerebellar peduncles. Fibers from the cerebrum going to the cerebellum reside here along with ascending fibers to the thalamus and fibers that connect the two lobes of the cerebellum. Midbrain is the smallest part of the brainstem and located on the posterior portion of the pons. Nuclei for cranial nerves V (trigeminal), VI (abducens), VII (facial) and VIII (vestibulocochlear) reside here. Cerebellum Cerebellum is located on posterior part of cranium and consists of two hemispheres. It controls muscle coordination, maintains balance and equilibrium and fine tunes movements at the conscious and subconscious levels. It is separated from the pons and medulla oblongata anteriorly by the fourth ventricle. The cerebellum sends information about movement to the thalamus helping to smooth and coordinate complex movements. Diencephalon The diencephalon lies between the brainstem and the cerebrum surrounding the third ventricle and is formed by the thalamus, hypothalamus and epithalamus. The thalamus lies beneath the cerebrum and forms most of the diencephalon and contains sensory input from the spinal cord and brainstem to send to the cerebral cortex. It also receives motor fibers from the cerebellum to relay to the information to the cerebral cortex. It also contains Intercerebellar fibers which relay information via fibers from one area of the cerebral cortex to another area. The hypothalamus is a small area that lies inferior and lateral to the anterior aspect of the third ventricle. It is constricted anteriorly by the optic chiasma and it inferior portion is stretched into a hollow stalk (infundibulum) that attaches to the pituitary gland. The thalamus consists of many neurosecretory cell bodies which carry out a number of functions such as the secretion of releasing and inhibiting hormones which either stimulate or inhibit the release of hormones from the anterior pituitary gland. Neurons from the hypothalamus also produce hormones causing release of hormones from the posterior pituitary gland. Other important functions of the hypothalamus include controlling feelings of hunger and fullness, water balance and thirst and sleep/wake cycle. Epithalamus The epithalamus is a small area of tissue that lies posterior to the third ventricle and contains the habenular nuclei. The pineal gland protrudes from the posterior aspect. The habenularnuclei are involved in olfaction and the pineal gland is an endocrine gland that releases melatonin to produce the body's internal clock which makes one sleepy and informs the body it's time to wake up from sleep. Insula - smallest lobe of brain and located deep in the cerebrum, deep to the parietal and temporal lobe. It functions in taste and hearing and visceral sensations. Each cerebral hemisphere contains prominent gyri (bumps) and sulci (grooves) which vary amongst individuals but several main features are similar from one individual such as the longitudinal fissure which divided the cerebrum into right and left hemispheres. The central sulcus descends downwards and divides the frontal and parietal lobes and the parietal-occipital sulcus divides the parietal and occipital lobes. On the side of the brain, the lateral sulcus divides the temporal lobe from the frontal lobe above. The majority of the cerebrum is formed of white matter and composed of myelinated axons that form tracts which connect the cerebrum to other parts of the central nervous system. There are three types of tracts defined by the areas they connect. Association tracts: connect gyri within the same hemisphere Commissural tracts: connect gyri in different hemispheres Projection tracts: connect gyri with different areas of CNS The corpus callosum serves to connect both cerebral hemispheres. There is some separation of function in the two cerebral hemispheres: left - language skills right - non-verbal skills such as music, math and abstract thinking. Brain Cavities and Canals The brain cavities and canals are known as ventricles and are filled with cerebrospinal fluid which helps cushion the brain and spinal cord upon impact. The blood-brain barrier - consists of endothelial cells tightly surrounding brain capillariessothat substances getting to the brain cells are "screened" by these cells before letting them pass to brain. Some lipid-soluble substances such as caffeine, nicotine, alcohol, barbiturates, heroin and other lipid-soluble drugs get through to the brain very quickly and hence have a very quick effect on brain function.

Commonly Abused Drugs:

Stimulants: Caffeine - found in coffee, tea, chocolate and many soft drinks. Low doses stimulate neurons of the cerebral cortex to cause increased alertness and restlessness. Nicotine - found in tobacco and mimics the effects of the neurotransmitter, acetylcholine. This c auses an increase in secretion of adrenalhormonesstimulating increase in heart rate and blood pressure. Addiction can occur making it difficult to stop smoking. Amphetamines - synthetic chemicals resembling dopamine and norepinephrine that normally stimulate the pleasure center. Small doses make an individual more alert but over time brain begins producing less of its own natural signaling molecules and this tolerance causes a need to increase dosage to get the same effect. When amphetamines wear off, the user "crashes" in a state of exhaustion. Cocaine - stimulates pleasure centers by blocking reabsorption of dopamine and norepinephrine (normally released at synapses). Receptors are stimulated over a long period of time with increased heart rate and blood pressure and an increased sexual appetite. But, as stimulating molecules diffuse away from synapse, normal cell production of signaling molecules is not enough to satisfy the hypersensitive cells and it is impossible to now experience pleasure. Long term use can cause heart problems, weight loss and sleep deprivation. On some occasions, a single time user has been known to die of heart failure. Granular cocaine is inhaled or snorted but crack cocaine may be burned and the smoke is inhaled. Crack cocaine is thought to be the most serious of all drug problems. Sedatives, Hypnotics and Antianxiety Drugs: Alcohol - goes across the plasma membrane quickly. Food tends to decrease alcohol uptake and females tend to become intoxicated more quickly than males because of gender-related enzyme differences. Alcohol in increased amount causes powerful psychoactive experiences and long-term use can destroy nerve cells and damage the brain, heart and liver. Cirrhosis of the liver is permanent scarring and replacement of normal liver cells with scar tissue. Barbiturates - prescribed medically to help control epileptic seizures and induce relaxation. Can be abused as downers to cause extreme drowsiness and impaired judgement. Methaqualone, also known as Quaalude, can be prescribed as a sedative but can be abused. Analgesics - The body produces its own analgesics or pain relievers such as endorphins andenkephalins. Narcotic analgesics such as codeine, morphine and heroin are allopioids because they come from opium. After addiction on opioids, attempts to stop cause fever, chills, hyperactivity and anxiety, vomiting, cramping and diarrhea. HallucinogensLSD - affects activity of brain hormone, serotonin. Can cause increase in heart rate, blood pressure as well as vivid hallucinations and psychotic episodes.Marijuana - comes from the plant Cannabis sativa, and its main active ingredient in tetrahydrocannibinol or THC. In low doses it acts as a depressant, slowing motor activity and causing mild euphoria. It can also produce disorientation, extreme anxiety and paranoid delusions and can affect performance of complex tasks such as driving or studying. DeliriantsPCP - can cause toxic psychosis or delirium and trigger dangerous outbursts of violent behavior.Inhalents - substances that produce vapors which when inhaled cause psychoactive episodes. Cleaning fluids, butane, airplaneglue, amyl nitrate (poppers) and aerosal gases are examples, and all can havetoxic effects on the liver, kidneys, respiratory system and heart. Hepatitus, irregular heartbeat and brain damage can result.

What is the origin of the semispinalis capitis muscle?

spinous processes of T3 - T6 vertebra

Which muscles form the calcaneal tendon, also known as the Achilles tendon?

gastrocnemius, soleus

Ruffini corpuscle

- A Ruffini corpuscle, or a type II cutaneous mechanoreceptor, is an elongated, encapsulated receptor located in the dermis. - Found in the hands and soles of feet, they respond to stretching, often associated with the movement of limbs

Dermal root sheath

- A dense region of the dermis that surrounds the hair. - The bulb is the site of hair growth. Within the bulb there are several structures not found in the other parts of the hair

Hair root plexus

- A rapidly adapting, free nerve ending wrapped around a hair follicle is called a hair root plexus. Movement of hair stimulates the associated hair root plexus. - Found in hairy skin.

Epithelial membranes

- Epithelial membranes are classified as mucous membranes, serous membranes, or cutaneous membranes. They consist of an epithelium overlying a connective tissue layer.

Chondroitin sulfate

- Present in the skin, blood vessels, and cartilage, chondroitin sulfate has supportive and adhesive properties, providing resistance to compression.

Radiation

- Radiation is the transfer of heat between two objects that are not in contact, e.g., as the body's average temperature is around 96.8 °F and therefore often warmer than its surroundings, it radiates heat into the external environment. The more surface area of the skin that is exposed, the more heat will be radiated. Vasodilation brings more warm blood to the surface of the skin, thus increasing heat loss to the external atmosphere via radiation. Vasoconstriction has the opposite effect.

Many muscles operate together to produce the same movement and are termed ""synergists". 1. true 2. false

1. true

Rigor mortis is caused by the lack of ATP. 1. true 2. false

1. true

From a functional point of view, what type of joint allows free movement such as the knee or shoulder joint? 1. diarthroses 2. amphiarthroses 3. synarthroses

1. diarthroses

Which of the following muscles form the deep layer of both the male and female pelvic floor? 1. levator ani, coccygeus 2. coccygeus, deep transverse perineal 3. bulbospongiosus, levator ani 4. coccygeus, bulbospongiosus

1. levator ani, coccygeus

What is the insertion for the masseter muscle? 1. temporal bone 2. zygomatic bone 3. mandible (coronoid process) 4. maxilla bone 5. nasal bone

3. mandible (coronoid process)

What is the action of the deltoid muscle? 1. adducts the arm 2. abducts the arm 3. laterally rotates the arm 4. medially rotates the humerus 5. flexes the arm

2. abducts the arm

Which of the following muscles act to extend the knee? 1. semimembranosus, sartorius 2. vastus medialis, rectus femoris 3. vastus medialis, biceps femoris 4. rectus femoris, semimembranosus 5. biceps femoris, sartorius

2. vastus medialis, rectus femoris

Which one of the following pairs of ribs is considered to be false? 1. 1st 2. 6th 3. 3rd 4. 9th

4. 9th

The origin of the splenius capitus includes which of the following vertebrae? 1. T8, C5 2. C7, T8 3. C5, T1 4. C7, T1 5. C1, T1

4. C7, T1

The space between the end of a motor neuron and where it abuts against the muscle cell membrane is called what? 1. cross bridge 2. axon 3. Z-line 4. synapse

4. synapse

What is the origin of the zygomaticus minor muscle? 1. modiolus 2. lesser wing of sphenoid 3. superior tarsus (eyelid) 4. zygomatic bone

4. zygomatic bone

Bone Remodeling Over Time

During growth years, as the long bones such as the femur grow wider, osteoclasts dissolve bone inside the shaft and osteoblasts lay down new bone on the outside of the shaft. This permits bone to grow in width without accumulating excess weight. In later years, especially in women, osteoporosis may set in which bone loss of Calcium may occur faster thereby weakening bones of the hip and spine. Exercise may help to counter bone loss of mass especially in the younger years.

Endocrine System

Endocrine system consists of collection of glands and specialized cells spread throughout the body that secrete hormones into the bloodstream. There are a number of endocrine glands and they secrete chemical messengers (hormones) that circulate in the blood and act upon target cells to cause changes in cell function which have a role in control of bodily functions. Speed of response to endocrine system's secretions is slower than the body responds to a nervous system response but effect of hormones is generally longer lasting than that of a nervous signal. TYPES OF GLANDS Exocrine glands secrete non-hormone products via ducts to the outside of the body such as sweat glands, mucous glands, digestive glands, sebaceous glands or oil glands. (Inside of digestive tract still considered outside the body mass) Endocrine glands are ductless, formed of hollow spherical follicles lined with secretory cells with follicles surrounded by an extensive capillary network. Hormones secreted into interstitial fluid and diffue into blood capillaries to be transported to target organ, tissue or cells located usually at a distance from the gland. Examples are pituitary gland, pineal gland, thyroid, parathyroid and adrenal glands. Functions of the endocrine system are many and they should be reviewed in your online text in the Introduction section. HORMONES Actions of hormones can be classified by how far they travel from their site of secretion and the target cells they act on as follows: Endocrine actions: hormones distributed in blood and bind to target cells away from their site of secretion Paracrine actions: hormones that act locally by diffusing to nearby target cells Autocrine actions: hormones that act on the same cell that produces them CLASSIFICATION OF HORMONES Hormones are classified as either water-soluble hormones or lipid-soluble hormones and because of their chemical structure exert their effects differently. Water-soluble hormones: amino acid-based and other non-steroid hormones which can circulate freely in the blood but cannot diffuse across the lipid bilayer cell membrane. They need to bind to a cell surface receptor in order to cause the desired effect in the target cell. Types of water-soluble hormones consist of amines, peptides and eicosanoids. Some examples of amine hormones include epinephrine, norepinephrine, dopamine, histamine and serotonin Some examples of peptide hormones include antidiuretic hormone (ADH), oxytocin, human growth hormone and insulin. Some examples of eicosanoid hormones include prostaglandins and leukotrienes Lipid-soluble hormones: lipid-soluble hormones can diffuse through lipid bilayer of cell membrane but because they are insoluble in water, need a transport protein to circulate them in the blood stream. Types of lipid-soluble hormones include the steroid hormones and thyroid hormones. Steroid hormones are derived from cholesterol and include the gonadal and adrenocortical hormones such as testosterone, estrogen, progesterone, aldosterone, cortisol, androgen and calcitriol. Thyroid hormones are formed from iodine and the amino acid tyrosine and are synthesized in the thyroid. Thyroxine (T4) and triiodothyronine (T3) are the thyroid hormones (T4 and T3 refer to the number of iodine molecules in each hormone.) Gases The primary gas that has been verified as having hormonal effects in the human body is nitric oxide (NO) which acts as a neurotransmitter and as a local hormone secreted from the endothelial cells of blood vessel walls by nitric oxide synthase enzymes. ACTIONS OF WATER SOLUBLE HORMONES Review in your online text in the Hormones section, the ACTIONS OF WATER SOLUBLE HORMONES sequence of cascading events from the binding of a water-soluble hormone to a cell surface receptor to its last action in the sequence of activating phosphorylating proteins. You should be familiar with the terms and actions of hormone-receptor complex, G protein, adenylate cyclase, conversion of ATP to cAMP (cyclic AMP), secondary messenger, protein kinases, and phosphorylated kinases. ACTIONS OF LIPID SOLUBLE HORMONES Review in your online text in the Hormones section, the ACTIONS OF LIPID SOLUBLE HORMONES to understand differences from water-soluble hormone action. You should understand role of hormone-receptor complex on the transcription factor (binding to DNA is produce messenger RNA (mRNA) and its role on translation (creation of new proteins from mRNA). HORMONE INTERACTION Ways in which hormones may act with each other are listed below. Permissive hormones: can act as secondary hormones, promoting effect of a primary hormone. Synergistic hormones: when two hormones work together to cerate an effect greater than if one were to act alone. Agonist hormones: when a single hormone forms a hormone-receptor complex which triggers a cascade of events inside the target cell. Antagonist hormones: when one hormone can block the action of another hormone by binding to the receptor. General rule of thumb - target cell activation by a hormone is dependent upon (1) blood levels of hormone, (2) number of specific receptors on target cell and (3) how strong is the binding (affinity) of the hormone-receptor bond.

Compartments

Layers of fascia separate muscles in functionally related groups into compartments and form septa (tissue walls) between them. Found a lot in limb musculature and compartments prevent the spread of infection and helps to provide pressure around veins to help blood to return to the heart.

Other Endocrine Glands and Tissues

Pineal Gland: pea sized gland located in middle of the brain at the midline. Formed of cells called pinealocytes which secrete melatonin. Melatonin levels in blood stream are low during the day and high at night. Melatonin promotes sleep and regulates the sleep-wake cycle. Melatonin production is regulated by light and is linked to the circadian rhythm (24 hour clock) which can regulate the cycle of body temperature. Thymus: is quite large in newborns and is necessary for the normal development of the immune system, especially the T lymphocyte maturation. Without a thymus, a bubble-boy syndrome can develop in which there is no ability to fight off infection. Gastrointestinal tract: the GI tract contains many enteroendocrine cells which are similar to neurons and they secrete a number of hormones as indicated below: Gastrin: synthesized by G cells in stomach, duodenum and pancreas with a target of chief cells, parietal cells and smooth muscle in the stomach to stimulate secretion of gastric juice (hydrochloric acid) and increases movement of the stomach. Gastric inhibitory peptide: polypeptide secreted by K cells of duodenum and jejunum with a target of the stomach and action to inhibit secretion of hydrochloric acid, inhibits stomach motility and stimulates insulin production. Glucose-dependent insulinotropic peptide: polypeptide hormone secreted by K clls on the duodenum and jejunum with a target of pancreatic beta cells and triggers insulin release. Cholecystokinin: peptide secreted by I cells in mucosa of the duodenum with a target of the pancreas and gallbladder. In the pancreas, it stimulates secretion of pancreatic juice and gives us the feeling of fullness after eating. In the gallbladder, it relaxes the hepaticopancreatic sphincter to release bile into the duodenum. Secretin: peptide hormone secreted by S cells of duodenum with a target of the pancreas, liver and stomach. In the pancreas, it stimulates secretion of bicarbonate-rich pancreatic juice. In the liver, it increases bile secretions and in the stomach, it inhibits secretory activity of the stomach. Ghrelin: peptide hormone secreted by cells lining the fundus of the stomach and epsilon cells of the pancreas. It targets the brain and stimulates gastric activity. Placenta The placenta is formed of a fetal portion which arises from the chorion, one of the extraembryonic membranes and a maternal portion composed of a part of the endometrium. Hormones of placenta follow: Human chorionic gonadotropin: targets the corpus luteum of the ovaries and prevents breakdown of the corpus luteum so it maintains the production of estrogen and progesterone for pregnancy. Progesterone: targets uterus and mammary glands with an action to support the endometrium and suppress contractility of uterine smooth muscle to maintain pregnancy. It also inhibits lactation during pregnancy and inhibits LH and FSH secretion by the anterior pituitary preventing ovulation during pregnancy. Estrogens: estrogen levels increase toward end of gestation and target uterus and mammary glands to prepare uterus for childbirth, mammary glands for milk production and they also inhibit LH and FSH secretion from the anterior pituitary. Human chorionic somatomammotropin: targets mammary glands to prepare for lactation. Relaxin: secreted by corpus luteum and targets pubic symphysis to promote flexibility and to dilate the uterine cervix during labor. Kidneys Kidneys secrete three hormones: Erythropoietin: glycoprotein that targets red bone marrow and causes an increase in red blood cell production. Calcitriol: active form of vitamin D synthesized by kidney tubules and targets the intestines to increase absorption of calcium and phosphorous from digested food. Renin: also called angiotensionogenesis and secreted by the juxtaglomerular cells of the kidney in response to decreased arterial blood pressure and targets the bloodstream and kidneys to cause vasodilation of arterioles and suprarenal cortex to produce aldosterone. Heart Atrial natriuretic peptide or factor is secreted by cardiac muscles and targets suprarenal glands, kidneys, blood vessles and adipose tissue. The suprarenal glands inhibits aldosterone release therby decreasing sodium reabsorption and water retention and decreases blood pressure. In the kidneys, is causes vasodilation of glomerular arteries increasing sodium and water los and causes vasodilation of smooth muscles of blood vessels leading to decrease in blood pressure. Skin Cholecalciferol is the inactive form of Vitamin D synthesized and secreted by skin in the presence of ultraviolet light of a specific wavelength. It targets hepatocytes of the liver where it is turned into calcefediol which in the kidney is changed into calcitriol, the most active, circulating form of vitamin D. Fat Leptin secreted by adipocytes of white adipose tissue to target the hypothalamus and suppresses appetite and reduces body weight. Eicosanoids and Growth Factors Eicosanoids are signaling molecules found in all body cells except red blood cells. Prostaglandins - wide variety of functions some of which are involved in enhancing inflammation, fever and pain. Thromboxane - is a modified prostaglandins that triggers vasoconstriction and stimulate platelet activation. Growth Factors Large variety of growth factors which cause cell division and stimulate tissue development, growth and repair.

GONADS

The gonads are the body organs that produce gametes; testes produce spermatocytes in males and ovaries produce oocytes in females. The gonads also synthesize and secrete sex hormones. Hormone produced by the gonads function in the following ways: Hormones regulate the menstrual cycle and stimulate oocyte production in females. Maintains pregnancy in females Promotes puberty and development of secondary sex characteristics in males and females such as growth of pubic and armpit hair. In addition, increased activity of sweat glands usually also accompanies the appearance of secondary sex characteristics. Gross Anatomy of the Testes The testes are the primary sex organ in males and are oval in shape and are suspended outside the body in the scrotum. The testes must be outside the body as the normal body temperature inhibits production of sperm. A tube-like structure called the epididymis arises from the superior portion of each testis and descends to the inferior portion of the testis where it forms the ductus deferens and ascends into the body. Microanatomy of the Testis Inside the testis, the seminiferous tubules contain three types of cells important for sperm production: Leydig cells: also known as Interstitial cells that reside within the interstitial fluid between the seminiferous tubules. Sertoli cells: also called sustentacular cells and are located in close approximation of developing sperm. They provide a structural support, produce a barrier protecting sperm from harmful blood carried substances, secrete nutrients for developing sperm and for transport through seminiferous tubules and also secrete inhibin and activin, hormones that regulate FSH secretion. Germ cells or spermatogonia - are undifferentiated cells that grow into sperm through proliferation and differentiation which describes the process know as spermatogenesis. Hormones of the Testis The primary hormone secreted by the testis was testosterone and is secreted by the Leydig cells. The principle actions are the following: development of secondary sex characteristics (deepening of voice, growth of facial hair and muscle development stimulates and maintains male reproductive organs and secretory glands and stimulates sperm production has metabolic effects, stimulates protein synthesis and muscle growth and can promote aggressive behavior Control points for testosterone secretion start in the hypothalamus which secretes Gonadotropin-releasing hormone which then stimulates Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) by the anterior pituitary gland. LH promotes testosterone secretion by Leydig cells and FSH stimulates control of sperm development (spermatogenesis). Inhibin is a hormone secreted by the Sertoli cells when sperm count is high and by negatice feedback, inhibits FSH release from the anterior pituitary gland and inhibits Gonadatropin-releasing hormone from the hypothalamus. Activin is a hormone that is the functional antagonist of inhibin and stimulates FSH release from the anterior pituitary gland. Gross Anatomy of the Ovaries The ovary is the primary female organ of the reproductive system and there are two located in the ovarian fossa close to the pelvic wall. The uterine tube (oviduct) covers the medial surface and has finger-like projections called fimbrae covering the lateral surface. It id the function of the fimbrae to direct the oocyte into the uterine tube or oviduct once it is released (ovulated) from the ovary. Microanatomy of the Ovaries Each ovary has an inner medulla region and an outer cortex. The inner medulla has many blood vessel in it and provides structural support and a rich blood supply for hormone and nutrient transport. The cortex comprises most of the volume in the ovary and contains the ovarian follicles which contain several layers of cells depending on the stage of development. Ovarian follicle cells are listed below; Granulosa cells: in the earliest follicle called the primordial follicle which is an immature ovarian follicle, there is a single layer of follicular cells. These cells surround the primary oocyte (immature egg) and these cells undergo division to form many layers called the granulomas cells as the egg matures toward ovulation. Granulosa cells secrete estrogens and inhibin. Thecal cells: cells surrounding the follicle are called the thecal cells and secrete estrogens. Corpus luteum - a corpus luteum forms from the ovarian follicle after the secondary oocyte is ovulated. The corpus luteum becomes a temporary endocrine gland secreting estrogens, progesterone, relaxin and inhibin. Hormones of the Ovaries Main female sex hormones are estrogens and progestins (primarily progesterone), both are types of steroid hormones Estrogens and progesterone: the follicle cells synthesize estrogen and the corpus luteum secrete both estrogen and progesterone. Estrogens stimulate growth of uterus lining during ovulation and menstruation and stimulate development of secondary sex characteristics during puberty such as development of mammary glands, broadening of pelvis and maturation of female reproductive organs. Relaxin: peptide hormone secreted by the corpus luteum of the ovary. Increase during the first 14 days of pregnancy, then decreases if fertilization does not occur. If pregnancy occurs, relaxin is produced by the placenta and increases the flexibility of the pubic symphysis and promotes dilation of the uterine cervix during labor. Hormones active in the female follow: Luteinizing hormone: released by anterior pituitary gland and promotes follicle growth and maturation. Ovulation is caused by an increase in Luteinizing hormone. Follicle-stimulating hormone: released by the anterior pituitary gland, promotes follicle growth and maturation and stimulates follicle cells to secrete estrogen. Gonadotropin-releasing hormone: released by hypothalamus and stimulates LH and FSH secretion from anterior pituitary gland. Estrogens inhibit Gonadotropin-releasing hormone during childhood. Activin: is the functional antagonist of inhibin and stimulates FSH release from the anterior pituitary which promotes follicular development. Human Ovarian Changes The Primary Oocyte is surrounded by a layer of granulosa cells and together form a follicle. As Primary Oocyte matures into a Secondary Oocyte, a fluid filled cavity forms and the entire structure is now called a Graafian Follicle. There is an increase of LH (luteinizing hormone) in mid-cycle which causes the secondary oocyte to ovulate and be taken up by fallopian tubes. Menstrual Cycle Events: Note the following facts and then follow the steps indicating how the pituitary and ovary exchange hormonal signals to cause the changes observed for the menstrual cycle : The pituitary is the source of both FSH (follicle stimulating hormone) and LH (luteinizing hormone). The ovary is the source of estrogen and progesterone. During the follicular phase of the menstrual cycle, the pituitary begins to secrete FSH which stimulates the growth of the follicle (egg and other follicle cells). As the follicles grow in the ovary, they produce estrogen which increases in the blood stream and inhibits the secretion of FSH in the pituitary and stimulates the production of LH to cause ovulation to occur. Once LH causes ovulation, the cells of the follicle (corpus luteum) which remain in the ovary begin to secrete progesterone which inhibits the secretion of LH by the pituitary. If fertilization of the egg occurs and implants in the endometrium, the developing embryo and placental cells maintain the corpus luteum which continues to secrete progesterone which inhibits both FSH and LH production by the pituitary during pregnancy causing no more eggs to ovulate. If no fertilization occurs, the corpus luteum degenerates and the progesterone blood levels decrease allowing FSH to begin to be secreted by the pituitary again to start the next menstrual cycle. FSH production by pituitary stimulates follicle growth in the ovary. Follicle growth produces estrogens which inhibit FSH production by the pituitary and stimulates LH production. LH stimulates ovulation and production of progesterone by ovary (corpus luteum) which inhibits LH production. Both estrogen and progesterone secretion stimulate the build-up of endometrial wall in anticipation of receiving a fertilized egg. Why do birth control pills work? Birth control pills are composed of estrogens and progesterone. Estrogens inhibit egg maturation by inhibiting FSH secretion by the pituitary gland. Ovulation doesn't occur because progesterone inhibits pituitary LH secretion without affecting endometrial build-up and the ability to menstruate. >Menstrual Cycle Problems Endometriosis: occurs when endometrial cells begin to grow in the pelvic cavity and undergo menstrual cycle. This can be very painful and if cells cover the ovary, it can make a woman infertile. Premenstrual syndrome (PMS): may develop after ovulation and result in mood swings, fluid retention, anxiety, backache and joint pains and other symptoms. Sometimes, dietary changes, regular exercise and diuretics can help alleviate pain. ·Amenorrhea: lack of a menstrual period, normal during pregnancy and in postmenopausal women and in girls who have not reached puberty. Female atheletes sometimes develop amenorrhea due to stress from strenuous exercise routine. For nonpregnant woman, lack of menstrual period can indicate a problem in the endocrine system. Dysmenorrhea (painful menstruation): associated with cramping of uterine muscles during menstruation. This can occur due to excess production of prostaglandins by the uterus producing excess smooth muscle contraction.

MUSCLES OF THE FOOt

The muscles of the foot assist the flexors and extensors of the leg to move the toes and can be divided into dorsal and plantar groups.

which muscle below is not one of the rotator cuff muscle in the shoulder region?

deltoid

When the internal intercostals and the innermost intercostals contract, what happens to the air pressure inside the thoracic cavity?

increases

which bone below is a single bone and forms the bridge of the nose?

nasal

Nucleic acids

o Nucleic acids - Nucleic acids are large molecules composed of smaller units called nucleotides. A nucleotide is composed of three parts: a pentose (five carbon) sugar, a linking phosphate group, and a nitrogenous base. Nucleic acids function in determining the characteristics of cells by controlling which proteins they produce. o Structure of nucleic acids - There are two classes of nucleic acid: DNA and RNA. Both play an important role in carrying the information required for the synthesis of proteins: a process necessary for the myriad of metabolic reactions to take place within the body. o DNA - Deoxyribonucleic acid (DNA) forms the basis of the genome. It contains the genetic code used to determine the function and development of an organism, including the traits that are inherited. DNA is composed of a long sequence of nucleotides of four different types. These nucleotides are linked together by condensation reactions between the phosphate group of one nucleotide and the pentose sugar molecule of the next. o Nucleotides: - Nucleotides are considered to be the structural unit of a nucleic acid. In DNA, each nucleotide contains one of the four possible nitrogenous bases adenine, guanine, thymine, or cytosine. However, all nucleotides contain a pentose sugar and phosphate group. o Nitrogenous bases - There are four nitrogenous bases found in DNA, which can be divided into two types based on structure: the purines and pyrimidines. - Purines: - The bases adenine and guanine are purines. They consist of a double-ring structure containing carbon, hydrogen, oxygen, and nitrogen. - Pyrimidines: - The bases thymine and cytosine are pyrimidines. They have a single ring of carbon, hydrogen, oxygen, and nitrogen. o Polynucleotides - Polynucleotides are created when two or more nucleotides join to one another via phosphodiester links. This occurs when the phosphate group of one nucleotide joins to the sugar of a neighboring nucleotide. The four different combinations of nucleotides may occur in any sequence in the polynucleotide chain. This specific DNA contains the genetic information, and allows cells to create the different kinds of proteins required by the body in order for it to function. o DNA (gross structure) - The gross structure of DNA consists of two long strands of polynucleotides coiled into alpha helices, known as a double helix. The backbone of a DNA strand is formed from alternating phosphate groups and pentose sugars, with the nitrogenous bases forming the core of the structure. The two polynucleotides are held together by hydrogen bonds between the matching bases of each strand. The bonding of these nitrogenous bases is very specific, such that a purine base always pairs with a pyrimidine base. More specifically, adenine pairs up with thymineforming two hydrogen bonds, and cytosine pairs up with guanineforming three hydrogen bonds. These base pairs are called complementary bases. This strict pairing rule means that the sequence of base pairs on one strand will predict the outcome of the second, or complementary strand. Any change to the sequence of a DNA strand is known as a mutation. For more information on the function and synthesis of DNA, see 'Cell Biology: DNA Replication and Protein Synthesis'. o RNA - Ribonucleic acid (RNA) is also a type of nucleic acid. The structure of RNA is extremely similar to that of DNA; however, there are a few key differences: o Key differences between DNA and RNA - RNA is single stranded. - RNA uses the pyrimidine base uracilinstead of thymine. - RNA nucleotides use ribose as opposed to deoxyribose. - There are several different types of RNA: messenger RNA, transfer RNA, and ribosomal RNA; but they all have one thing in common: they facilitate the synthesis of proteins from DNA. For more information on the function and synthesis of RNA, see 'Cell Biology: DNA Replication and Protein Synthesis'. o Functions of nucleic acids - DNA replication: - The primary function of DNA and RNA is to mediate the information transfer, storage, and expression of genetic information during protein synthesis and DNA replication, both of which are vital processes in the body. Expression and reading of genetic information is the basis of life, as all functions and processes in the body are coded by the genes found in DNA. - Protein synthesis - DNA serves as a template, directing protein synthesis within the cell. Sections of DNA responsible for producing proteins are known as genes, and the sequence of nitrogenous bases are referred to as the genetic code. This genetic code determines the structure and function of proteins produced.For more information on the function of DNA in protein synthesis, see 'Cell Biology: DNA Replication and Protein Synthesis'.

This butterfly-shaped bone is located at the base of the cranium and contains the pituitary fossa.

sphenoid

what is the origin of the subscapularis muscle in the shoulder?

subscapular fossa of scapula

The erector spinae muscles consist of which set of three muscles listed below? 1. semispinalis, quadratus, longissimus 2. quadratus, semispinalis, iliocostalis 3. spinalis, semispinalis, iliocostalis 4. longissimus, spinalis, iliocostalis

4. longissimus, spinalis, iliocostalis

which bone listed below contains the site for teeth attachment, forms most of the hard palate and contains the largest sinuses in our skull? 1. palatine 2. nasal 3. mandible 4. maxilla 5. lacrimal 6. hyoid 7. zygomatic

4. maxilla

what anatomic feature of the humerus is known as the "funny bone"? 1. deltoid tuberosity 2. lateral epicondyle 3. lesser tubercle 4. medial epicondyle 5. greater tubercle

4. medial epicondyle

What is the origin of the orbicularis oris muscle? 1. superior tarsus (eyelid) 2. lesser wing os sphenoid 3. temporal bone 4. modiolus 5. zygomatic bone

4. modiolus

Which of the muscles below insert on the lesser trochanter of the femur? 1. gluteus medius 2. gluteus minimus 3. gluteus maximus 4. none of these muscles

4. none of these muscles

What is the origin for the occipital belly of the occipitofrontalis muscle? 1. skin of forehead 2. temporal bone 3. Galea aponeurotica 4. occipital bone 5. frontal lobe

4. occipital bone

In intramembranous ossification during the formation of an ossification center, the mesenchyme cells differentiate initially into which one of the following bone cells? 1. osteoblasts 2. osteoclasts 3. osteocytes 4. osteogenic cells

4. osteogenic cells

A straight muscle fits into which one of the following categories? 1. convergent 2. fusiform 3. pennate 4. parallel 5. orbicular

4. parallel

The superior radioulnar joint is an example of which one of the following types of joint? 1. ball-and-socker 2. saddle 3. gliding (plane) 4. pivot 5. condyloid (ellipsoid)

4. pivot

which carpal bone can be palpated in the region known as the anatomic snuff box? 1. lunate 2. capitate 3. triquetral 4. scaphoid 5. trapezium

4. scaphoid

What is the origin for the internal intercostals? 1. superior borders of ribs 1 - 11 2. inferior borders of ribs and costal cartilages 1 - 11 3. inferior borders of ribs 1 - 11 4. superior borders of ribs 2 - 12 5. internal aspect of ribs 1 - 11

4. superior borders of ribs 2 - 12

Which terms below best describe the joints that permit free movements? 1. fibrous and synarthroses 2. fibrous and diarthroses 3. cartilaginous and amphiarthroses 4. synovial and diarthroses 5. synovial and synarthroses

4. synovial and diarthroses

What is the function of the superior articulating facet of a vertebra? 1. to articulate with the inferior facet of the vertebra below it 2. to articulate with the inferior facet of the vertebra above it 3. to articulate with the superior facet of the vertebra above it 4. to articulate with the ribs

2. to articulate with the inferior facet of the vertebra above it

Free nerve endings

- A bare dendrite, lacking structural specialization, is called a free nerve ending. They are associated with a variety of cutaneous sensations. - Found throughout the skin, they terminate in the stratum granulosum of the epithelium.

Hair matrix

- A germinal layer of cells, called the hair matrix, surrounds the papilla of the hair and gives rise to all cells within a hair, including the internal root sheath.

Cuticle

- A single layer of thin, flat cells that are heavily keratinized. Each cell partially overlaps the cuticle cell superficial to it, with the exposed edge pointing upwards. - In the root and bulb, the medulla, cortex, and cuticle are surrounded by additional layers which make up the hair follicle. The hair follicle is composed of an epithelial root sheath, and a dermal root sheath.

What muscle forms the innermost layer of the sidewalls of the abdomen? 1. external oblique 2. transverse abdominis 3. rectus abdominis 4. internal oblique

2. transverse abdominis

Of the three cranial fossae, which one is a depression formed by the sphenoid and temporal bones? 1. middle cranial fossa 2. anterior cranial fossa 3. posterior cranial fossa

1. middle cranial fossa

What is the insertion of the buccinator muscle? 1. modiolus 2. zygomatic bone 3. lesser wing of sphenoid 4. temporal bone 5. superior tarsus (eyelid)

1. modiolus

Yellow bone marrow is principally responsible for storing which one of the following substances? 1. glucose 2. triglycerides 3. glycerol 4. proteins

2. triglycerides

the fibula is not a weight bearing bone and if broken, you can still walk on your leg but it will be painful. 1. true 2. false

2. true

Ribs 1-7 attach anteriorly to the sternum are called what type of ribs? 1. floating ribs 2. true ribs 3. false ribs

2. true ribs

when you move your head up and down as in nodding yes to a question, what best describes the action of the atlas vertebra? 1. the atlas articulates with the axis 2. the atlas does not articulate with any bone 3. the atlas articulates with the superior articulating facet of the axis 4. the atlas articulates with the occipital condyles of the occipital bone

4. the atlas articulates with the occipital condyles of the occipital bone

Which artery is responsible for bringing nutrients and oxygen to the inner part of compact bone, spongy bone and bone marrow? 1. nutrient artery 2. epiphyseal artery 3. metaphysical artery

1. nutrient artery

What is the insertion of the gluteus maximus? 1. greater trochanter of femur 2. lesser trochanter of femur 3. gluteal tuberosity 4. acetabulum 5. tibial tuberosity

3. gluteal tuberosity

If the left sternocleidomastoid muscle contracts and the right does not, what action results? 1. head moves to right 2. head moves down toward the ground 3. head moves to left 4. head move up toward the ceiling

3. head moves to left

Which one of the following arteries is responsible for providing arterial blood to both the diaphysis and metaphysis of a long bone? 1. nutrient artery 2. metaphysical artery 3. periosteal artery 4. epiphyseal artery 5. nutrient vein

1. nutrient artery

What is the name of the large muscle on the anterior chest wall that inserts on the humerus and can adduct and internally rotate the humerus? 1. pectoralis major 2. latissimus dorsi 3. brachialis 4. biceps brachii 5. triceps brachii

1. pectoralis major

Which two of the following muscles insert onto the humerus? 1. pectoralis major, latissimus dorsi 2. rhomboid major, pectoralis minor 3. serratus anterior. pectoralis mior 4. rhomboid major, serratus anterior

1. pectoralis major, latissimus dorsi

Which part of the temporal bone contains the internal acoustic meatus and the inner ear. 1. petrous part 2. squamous oart 3. tympanic part 4. mastoid process

1. petrous part

When you "stubb" your toe, what bony type are you bumping and hurting? 1. phalanges 2. metacarpals 3. carpal bones

1. phalanges

In the final stage of endochondral ossification, the epiphyseal plate is formed from which one of the following types of cartilage? 1. elastic cartilage 2. fibrocartilage 3. hyaline cartilage

3. hyaline cartilage

The bones of synchondroses are connected by a layer of which one of the following types of cartilage? 1. elastic cartilage 2. fibrocartilage 3. hyaline cartilage

3. hyaline cartilage

In movements possible around a synovial joint, __________ describes the movement in which two bones are widened to an angle greater than the normal amount. 1. abduction 2. flexion 3. hyperextension 4. extension 5. adduction 6. circumduction

3. hyperextension

Which bone below contains the nasolacrimal duct and forms the anterior part of the medial wall of the orbit. 1. palatine 2. nasal 3. lacrimal 4. zygomatic 5. maxilla 6. hyoid 7. mandible

3. lacrimal

At the femur's most distal end, what bump can you palpate on the lateral surface of the femur at the knee joint? 1. greater trochanter 2. lesser trochanter 3. lateral condyle 4. medial condyle 5. lateral epicondyle

3. lateral condyle

Which muscle of the shoulder and shoulder girdle has an origin of T1 - T12 spinous processes, iliac crest and ribs 9 - 12 and inserts on the humerus with an action of extending, adducting and medially rotating the arm at the shoulder joint? 1. triceps brachii 2. brachialis 3. latissimus dorsi 4. biceps brachii 5. pectoralis major

3. latissimus dorsi

Which part of the sternum is most superior portion and site of articulation with the first and second costal cartilages? 1. diploid process 2. body 3. manubrium

3. manubrium

Which two of the following are contractile proteins present in skeletal muscle? 1. myosin and troponin 2. actin and titin 3. myosin and actin 4. myosin and actin 5. troponin and actin

3. myosin and actin

What portion of the hip do we sit on and is the site for muscle attachment? 1. acetabulum 2. iliac crest 3. obturator foramen 4. ischial tuberosity 5. anterior superior iliac crest

3. obturator foramen 4. ischial tuberosity

An immature bone cell found in growing bone is called what? 1. lacunae 2. osteocyte 3. osteoblast 4. osteoclast 5. osteon

3. osteoblast

Which of the muscles listed below is located on the anterior chest wall, inserts on the scapula and has an action of pulling the shoulder girdle forwards and downwards? 1. triceps brachii 2. trapezius 3. pectoralis minor 4. serrates anterior 5. biceps brachii

3. pectoralis minor

Which leg muscle below acts on the knee joint with origin on the lateral condyle of femur, insertion on the tibia and action of rotating femur laterally? 1. flexor halluncis longus 2. flexor digitorum longus 3. popliteus 4. soleus 5. gastrocnemius

3. popliteus

what feature is only found on cervical vertebra? 1. presence of articulation facets 2. presence of a vertebral body 3. presence of transverse foramen 4. presence of vertebral spine

3. presence of transverse foramen

From the list below, choose the correct term for a muscle that is primarily responsible for instigating a particular movement, such as the role of the triceps brachii in extending the elbow? 1. synergist 2. protagonist 3. prime mover 4. fixator 5. antagonist

3. prime mover

Which movement about a synovial joint describes the movement of the scapula forward? 1. pronation 2. adduction 3. protraction 4. retraction 5. abduction 6. supination

3. protraction

Choose the action of the zygomaticus minor muscle. 1. closing and pursing the lips 2. keeps food from collecting between teeth and cheeks 3. raises the upper lip as in smiling 4. raises the upper eyelid 5. closes eye as in winking

3. raises the upper lip as in smiling

Which of the following muscles does not insert on the tibial tuberosity via the patellar tendon? 1. vastus lateralis 2. vastus medialis 3. sartorius 4. rectus femoris 5. vastus intermedius

3. sartorius

The acromial end of the clavicle articulates with which one of the following bones? 1. sternum 2. 1st rib 3. scapula 4. humerus

3. scapula

When describing a muscle, which one of the following words best describes the Latin word "brevis"? 1. huge 2. largest 3. short 4. smallest 5. long

3. short

Which one of the following joints allows the widest range of movement in the body? 1. knee 2. elbow 3. shoulder 4. temporomandibular 5. hip

3. shoulder

Which one of the following muscle groups acts to increase the size of the throrax by drawing the ribs upwards and outwards? 1. diaphragm 2. innermost intercostals 3. transversus abdominis 4. internal intercostals 5. external intercostals

5. external intercostals

Which thin muscle of the posterior forearm divides into four thin tendons distally with an origin on the ulna, insertion on phalanges 2 - 5 and an action to flex the wrist and fingers 2 - 5? 1. brachioradialis 2. flexor pollicis longus 3. pronator teres 4. flexor digitorum superficialis 5. flexor digitorum profundus

5. flexor digitorum profundus

Which muscle below forms the bulk of the calf musculature, originates on the medial and lateral condyle of the femur and inserts on the calcaneus. 1. flexor digitorum longus 2. soleus 3. flexor halluncis longus 4. popliteus 5. gastrocnemius

5. gastrocnemius

Synovial fluid in a synovial joint is composed primarily of what? 1. saline 2. plasma 3. glycolipids 4. interstitial fluid 5. hyaluronic acid

5. hyaluronic acid

What is the origin of the teres major muscle in the shoulder? 1. infraspinous fossa of scapula 2. clavicle 3. supraspinous fossa of scapula 4. subscapular fossa of scapula 5. inferior angle of scapula 6. lateral border of scapula

5. inferior angle of scapula

which bone below contains the coronoid process at its posterior for the site of attachment of the temporals muscle on either side of the head? 1. hyoid 2. lacrimal 3. maxilla 4. nasal 5. mandible 6. zygomatic 7. palatine

5. mandible

Which one of the following terms is used for the thread-like organelles composed of actin and mysosin filaments found in muscles cells? 1. tropomysium 2. transverse tubules 3. muscle fascicles 4. muscle fiber 5. myofibrils

5. myofibrils

identify the large foramen formed by the pubis and the ischium in the hip? 1. acetabulum 2. ischial tuberosity 3. iliac crest 4. anterior superior iliac crest 5. obturator foramen

5. obturator foramen

This bone forms the back and base of the skull and contains the foramen magnum. 1. sphenoid 2. temporal (tympanic part) 3. ethmoid 4. frontal 5. occipital

5. occipital

What is the name of the muscle that surrounds the eye and is used to close the eye tightly to keep out a foreign object? 1. orbicularis fris 2. levator palpebrae superioris 3. buccinators 4. zygomatic minor 5. orbicularis oculi

5. orbicularis oculi

Which small square muscle below lies on the anterior distal forearm with its origin on the ulna, insertion on the radius and action to pronate the forearm. 1. pronator quadratus 2. extensor digitorum 3. anconeus 4. flexor pollicis longus 5. brachioradialis

1. pronator quadratus

Which of the quadriceps muscles below is the most anterior and originates on the anterior superior iliac spine and acetabulum of the hip bone. 1. rectus femoris 2. vastus lateralis 3. vastus intermedius 4. sartorius 5. vastus medialis

1. rectus femoris

Which one of the following carpal bones is located in the proximal row and lies lateral to the lunate bone? 1. scaphoid 2. capitate 3. pisiform 4. hamate 5. triquetrum

1. scaphoid

Choose the correct class of lever to describe when the load is placed between the fulcrum and the effort (force) as in raising your heel from the ground 1. second class lever 2. third class lever 3. fourth class level 4. first class lever

1. second class lever

In addition to the gastrocnemius, what other leg muscle forms the Achilles tendon? 1. soleus 2. flexor digitorum longus 3. flexor halluncis longus 4. popliteus

1. soleus

What muscle has an origin on both the clavicle and sternum and an insertion on the mastoid process of the temporal bone? 1. sternocleidomastoid muscle 2. temporalis 3. masseter 4. semispinalis capitis

1. sternocleidomastoid muscle

What is the origin of the supraspinatus muscle in the shoulder? 1. supraspinous fossa of scapula 2. inferior angle of scapula 3. infraspinous fossa of scapula 4. subscapular fossa of scapula 5. lateral border of scapula 6. clavicle

1. supraspinous fossa of scapula

From a functional point of view, what type of joint provides no movement at all? 1. synarthroses 2. amphiarthroses 3. diarthroses

1. synarthroses

Which one of the following terms best describes the role of brachialis, given that it assists biceps brachii in flexing the elbow? 1. synergist 2. prime mover 3. antagonist 4. agonist 5. fixator

1. synergist

Which bone can you feel in your leg that is commonly known as the shin bone? 1. tibia 2. fibula 3. talus 4. femur 5. calcaneus

1. tibia

Identify the large muscle on the back of the arm with three heads that have an origin on the scapula and humerus and insertion on the olecranon of the ulna. 1. triceps brachii 2. latissimus dorsi 3. brachial 4. biceps brachii 5. pectoralis major

1. triceps brachii

A motor unit is a motor neuron and all the muscle cells that it innervates and causes to contract. 1. true 2. false

1. true

Acetylcholine is released from the tip of the motor neuron at the neuromuscular junction where it binds to receptors on the muscle membrane to cause the muscle fiber to contract. 1. true 2. false

1. true

All of the rotator cuff muscles insert on the greater tubercle of the humerus. 1. true 2. false

1. true

An epiphyseal plate of cartilage forms at either end of a long bone and is the future growth plate so bone may grow longer. 1. true 2. false

1. true

At the wrist joint, tendons are enclosed in sheaths which can become inflamed due to repetitive movements such as typing to produce carpal tunnel syndrome. 1. true 2. false

1. true

Hormones from the parathyroid gland are involved in releasing calcium from bone and also in storing it in bone 1. true 2. false

1. true

In later years, especially in women, osteoporosis may set in and bone loss of Calcium may occur faster thereby weakening bones of the hip and spine 1. true 2. false

1. true

In muscle contraction, when calcium is released from the cellular storage system, the myosin head forms a ""cross-bridge"" between the myosin and the actin filament. 1. true 2. false

1. true

Ligaments connect bone to bone at places called joints 1. true 2. false

1. true

Muscle tension is the collective force formed during contraction. 1. true 2. false

1. true

Skeletal muscles contract in response to nervous stimulation but if the nerves are cut, the muscle will not contract unless stimulated artificially. 1. true 2. false

1. true

Spongy bone tissue is found in the head of long bones and in the flat bones of the skull and contains red bone marrow and participates in red blood cell production. 1. true 2. false

1. true

The braincase consists of the eight bones that surround your brain 1. true 2. false

1. true

The compression of intervertebral discs as we age results in loss of height and increased risk of pinched spinal nerves. 1. true 2. false

1. true

The diaphragm separates the thorax from the abdomen. 1. true 2. false

1. true

The force with which a skeletal muscle can contract is related to the length of its sarcomeres. 1. true 2. false

1. true

The lungs and heart are protected by the ribs, sternum and vertebral column. 1. true 2. false

1. true

The origin of the triceps is the scapula. 1. true 2. false

1. true

The platysma is the antagonist of the zygomatic minor muscle. 1. true 2 false

1. true

The proximal end of ulna forms the elbow. 1. true 2. false

1. true

The sarcomere is considered to be the contractile unit of the muscle. 1. true 2. false

1. true

The tendons of the abdominal muscles merge together at the fron of the abdomen to form a fibrous sheath with a mid-portion known as the linea alba. 1. true 2. false

1. true

The tibia of the lower leg forms the "shin bone". 1. true 2. false

1. true

The zygomatic minor muscle is the antagonist of the platysma. 1. true 2. false

1. true

the cervical curve of the vertebral column forms when the baby is able to hold its head up 1. true 2. false

1. true

the pelvic girdle is larger and more basin-like in females than males for child bearing and birth 1. true 2. false

1. true

the ulna articulates with the radius by way of an interosseous membrane 1. true 2. false

1. true

Interstitial growth at the epiphyseal growth plate occurs at which one of the following zones of cartilage? 1. zone of proliferating cartilage 2. zone of resting cartilage 3. zone of calcified cartilage 4. zone of hypertrophic cartilage

1. zone of proliferating cartilage

Which one of the following best describes a motor unit? 1. a single muscle group and its innervating nerves 2. l the myofilaments in a muscle fiber 3. somatic motor neuron and all the muscle fibers it innervates 4. a single muscle fiber 5. an antagonistic pair of muscles

3. somatic motor neuron and all the muscle fibers it innervates

The oxygen debt of a muscle in prolonged state of contraction is the time it takes to replace all the creatine phosphate reserves. 1. true 2. false

2. false

The primary and secondary curves of the vertebral column are present from birth 1. true 2. false

2. false

The sarcoplasmic reticulum is a type of rough Endoplasmic Reticulum which releases Calcium ions during contraction of the muscle fiber. 1. true 2. false

2. false

The ulna primarily articulates with only the humerus and the carpal bones of the wrist 1. true 2. false

2. false

When a sarcomere contracts, the myosin filaments slide over the actin filaments bringing the myosin filaments closer together. 1. true 2. false

2. false

When blood calcium level is low, PTH (parathyroid hormone) is released and stimulates osteoblasts to dissolve bone, releasing calcium. 1. true 2. false

2. false

Yellow bone marrow is in active formation of red blood cells and some types of white blood cells. 1. true 2. false

2. false

the Pectoral Girdle is composed of the clavicle, scapula and humerus. 1. true 2. false

2. false

we have a great range of motion in our pectoral girdle because it is tightly attached to the body frame 1. true 2. false

2. false

Which muscle below becomes tendinous at back of ankle and travels to sole of foot where it divides into four tendons and can flex the four lateral toes? 1. popliteus 2. flexor digitorum longus 3. flexor halluncis longus 4. gastrocnemius 5. soleus

2. flexor digitorum longus

Which muscle below is located deep in the calf, becomes tendinous at back of ankle and travels into sole of foot to insert on the distal phalanx and has an action to flex the big toe. 1. soleus 2. flexor halluncis longus 3. popliteus 4. flexor digitorum 5. gastrocnemius

2. flexor halluncis longus

Which thin muscle of the posterior forearm and thumb has its origin on the ulna, insertion on the 1st distal phalanx and action to flex the thumb. 1. flexor digitorum superficialis 2. flexor pollicis longus 3. flexor digitorum profundus 4. pronator teres 5. brachioradialis

2. flexor pollicis longus

what structure of the femur at its most proximal end can be palpated on the side of the hip? 1. medial condyle 2. greater trochanter 3. lateral epicondyle 4. lesser trochanter 5. lateral condyle

2. greater trochanter

If both the right and left sternocleidomastoid muscles contract together, what action results? 1. head moves to right 2. head moves down toward the ground 3. head moves up toward the ceiling 4. head moves to left

2. head moves down toward the ground

Which bone is horseshoe-shaped and located just superior to the larynx? 1. nasal 2. hyoid 3. palatine 4. lacrimal 5. zygomatic 6. mandible 7. maxilla

2. hyoid

what anterior edge on the hip can be palpated and is the site of attachment for abdominal muscles? 1. obturator foramen 2. iliac crest 3. acetabulum 4. ischial tuberosity 5. anterior superior iliac crest

2. iliac crest

Which of the following muscles are flexors of the hip? 1. tensor fascia lata, psoas 2. iliacus, psoas 3. gluteus medius, iliacus 4. gluteus maximus, gluteus medius

2. iliacus, psoas

What is the origin of the infraspinatus muscle in the shoulder? 1. lateral border of scapula 2. infraspinous fossa of scapula 3. inferior angle of scapula 4. supraspinous fossa of scapula 5. clavicle 6. sub scapular fossa of scapula

2. infraspinous fossa of scapula

Choose the correct classification for muscle contraction which involves no change in length or tension. 1. concentric isotonic contraction 2. isometric contraction 3. isotonic contraction 4. eccentric isotonic contraction

2. isometric contraction

To which one of the following classes do bones that act as levers for the movement of skeletal muscle belong? 1. flat 2. long 3. irregular 4. short 5. sesamoid

2. long

what feature distinguishes thoracic vertebra from other types? 1. absence of articulating facets on transverse processes 2. presence of articulating facets on transverse processes 3. largest body of all vertebral types 4. presence of transverse foramen on transverse process

2. presence of articulating facets on transverse processes

Which muscle below is the longest muscle in the body and travels obliquely across the front of the thigh? 1. vastus medialis 2. sartorius 3. rectus femoris 4. vastus lateralis 5. vastus intermedius

2. sartorius

which carpal bones articulate with the radius and ulna? 1. pisiform, lunate and triquetral 2. scaphoid, lunate and triquetral 3. trapezium, trapezoid, capitate 4. hamate, trapezoid, capitate

2. scaphoid, lunate and triquetral

what two bones does the clavicle articulate with? 1. scapula and humerus 2. scapula and manubrium 3. humerus and manubrium

2. scapula and manubrium

Which one of the following superficial muscles of the back elevates the ribs? 1. serratus posterior inferior 2. serratus posterior superior 3. quadratus lumborum

2. serratus posterior superior

Where does the frontal belly of the occipitfrontalis muscle insert? 1. occipital bone 2. skin of forehead 3. Galea aponeurotica 4. temporal bone 5. frontal bone

2. skin of forehead

Of the listed items below, which is not an origin for the deltoid muscle? 1. spine of the scapula 2. subscapular fossa of scapula 3. clavicle 4. acromion of the scapula

2. subscapular fossa of scapula

Which one of the following types of fibrous joint occurs when two bones are bound together by an interosseous ligament? 1. suture 2. syndesmosis 3. gomphosis

2. syndesmosis

Which one of the following muscles does not insert on the hyoid bone? 1. sternohyoid 2. digastric 3. sternothyroid 4. omohyoid 5. thyrohyoid

3. sternothyroid

Which bone listed below is not part of the viscerocranium? 1. zygomatic 2. palatine 3. temporal 4. nasal 5. lacrimal

3. temporal

Which three of the muscles below have partial insertion on the linea alba? 1. rectus abdominis, transversus abdminis, external oblique 2. diaphragm, rectus abdominis, transversus abdminis 3. transversus abdominis, internal oblique, external oblique 4. ansversus abdominis, internal oblique, rectus abdominis

3. transversus abdominis, internal oblique, external oblique

Identify the large, triangular muscle on back of the neck, shoulders and upper back that can retract the scapula and extend and laterally flex the head and neck? 1. biceps brachii 2. serratus anterior 3. trapezius 4. triceps brachii 5. pectoralis minor

3. trapezius

a joint is a type of joint which has a capsule that secrete slippery synovial fluid into the joint to make movement more easy 1. cartilaginous 2. synovial 3. fibrous

2. synovial

Which tarsal bone does the fibula articulate with in the ankle region? 1. navicular 2. talus 3. cuboid 4. lateral cuneiform 5. calcaneus

2. talus

When you move your head from right to left and left to right as in signifying no when asked a question, what best describes the action of the atlas and axis? 1. the axis articulate with the occipital condyles 2. the atlas articulates with the axis 3. the atlas does not articulate with any bone 4. the atlas articulates with the occipital condyles of the occipital bone

2. the atlas articulates with the axis

Which one of the following types of contractile filaments found in the sarcoplasm of smooth muscles has a tropomyosin component? 1. intermediate filaments 2. thin filaments 3. thick filaments

2. thin filaments

Which part of the temporal bone contains the external acoustic meatus and the styloid process projecting downward for attachment of ligaments and muscles? 1. mastoid process 2. petrous part 3. tympanic part 4. squamous part

3. tympanic part

What is the action for the platysma muscle? 1. raises the upper eyelid 2. closing and pursing the lips 3. wrinkles the skin of the neck 4. raises the upper lip as in smiling 5. closes eye as in winking

3. wrinkles the skin of the neck

Choose the bone listed below that is not part of the neurocranium? 1. sphenoid 2. frontal 3. zygomatic 4. ethmoid 5. occipital

3. zygomatic

What is the origin of the masseter muscle? 1. temporal bone 2. maxilla bone 3. zygomatic bone 4. mandible (coronoid process) 5. nasal bone

3. zygomatic bone

Which thin muscle crosses the front of the elbow with an origin on the humerus and coronoid process of ulna, insertion on radius and action to flex elbow and pronate forearm? 1. flexor pollicis longus 2. flexor digitorum superficialis 3. brachioradialis 4. flexor digitorum profundus 5. pronator teres

5. pronator teres

What is the origin of the rectus abdominis muscle in the trunk musculature? 1. manubrium of sternum 2. ribs 5 - 12 3. costal cartilages 9 - 12 4. xiphoid process of sternum and costal cartilages 5. pubis of hip bone

5. pubis of hip bone

Which of the muscles listed below is located between the ribs and scapula and functions to protract the scapula and pectoral girdle? 1. trapezius 2. triceps brachii 3. pectoralis minor 4. biceps brachii 5. serrates anterior

5. serrates anterior

When you kneel on your knee, what structure on the tibia are you kneeling on? 1. medial malleolus 2. anterior border 3. medial condyle 4. lateral condyle 5. tibial tuberosity

5. tibial tuberosity

Which of the following best describes cardiomyocytes? 1. tire easily, branched 2. tire easily, lack nuclei 3. lack nuclei, branched, linked by intercalated discs 4. branched, linked by intercalated discs, striated

4. branched, linked by intercalated discs, striated

In movements possible around a synovial joint, __________ describes the movement of an arm in as wide a circle as possible 1. abduction 2. adduction 3. hyperextension 4. circumduction 5. flexion 6. extension

4. circumduction

The medullary cavity is a feature of which one of the following regions of a long bone? 1. periosteum 2. epiphysis 3. metaphysis 4. diaphysis

4. diaphysis

The muscles of the back can be divided into which three of the following categories? 1. multifidus, erector spinae, superficial muscles 2. multifidus, iliocostalis cervicis, transversospinalis 3. erector spinae, iliocostalis cervicis, multifidus 4. erector spinae, transversospinalis, superficial muscles

4. erector spinae, transversospinalis, superficial muscles

Single unit smooth muscle is found in which one of the following? 1. male reproductive system 2. iris muscles 3. airways of the lungs 4. arrestor pili muscles 5. walls of blood vessels

5. walls of blood vessels

Which of the following structures pass through openings in the diaphragm? 1. heart, esophagus, aorta 2. liver, esophagus, aorta 3. esophagus, aorta, superior vena cava 4. esophagus, aorta, inferior vena cava 5. superior vena cava, heart, liver

4. esophagus, aorta, inferior vena cava

Which one of the following terms best describes a muscle that holds the proximal end of another muscle in place? 1. antagonist 2. agonist 3. synergist 4. fixator 5. prime mover

4. fixator

What is the insertion of the gluteus medius? 1. lesser trochanter of femur 2. tibial tuberosity 3. acetabulum 4. greater trochanter of femur 5. gluteal tuberosity

4. greater trochanter of femur

Which suture is responsible for holding together the occipital and parietal bones of the cranium? 1. sagittal suture 2. coronal suture 3. pterion 4. lambdoid suture 5. asterion

4. lambdoid suture

What is the origin of the teres minor muscle in the shoulder? 1. inferior angle of scapula 2. clavicle 3. infraspinous fossa of scapula 4. lateral border of scapula 5. subscapular fossa of scapula 6. supraspinous fossa of scapula

4. lateral border of scapula

What is the origin of the levator palpebrae superioris muscle? 1. superior tarsus (eyelid) 2. zygomatic bone 3. modiolus 4. lesser wing of sphenoid 5. temporal bone

4. lesser wing of sphenoid

What muscle has an action of raising the upper eyelid? 1. orbicularis oris 2. zygomatic minor 3. buccinators 4. levator palpebrae superioris 5. orbicularis oculi

4. levator palpebrae superioris

Which one of the following names is given to the longitudinal ridge on the posterior aspect of the femoral shaft that provides an origin point for a number of muscles, including the biceps femoris, adductor magnus and vastus lateralis? 1. greater trochanter 2. intertrochanteric crest 3. intercondylar fossa 4. linea aspera

4. linea aspera

Acids, bases, and salts

- Acids are substances that release hydrogen ions when dissolved in water. - Bases when dissolved in water combine with hydrogen ions to make HYDROXYL IONS available (OH ions). Acids combined with bases can neutralize each other. Example = Acid-Base Reaction

Regulating gene action

- All cells have the same sets of genes but only some genes are turned on or respond to external factors in different cells. - Some genes are controlled by "regulatory proteins" which when present may turn on or off certain genes. - Hormones may also turn on certain genes such as prolactin activates genes in mammary gland cells that synthesize milk. Other cells such as liver or heart cells also have the same genes but lack the receptors to bind prolactin and do not produce milk.

Introduction chemistry Dr. K

- An element is a fundamental form of matter that occupies space and cannot be broken down into something else. - There are 92 natural elements such as hydrogen, sodium, oxygen, lithium, argon, sulfur, etc. - The Human body is composed of many elements, a body's worth has increased greatly over the years from a few dollars to many thousands of dollars due to value of isolated enzymes, hormones and now even our genes are worth millions if they can be isolated and placed inside other organisms so their products can be produced and isolated. - An Element has a nucleus formed of protons and neutrons (exception is hydrogen, has only one proton). - Stable elements have equal number of protons and neutrons, example - carbon 12 has 6 protons and 6 neutrons or an atomic number of 6 (protons) and an atomic mass of 12 (protons and neutrons) - Unstable or radioactive elements such as carbon 14 have more neutrons (two more) than protons and exhibits a half-life of 5715 years and is used in dating wood and archeological specimans. Iodine 131 is radioactive with a half-life of eight days and is used to treat thyroid gland disorders. Half-life example. - The number of electrons in the outer orbit determine degree of reactivity of an element, example = sodium electron shells . The most unreactive of elements are those that have their outer electron shell completely filled such as argon.

Anatomical language

- Anatomical language refers to the standard set of terms used to describe the location of structures in the body in relation to their surroundings. when describing anatomical features, a standardized language is used for body positions and regional names - Anatomical position: - In order to avoid confusion when describing the body, it is always described in the anatomical position - In the anatomical position, a person stands erect, legs together and arms by the sides of the body, with the head, eyes, toes, and palms of the hands facing forward. It is important to remember that the palms face forward as their relaxed position is generally facing inwards. - The anatomical position allows us to describe the position of structures in relation to their surroundings, e.g., 'the hear lies above the diaphragm'. It also avoids confusion as to whether the body is lying down or standing up - You should also bear in mind that when looking at a person in the anatomic position, their right side is on your left. The structures will always be described as they are to the subject rather than as they appear to you - Anatomical areas: - The body is split up into two main areas, the axial and appendicular regions. The axial region refers to the head, vertebral column and trunk, and the appendicular region refers to the upper limb, and the lower limb. Each area is further divided into descriptive regions: o Axial areas: - Abdominal: abdomen - Cephalic: head - Cervical: Neck - Cranial: skull - Facial: face - Inguinal: groin - Interscapular: between the two scapulae - Lumbar: lower back - Nuchal region: Posterior neck - Pectoral: chest - Perineal: Perineum - Pubic: mons pubis (pubic bone) - Sacral: sacrum - Sternal: sternum - Thoracic: chest - Umbilical: navel (belly button) - Vertebral: spinal column o Appendicular areas - Upper limb: · Acromial: Acromion of the shoulder · Antebrachial: forearm · Axillary: armpit · Brachial: arm · Carpal: wrist · Cubital: elbow · Dorsum of hand: Back of the hand · Palmar: palm of the hand · Scapular: Scapula - Lower limb: · Calcaneal: heel · Coxal: hip · Crural: leg · Dorsum of foot: top of the foot · Femoral: thigh · Gluteal: buttocks · Patellar: front of the knee · Plantar: sole of the foot · Popliteal: Back of the knee · Tarsal: ankle

Mutations and protein synthesis:

- Case of Sickle Cell Anemia - Sickle cell hemoglobin differs from normal hemoglobin by only a single amino acid. The amino acid valine is substituted for the amino acid glutamic acid. - Valine codon = GUA - Glutamic acid codon = GAA - By changing just one base in the glutamic acid codon (middle base = A) to U, valine is inserted into the developing hemoglobin molecule. - Glutamic acid = hydrophilic amino acid - Valine = hydrophobic amino acid - Hydrophilic groups like to be near the surface of the protein to be near water molecules but hydrophobic groups like to be near the interior of the protein. Thus, changing one hydrophilic amino acid for one hydrophobic amino acid can have a dramatic effect on protein structure. - This type of genetic mutation is called a "base pair substitution" and is considered to be an example of a "point mutation". - Classes of substances that can cause mutations in cells are termed "mutagens". Some known mutagens are UV light, ionizing radiation, tobacco smoke ingredients and free radicals.

Stains

- Cells are almost colorless and therefore require staining for microscopic analysis. A variety of generic stains exist for the visualization of various cellular components. In addition, immunohistochemical techniques permit the visualization and localization of particular molecular targets. - General staining of cellular material Staining methods are routinely used to give a general color to all cellular material for visualization under a microscope. Below are some examples of commonly used stains: - Methyl blue: Methyl blue is widely used in differential staining of tissue sections, where more than one chemical stain is used, such as trichrome staining. - It stains collagen blue. - Hematoxylin and eosin (H&E): H&E staining is used to differentiate nucleic acids in the nucleus from basic proteins within the cytoplasm. - Cell nuclei stain purple/black (hematoxylin) and most components of the cell cytoplasm stain pink/red (eosin). - van Gieson: The van Gieson stain is used for general staining of connective tissue fibers. - Collagen fibers stain pinkish-red, muscle stains yellow, and elastic fibers stain brown-black. - Trichrome: Trichrome staining uses three different dyes to differentially stain cellular components. One of these is often methyl blue (methyl blue is rarely used on its own). There are multiple methods of trichrome staining, each of which will highlight a different aspect of the tissue. - The colors depend on the specific dyes being used. For example, a common trichrome stain can be used to differentiate between muscle fibers (stained red) and collagen fibers (stained blue or green). - silver nitrate: Silver nitrate solution can be used to stain tissues in several different ways. One method, called Golgi's method, selectively stains the entirety of some neurons black, thus revealing their cellular architecture. A different technique can be used to highlight reticular fibers. - Immunohistochemical methodsImmunohistochemistry utilizes a different approach to visualize cellular contents: rather than dyes, it exploits the highly specific interaction between antibody and antigen to allow precise identification, localization, and in some cases, quantification, of cellular proteins, such as receptors or enzymes.

Basic aspects of cell structure and function

- Cells vary in shape and size, and whether or not they even possess a nucleus. - Prokaryotic cells - cells with no nucleus and the DNA in the chromosome is immersed in the cytoplasm, example - bacteria - Eukaryotic cells - all cells possessing nuclei such as vertebrate cells although mature RBCs in mammals lose their nuclei along the way to maturity. Chromosomes reside in a nuclear compartment or nucleoplasm. - All Eukaryotic cells possess the following basic structural features: - Plasma Membrane - a thin membrane forming outer surface of cell. - Nucleus - a membranous structure housing the DNA in the chromosomes. - Cytoplasm - a semifluid material contained within plasma membrane and outside the nucleus.

Chromosome structure

- Chromosomes are different in structure in G1 and G2. In G1, they are unduplicated and in G2, they are duplicated with sister chromatids being held together by a centromere.

Connective tissue

- Connective tissue is found throughout the body. Its major function is to hold tissues together. Some types of connective tissue have a generalized role in the support and protection of organs. Others, such as bone and blood, have very specialized functions: bones provide muscle attachment, and blood facilitates the transport of nutrients and the removal of waste.

DNA organization in chromosomes

- DNA is contained in the chromosomes which also have proteins attached to the DNA strand. - If all the DNA strands from just one nucleus in one of our cells was removed and if we could tie together all the strands from the 46 chromosome into one long thread, the length of DNA would be over 6 feet! - It would be an extremely thin thread but if it wasn't organized in some way in the chromosomes, it would be quite a tangle of DNA strands. - The key protein family that helps organize DNA are the histones. Histones organize the DNA into circular loops called nucleosomes which with other proteins help form compact regions for easier separation during cell division.

Diffusion and osmosis

- Diffusion - molecules in air or solution tend to move apart until contained in equal concentrations throughout the medium. Molecules move according to the concentration gradient, from high concentration to low concentration. Example - drop of dye in solution of water or perfume in a room. - Osmosis - movement of water through a semi-permeable membrane from an area of low concentration to an area of high concentration of solute which results in a pressure referred to as osmotic pressure. - Semipermeable membrane - membrane permeable to water but not other molecules in solution. - Solute - molecules other than water dissolved in a solution - Osmotic pressure - the actual pressure that water exerts on the side of the membrane with the higher solute concentration as it moves through the semi-permeable membrane. - Tonicity - refers to the relative concentration of solutes in two solutions: - Hypertonic solution - one that draws water out of a cell such as an RBC and causes RBC shrinkage or crenation. (higher concentration outside cell) - Hypotonic solution - one that causes water to move into a cell such as an RBC, causing swelling and eventual breakage called hemolysis. (lower concentration outside cell) - Isotonic solution - one causing no cell swelling or shrinkage. (equal concentration outside and inside cell)

Passive and active transport

- Diffusion - substances move across a membrane by following concentration gradient from area of high concentration to area of low concentration. No membrane receptor required for diffusion across membrane. - Passive Transport - substances able to pass through membrane via diffusion, i.e., by following concentration gradient from high to low concentration. Receptor molecule needed in membrane to assist diffusion across membrane. - Active Transport - energy in the form of ATP used to move solutes across membrane against the concentration gradient. Receptor molecule in membrane required for this type of transport. - For a visual example comparing diffusion, passive and active transport, see your onlinecourse text book. - Exocytosis - vesicle transport of material to outside of cell, i.e., secretion. Also view your online text book. - Endocytosis - bringing outside material inside cell, i.e., phagocytosis.

Mitosis

- During mitosis, chromosomes attach to a spindle apparatus composed of microtubules which is a kind of scaffolding to attach and separate chromosomes into two cells. Spindle apparatus is held in place by two centrioles at each end. (See online A & P text - Cell Membrane module in Cell Biology section) - Mitosis is nuclear division and consists of four stages recognized with light microscopy. - prophase -> metaphase -> anaphase -> telophase (See Mitosis section in Cell Division portion of Cell Biology module in online text.) - Important points about mitosis: - . During metaphase, chromosomes attach as individual chromosomes to the spindle apparatus by the centromere. - . During anaphase, sister chromatids separate by centromere splitting so that each new cell gets 46 different chromosomes. - Cytokinesis is division of cytoplasm after mitosis and is caused by microfilaments forming a "pursestring arrangement" that pinches outer cell membranetogether to form two cells. (See Cytokinesis section of Cell Division portion of Cell Biology module in online A & P text) - Use of drug, cytochasin B, which causes microfilaments to disassemble, can stop cytokinesis without inhibiting mitosis because mitosis is based on microtubules.

Embedding

- Embedding involves the following: correctly oriented specimens are fixed and encased within a suitable medium, providing them with elasticity and ensuring they are supported during sectioning and subsequent analysis.

Endocrine glands

- Endocrine glands lack ducts. They are made up of a hollow, spherical follicleslined with secretory epithelial cells. Each follicle is surrounded by an extensive capillary network. They produce hormones which are secreted into interstitial fluid and diffuse into the surrounding capillaries. Examples include the thyroid, parathyroid, pineal, pituitary, and suprarenal glands. - NB. As the anatomy of the endocrine glands is highly specific, the glands, their histology, function, regulation, and the hormones they secrete, are covered in more detail in the Endocrine Systemsection.

Enzymes

- Enzymes are mostly protein with the exception of an RNA enzyme. Enzymes act as catalysts by speeding up a reaction without being consumed or changed - Substrate - molecule acted upon by an enzyme. - End Product - what substrate becomes after being acted upon by an enzyme - Intermediate - substances formed after substrate is acted upon by enzyme and before it becomes an end product. - Enzyme exhibits specificity for particular substrate(s) because it has an active site, a site on the surface of an enzyme that binds to the substrate in a specific way. - Enzymes in our body increase in activity until they reach too high a temperature and then they denature. - Enzymes are also sensitive to pH and most work best around 7.35 - 7.4 except pepsin, the enzyme secreted by the stomach which works best around pH 1 in stomach acids. - Coenzymes - factors derived from vitamins that are needed for some enzymes to act properly. Some cofactors are needed for oxidation-reduction reactions to occur such as NAD+ (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide).

Epithelium

- Epithelium (epithelial tissue) overlies many body surfaces. It forms a cover as the outer epithelial layer of organs, such as the skin, and a lining as the inner epithelial layer of the wall of a hollow organ or tract, such as the gastrointestinal tract. - The cells constituting epithelium are arranged into continuous sheets, held tightly together by adhesive cell junctionsbetween the lateral surfaces of the epithelial cells. Epithelial cells are secured to the surface they cover by specialized structures called hemidesmosomes. The hemidesmosomes firmly anchor the epithelial cells to a thin underlying sheet of collagen and other fibers which covers surface and cavities of organs known as the basement membrane and to the surrounding extracellular matrix. The epithelium always has a free apical surface, often featuring cilia or microvilli, facing either a body surface or cavity, or the lumen of an organ, tubular duct or vessel. - Epithelial tissues have a number of characteristics: 1. Epithelium is avascular, with no blood vessels entering between the cells. The cells are maintained via blood vessels lying deep within the basement membrane. 2. Unlike connective tissue, epithelial tissue is highly cellular, with little extracellular material. 3. Epithelium that covers or lines organs often has a high regenerative capacity. This allows the epithelial layer to be maintained, despite the continuous sloughing off of cells, for example from the surface of the skin - Epithelial tissues may function as: 1. Selective absorptive barriers, regulating the movement of substances into and out of the body. 2. Secretory surfaces, comprising the functional units of glandular secretion. 3. Protective surfaces, such as the skin. - Epithelial tissues are classified structurally based on cell shape and tissue thickness, and functionally on whether they form coverings and linings or are secretory (glandular).

Epithelium

- Epithelium is found covering and lining the surfaces of the body and organs. There are many different types, with different functions, ranging from protection of the body, to facilitation of the absorption of nutrients.

Exocrine glands

- Exocrine glands consist of a glandular portion, lined with secretory glandular epithelium, and a duct portion, lined with simple cuboidal or columnar epithelial cells. They secrete their non-hormone products (serous or mucous) via ducts to a tissue surface. Examples include sweat glands, goblet cells, digestive glands, and sebaceous/oil glands.

Alternative energy sources in body

- Fats- between meals or when one fasts, fats are broken down to triglycerides which enter mitochondria as acetyl-CoA and produce a great deal of ATP. - Proteins- Excess protein is broken down to amino acids which enter Krebs Cycle to be metabolized to CO2 and H2O. Amino groups are modified to produce urea to be excreted in urine by kidneys. - Glycogen- is broken down to glucose to be metabolized starting with glycolysis and depending on the presence of oxygen, products will move on to the Krebs Cycle or in the absence of oxygen, products will form lactic acid (lactate fermentation as in oxygen depleted muscle cells).

Fixation

- Fixation takes place early on in tissue preparation, to prevent the specimen from undergoing physiological changes. Fixatives help to deactivate internal enzymes within the cells to prevent degradation from within. In addition, fixation can help to increase the mechanical strength of the tissue and reduce the growth of microbe colonies. - A range of different methods of fixation exist, such as chemical perfusion and heat fixation. The method and specific chemicals used are determined by the nature of the target to be visualized.

What is a gene in terms of molecular biology?

- For most genes, a gene is a linear sequence of bases that carries the information or code for a linear sequence of amino acids in a protein. - Other genes carry the code for the linear sequence of bases in RNA molecules some of which make up the ribosomes and other important RNA molecules involved in protein synthesis.

Interphase periods

- G1 - time after cell division in which cell is preparing to duplicate DNA (chromosomes) - S - time during cell cycle that DNA and chromosomes are being duplicated - G2 - time after S period when cell is beginning to prepare for mitosis and cytokinesis.

Glands

- Glands are groups of specialized epithelial cells that function to secrete products either onto a body surface, or into the blood, either directly, or via a duct. The cells which secrete the gland products are glandular epithelium, whereas the epithelial cells that form the ducts (when present) are covering and lining epithelium. Glands may be classified as either exocrine or endocrine

overview of ATP production

- Glycolysis - breakdown of glucose to pyruvic acid and then to lactic acid, if no oxygen is present. Glycolysis is an anaerobic reaction sequence, i.e., - Glycolysis uses 2 ATP molecules and produces 4 ATPs for a net gain of 2 ATP for each Glucose molecule metabolized to pyruvic acid. - ATP is used for synthetic reactions and homeostasis by employing phosphorylation reactions in which the phosphate group on ATP is transferred with release of energy to another molecule. - Kreb's Cycle - is an oxidative circular reaction sequence in which carbon dioxide is produced as well as reduced NADH and FADH2.

Histological techniques

- Histological techniques: There is a wide variety of histological techniques that have greatly enhanced our understanding of anatomy and physiology at the cellular level. Light microscopy, combined with various cell stainingtechniques, has been the fundamental basis of histology for many years, and continues to be a vital technique in research and medicine today. Added to this there is a multiplicity of modern investigative methods, includingimmunohistochemical techniques and electron microscopy, all of which are further extending our understanding of the structure and function of cells. - Samples taken for histological analysis must be correctly prepared. The steps for the preparation of specimens for study by standard light microscopy include: obtaining a sample with the proper orientation, fixing or preserving the specimen, embedding the specimen in support medium, sectioning the specimen into thin slices, staining the specimen for visualization, and microscopic examination of the specimen.

Light (optical) microscope

- How does it work? - Uses beams of visible wavelengths of light, focused through glass lenses, to produce magnified images. - Magnification: Up to 2000x - Lens: Glass - Uses: Ability to view color proves useful for different staining techniques.Relatively low cost renders them more popular within the education and medical sectors - Stains used: Stains highlight tissue/cellular components in different colors. Chromatic dyes used. - Disadvantages: Limited magnification and depth of field - Types: Simple (one lens), compound (many lenses), and digital light microscopes

Electron microscope

- How does it work? - Uses particle beams of electrons, focused through magnetic lenses and metal apertures, to produce highly magnified 2D and 3D images. - Magnification: Up to 2,000,000x - Lens: Electrostatic/electromagnetic - Uses: Used to visualize smaller structures not visible by light microscopy. Allows 3D visualization of structures. Is used in observation of dry, fixed specimens of micro-organisms, cells, large molecules, biopsy samples, metals, and crystals etc. - Stains used: Stains highlight tissue by increasing electron absorption.Electron-dense heavy metals often used. - Disadvantages: Expensive to build, maintain, and run. Very sensitive to vibrations and external magnetic currents.More elaborate preparation of specimens often needed and specimens must be dry.Not possible to observe living specimens or color. - Types: Transmission electron microscope (TEM) for 2D images, and scanning electron microscope (SEM) for 3D images.

Known facts leading to an understanding of DNA structure:

- In early 1950's, a number of scientists were racing to determine the structure of DNA. They knew then that DNA was composed of nucleotides made up of four types of bases called Adenine, Thymine, Cytosine and Guanine or, for short, A, T, C and G. - They knew DNA was in the nucleus and made up the core of chromosomes. - They also knew that when DNA was analyzed for its base content, the amount of A always equaled the amount of T and C always equaled G. - They also knew that the ratios of A/T and C/G were different for different species indicating a species difference in their DNA content. - In those days, many scientists thought that protein was probably the carrier of genetic information because there were so many different kinds of proteins and it was difficult to imagine how DNA could (1) carry information specific to determine genetic traits and (2) how DNA could transfer that information to the offspring. - Watson and Crick eventually solved the problem with the help of some X-ray crystallography data from Rosalind Franklin who was working in the lab of Maurice Wilkins. Franklin's data indicated a regularity of bases and a pairing of them and with this data, Watson and Crick constructed the first model of DNA that explained how information was stored and how it could be transmitted with high fidelity to the next generation.

Regions of the abdomen

- In order to easily describe the location of organs within the abdomen, two vertical lines and two horizontal lines can be used to divide it into nine regions - The vertical lines, the midclavicular lines are positioned using the middle of each clavicle as a reference. - The upper horizontal line, the subcostal line, is positioned at the level of the pylorus of the stomach close to the subcostal margin of the ribs - the lower horizontal line, the intertubercular line, is positioned at the level of the tubercles of the iliac crests of the hip bones.

Important bons in Biological molecules

- Ionic Bonding - occurs when an electron is captured entirely by one of the elements in a compound such as in Sodiu m Chloride and each element is then called an ion. This type of bond in which the electron is completely captured by the other element is called an IONIC BOND. - Covalent Bonding - occurs when electrons are shared by two atoms such as in hydrogen, oxygen, nitrogen and water. - Hydrogen Bonding - when a hydrogen atom is participating in a polar covalent bond so that it is slightly positive in charge, it may form a bond with another electronegative atom such as oxygen. Example = water.

Cell size and shape

- Large cells exist such as a hen's egg (yolk region), frog's eggs and fish eggs such as caviar. - Most cells are microscopic such as RBCs, sperm, muscle cells and nerve cells. We can see the organs that are muscles and nerves but there are many cells which make up muscles and nerves.

Lipids

- Lipids are greasy or oily compounds that dissolve in each other but not water. They are hydrophobic (water-fearing). - Five types of lipid molecules: - Fatty Acids are long chained hydrocarbons with a carboxyl group on the end making it acidic. Find fatty acids linked to other molecules in cell membranes. - Neutral Fats or Triglycerides are have up to three fatty acids attached to a single glycerol molecule, examples are butter, lard and oils. - Phospholipids are two fatty acids attached to a glycerol molecule which is attached to a hydrophilic compound containing a phosphate group. These are interesting molecules because they have both hydrophilic and hydrophobic properties and form cell membranes. - Waxes are long-chain fatty acids that are solids at room temperature. The ear canal produces waxy substance. - Sterols usually have four fused ring compounds and are an essential part of cell membranes. Cells use sterols to make other substances such as Vitamin D, bile salts, and steroid hormones such as testosterone and estrogen.

Meiosis

- Meiosis occurs only in sex germ cells and produces haploid cells from diploid germ cells. - Important distinguishing points between meiosis and mitosis. - . During prophase, homologous chromosomes pair up to form tetrads (two chromosomes having four chromatids). One member of a homologous pair has been contributed by the mother and the other by the father. For the sex chromosomes, the X and X or X and Y chromosomes would form a homologous pair. In females, all chromosomes that pair up will look like each other but in males, the X and Y chromosome will look different but are still homologous because they pair up. - . During meiotic division 1, homologous chromosomes separate without centromere splitting producing haploid cells. - During meiotic division 2, now each individual chromosome in the haploid cell attaches to spindle apparatus and by centromere splitting, sister chromatids move to form two more haploid cells - See Meiosis I and Meiosis II section of Cell Division portion of Cell Biology module in online A & P text for more information. - One spermatogonium produces four sperm. - One primary oocyte produces three polar bodies which disintegrate and only one mature ovum or egg. - During meiosis 1, chromosomes exhibit "crossing over" as indicated by the places on sister chromatids where they can be seen to be sticking to one another called chiasmata. - Crossing over permits genes to reshuffle on homologous chromosomes giving rise to new combinations of genes in the offspring. It is this key point that makes the sexual mode of reproduction a success in that offspring from the same parents may vary considerably in their genetic characteristics leading to a greater variety of gene sets and traits which give a greater chance for species survival via natural selection.

Metabolism

- Metabolic Pathways - controlled breakdown or synthesis of molecules in cells. Usually a series of linked reactions that are sped up by the pathways are linear and others may be circular and others may be branched. - Two major types of metabolism: - Anabolism - synthetic reactions in cells (making larger molecules from smaller) - Catabolism - degradative reactions (breaking larger molecule down to smaller) - Redox reactions - are reactions in which oxidations and reductions occur. Oxidation is a reaction in which a molecule gives up an electron or a hydrogen ion. Reduction is when a molecule accepts an electron or hydrogen ion. When one molecule is oxidized, another molecule is reduced. EXAMPLE

Nucleotides and nucleic acids

- Nucleotides are the basic building blocks for the nucleic acids, DNA and RNA. - DNA structure. (see digital text book Online Anatomy & Physiology)

Protein structure

- Primary Structure - sequence of amino acids in a protein held together by peptide bonds. - Secondary Structure - structure formed from hydrogen bonding. - Tertiary Structure - Interaction of R-groups that can be hydrophobic or hydrophilic. - Quaternary Structure - some proteins interact with subunits (other smaller proteins that come together to form a larger protein structure) such as Hemoglobin. Disulfide bonds help hold protein subunits together. - Other complex proteins exist such as lipoproteins and glycoproteins. Lipoproteins are proteins attached to lipids in blood, for example, and glycoproteins have oligosaccharides attached to the protein component. Glycoproteins form outer cell surfaces and are part of secreted protein products. - Denaturation - breaking of weak hydrogen bonds in protein to destroy three dimensional structure and precipitation in solution

Pseudostratified epithelium

- Pseudostratified epithelium consists of only one layer of cells, but falsely appears to be composed of multiple layers, due to the irregularity in the positioning of the nuclei of the epithelial cells. In fact, not all epithelial cells reach the apical surface, but all cells touch the basement membrane. As a result, this is not true stratified epithelium, and is therefore described as pseudostratified. Pseudostratified epithelium may be ciliated or non-ciliated. - Ciliated pseudo-stratified columnar epithelium: This epithelium is composed of a single layer of columnar epithelial cells. This type of epithelium lines the majority of the upper air passages of the respiratory system, such as the trachea and the bronchi. Here, it is known as respiratory epithelium. Mucus produced by the goblet cells forms a film which lines the respiratory air passages and traps foreign particles that may have been inhaled. Cilia then move in a wave-like pattern, pushing the mucus and any trapped foreign particles towards the pharynx, where it is swallowed. This system is called the mucociliary escalator. Under normal circumstances, an individual in unaware of the movement of mucus, but if large amounts of it are produced, for example as a result of irritation, the mucus can also be coughed out. - Ciliated pseudostratified columnar epithelium also comprises the sensory epithelium of the olfactory area. - Non-ciliated pseudostratified columnar cells are rare. In addition to the epithelial cells lacking cilia, this type of epithelium also lacks goblet cells. It has both absorptive and protective properties and is found in the membranous part of the male vas deferens.

Recombination DNA & genetic engineering

- Recombinant DNA Technology - describes what scientists do when they snip pieces of DNA from one species and insert that DNA piece into the DNA of another organism such as a virus, bacterium or mammal. - The new piece of host DNA which contains the piece of foreign DNA is called recombinant DNA (recombined DNA). - All the ways that scientists now can insert foreign DNA into the DNA of other organisms is referred to as genetic engineering. - Recombinant DNA first began by using bacteria which have, in addition to their one circular DNA molecule (chromosome), a smaller circular DNA molecule called a plasmid. - Recombinant DNA technology is possible because of the discovery of a class of enzymes called restriction endonucleases. - These enzymes snip DNA so that they produce "sticky" ends which can combine with the sticky ends of DNA pieces from other organisms in the presence of DNA ligase. - This techniques may be used to set up a DNA Library which is the entire genome of another organism cut up into pieces and inserted into plasmids of bacteria.

Scientific method

- Science generates new knowledge and solves problems by using the scientific method. The scientific method follows the following steps in designing and performing experiments. Check out the steps below and then look at an actual experiment which demonstrates how the scientific method can be put into action to test an hypothesis. 1. Observe Phenomenon and pose Question 2. Make Hypothesis (Educated guess) 3. Make Prediction (what should you observe) 4. Design and do experiment. 5. Results may support or refute hypothesis 6. Redesign hypothesis and start process again Example: RBC growth in tissue culture with erythropoietin. Observation: Erythropoietin injected into humans with low RBC counts can stimulate RBC production. Hypothesis - Epo (erythropoietin) stimulates RBC stem cells to become mature RBCs Experiment - grow human bone marrow in soft-gel tissue culture with Epo (experimental) and without Epo (control). Results: All plates have culture fluid containing nutrients for growth, similar acidity, bone marrow cells to start and grow for 2 weeks at same temperature.

Sectioning

- Sectioning (microtomy) is the slicing of embedded specimens using a microtome, and the subsequent attachment to a surface (usually a slide) for histological analysis under a microscope. - After sectioning, the slide-mounted sections are dehydrated, stained, and cover-slipped in order to preserve them for repeat microscopic analysis.

Anatomic directions

- Several specific directional terms are used to explain the location of a structure relative to the structures surrounding it. Right and left are also used, but are always described as they are to the subject, rather than as they appear to you - Anterior/ventral: -Anterior: toward the front of the body; in front of - Ventral: towards the belly · -Example: The sternum lies anterior to the heart - Posterior/dorsal: · Posterior: towards the back of the body, behind - Dorsal: towards the back - Example: The heart lies posterior to the sternum - Superior/cephalic/cranial: - Superior: above, on top of - cephalic/cranial: towards the head - Example: the heart lies superior to the diaphragm - Inferior/ caudal - Inferior: below, underneath - caudal: towards the tail - Example: the diaphragm lies inferior to the heart - Lateral: - Away from the mid line of the body, towards the sides - Example: The lungs lie lateral to the heart § Medial: - Towards the mid line of the body, towards the middle. Median refers to the midline - Example: the heart lies medial to the lungs - Proximal: - Nearer to the trunk of the body - Example: the shoulder is proximal to the elbow - Distal: · Furthest from the trunk of the body - Example: the wrist is distal to the elbow - Deep: - Away from the body surface, towards the inner body - Example: The heart is deep to the sternum - Superficial: - Towards the external surface of the body - Example: the sternum is superficial to the heart

Simple epithelium

- Simple epithelium consists of a single layer of epithelial cells that cover, or line, body surfaces. Its presence is important for the facilitation of diffusion, osmosis, filtration, secretion, and absorption. There are a number of types of simple epithelia: - Simple squamous epithelium: Simple squamous epithelium is composed of a single layer of flat epithelial cells, each containing a flattened, centrally located nucleus. It is found at sites within the body where diffusion and filtration take place, for example, the gas exchange surfaces of the lungs and the lining of blood vessels. - Endothelium is the simple, squamous epithelium lining the heart, blood vessels, and lymphatic vessels. In capillaries, the endothelial cells act as a selective barrier, permitting various substances to move from the blood into the interstitial fluid. In larger vessels, the endothelium forms a smooth surface over which the blood can flow without turbulence. - Mesothelium is also simple, squamous epithelium but it has a different embryological origin to endothelium. Mesothelium constitutes the epithelial layer of serous membranes, such as the pericardium, pleura, and peritoneum. - Simple cuboidal epithelium: Simple cuboidal epithelium is made up of a single layer of approximately cube-shaped epithelial cells, each containing a spherical, centrally located nucleus. It is found at sites within the body where secretion and absorption take place, for example, the proximal and distal convoluted tubules of the kidney, and within the thyroid gland. - Simple columnar epithelium: Simple columnar epithelium consists of a single layer of column-shaped epithelial cells, each with an oval nucleus near its base. There are two types of simple columnar epithelium: non-ciliated and ciliated. - Non-ciliated simple columnar epithelium: Non-ciliated simple columnar epithelium is made up of simple columnar epithelial cells which often have microvilli at their apical surface. Microvilli are small protrusions of the plasma membrane of the cell that serve to increase the surface area of the available for absorption or secretion. Interspersed between these columnar cells are goblet cells, which are specialized epithelial cells that secrete mucus at their apical surface. Finger-like microvilli increase the surface area of the plasma membrane, while secreted mucus serves to lubricate and protect the linings of functional tracts, such as the small intestine and the gall bladder. - Ciliated simple columnar epithelium: Ciliated simple columnar epithelium is made up of simple columnar epithelial cells with cilia at their apical surface. Cilia are motile organelles which project from the cell body. The ciliated columnar cells are interspersed with mucus-secreting goblet cells. This type of epithelium is found in a variety of locations, including the lining of the uterine tubes, where the beating of the cilia is responsible for the movement of the egg from the ovary to the uterus.

Cells and organelles

- Space inside eukaryotes (cells with nuclei) is divided up into compartments to permit cell reactions to occur separately from each other. (See Types of organelles: also see onlineyour course text for more discussion of the following organelles.) - Nucleus - has nucleus, nuclear membrane, chromosomes (DNA + proteins). - Endoplasmic reticulum or ER - two types, rough ER which is ER + ribosomes with a function to synthesize proteins. - Smooth ER - ER with no ribosomes, function to synthesize lipids, deactivate drugs, store Calcium in muscle. - Golgi Body- flattened membrane sacs which modify proteins by adding sugar molecules to them and package them for transport out of the cell (exocytosis). - Lysosomes - small vesicles with powerful enzymes in them to degrade foreign material. (suicide bags). Peroxisomes- membranous sacs containing enzymes that break down fatty acids, amino acids, hydrogen peroxide and alcohol. - Mitochondria- double membranous structure that makes most of the ATP that the cell uses for synthetic and maintenance reactions. Knobs on interior membrane are essential to making ATP. Brown fat mitochondria in bats do not have knobs on their mitochondria and generate only heat to assist in bat coming out of hibernation. - Cytoskeleton- microtubules are made of protein subunits called "tubulin", formation of microtubules from tubulin subunits is example of self-assembly. Microfilaments - made of protein subunits called actin, they have contractile ability. Serve as ring around dividing cell membranes to squeeze membrane together to divide cell into two cells. Drug called Cytochalasin B dissociates microfiliaments and can stop cells from dividing into two cells. - Flagellum and cilia show a 9 + 2 array of microtubules present in cilia or flagellum. Cilia line respiratory tract and beat to remove debris, flagellum present as sperm tail for motility. Both are held in place by a basal body, a site of presence for many microtubules acting to anchor cilia or microtubule in place.

Orientation

- Specimen orientation during histological analysis is important for visualizing the true morphology of a structure. This is because improper orientation may cause the tissue to become damaged during the later stages of preparation. Most tissues are embedded flat, with a margin of embedding medium surrounding them for support. During sectioning, the tissue should be oriented in a way that results in least resistance to the knife. A variety of marking systems can be used to ensure correct orientation. - Certain tissues, such as the following, may require a specific orientation: - Tubular structures: Structures that have a tubular morphology, such as sweat gland ducts or blood vessels, are usually cut to display the cross-section of the lumen. - Epithelial biopsies: Biopsies of epithelia, such as the skin or the intestines, are cut in a plane at right angles to the surface, and oriented in a certain way so that the knife cuts from the basement membrane through to the apical epithelial membrane. This way, compression and distortion of the epithelial surface is minimized. - Muscle biopsies: Sections of muscle may be cut in transverse or longitudinal planes. - Multiple tissue samples: To facilitate comparison, multiple tissue samples are oriented similarly, side by side, with, for example, the apical epithelial surfaces all facing in the same direction.

Stratified epithelium

- Stratified epithelium consists of multiple layers of epithelial cells that cover, or line, body surfaces. Its presence is important for the protection of underlying tissues in regions susceptible to greater wear and tear. Types of stratified epithelium include: - Stratified squamous epithelium: Stratified squamous epithelium consists of multiple layers of epithelial cells, ranging from flat, squamous epithelial cells at the apical surface, to more cuboidal/columnar epithelial cells towards the basal surface. Cells at the basal surface are continually dividing, creating new epithelial cells which push the cells up towards the apical layer to replace cells as they are sloughed off. Stratified squamous epithelium may be keratinized or non-keratinized. 1. Keratinized stratified squamous epithelium contains a protective waterproof layer of the fibrous protein keratin, which forms the superficial layer of the skin. This helps to protect the body from temperature extremes, microbes, and damaging substances. As the epithelial cells move towards the apical layer (and further from the blood vessels lying deep to the basement membrane) they begin to receive inadequate nutrition and also become packed with keratin. As a result, they dehydrate and eventually die. Dead epithelial cells lose their connections to adjacent cells and are sloughed off from the apical surface, leaving the underlying cells exposed. 2. Non-keratinized stratified squamous epithelium doesn't contain keratin and therefore the epithelial cells in its apical layers remain properly hydrated and still contain organelles. It forms moist linings such as in the mouth, esophagus, and part of the cervix, where it protects the body against microbes. - Stratified cuboidal epithelium: Stratified cuboidal epithelium consists of multiple layers of epithelial cells, with the apical layer being made of cuboidal epithelial cells. It is a rare type of epithelium with protective, and sometimes secretory and absorptive, functions, and is found in areas such as the ducts of sebaceous glands, sweat glands,mammary glands, and salivary glands. - Stratified columnar epithelium: Stratified columnar epithelium consists of multiple layers of epithelial cells, with cells in the basal layer being short and irregularly shaped, and cells in the apical layer being columnar. It has protective and secretory functions, and it too is rare, found in the ocular conjunctiva of the eye and lining ducts of the larger salivary glands, such as the parotid gland. - Transitional epithelium: Transitional epithelium has a varied appearance, due to its ability to change shape with the tissue that it lines or covers. In its resting state, it resembles stratified cuboidal epithelium but with larger, more rounded cells in its apical layer. When the tissue it lines (or covers) becomes stretched, transitional epithelium takes on the appearance of stratified squamous epithelium, with its cells becoming flatter and more elongated under tension. Transitional epithelium forms a lining which is largely impermeable to water, and is found in tissues that expand and contract, such as the urinary bladder.

What is structure of DNA and how does it replicate?

- Structure is two long DNA strands wrapped in a double helix arrangement. The base pairs (A-T and C-G) are in the middle of the double helix forming a kind of stairway and the sugar-phosphate linkage forms the backbone structure on the outside of each DNA strand. - DNA synthesis is considered to be semiconservative because each strand synthesizes a new copy on itself and thus each new strand is composed of one old strand and one new strand. Conservative replication would mean that the new DNA molecule would have two new strands and the original DNA molecule would have two old strands. - Synthesis of DNA occurs by using enzymes termed DNA Polymerases and other proteins help to unwind the DNA and keep it in the open state so synthesis on a new strand can occur. - DNA Repair in the human body occurs regularly because DNA is exposed to damage from some chemical reactions or ultraviolet radiation (UV light). In the genetic disorder called xeroderma pigmentosum, DNA repair enzymes are missing in the skin cells and every time the skin is exposed to sunlight which has UV light in it, some DNA gets damaged and these people get skin tumors and skin cancer. Heavy tanning even in normal people over time can cause skin cancer likely by the same mechanism.

Fluid mosaic model for membrane structure

- The cell membrane is made up of lipid and also protein. The Fluid Mosaic Model for membrane structure gives an overall structural description of - The cell membrane is described as having a "fluid" as well as a "mosaic" nature. The "Fluid" in the model name refers to the observation that molecules embedded in the membrane such as proteins are not held in one spot but can move around throughout the lipid bilayer just like an iceberg moves throughout the surface of the oceans. - The term "Mosaic" in the model name refers to the mosaic-like arrangement of proteins in the membrane lipid bilayer, i.e., the proteins can be viewed as bumps on the surface of the cell membrane spread in a mosaic-like pattern. - Let's look at the molecular make-up of the plasma membrane in the Fluid Mosaic Model in the following animation. - Protein Components found in plasma membrane: - Adhesion Proteins - assist cells in sticking to each other. - Transport Proteins - help to transport molecules across the membrane both inward and outward. - Receptor Proteins - proteins which can bind to molecules like hormones and can then cause changes to occur inside the cell. - Recognition Proteins - proteins which recognize other cells like itself so they can bind together.

Covering and lining epithelium

- The classification of covering and lining epithelium is based on the following. 1. The three-dimensional shape of the epithelial cells comprising it, as observed by light microscopy. 2. The way in which the epithelial cells are arranged into layers. - Epithelial cells vary in shape depending on their function and location. They may be: -. Squamous: Flat, plate-like cells. - Cuboidal: Cube-like cells, with a similar height, width, and depth. - Columnar: Column-shaped cells, with a height two to three times greater than their width. - Transitional: Some cuboidal or columnar cells have the ability to change shape during stretching and compression. If the organ or tubule they line is not being stretched, they are cuboidal or columnar in appearance; when stretched, they become squamous in appearance. - Epithelial tissues are classified based on the number of cell layers and cell morphology (cell shape). If only one cell layer is present, the epithelium is referred to as simple. If two or more cell layers are present, the epithelial tissue is called stratified. - Simple epithelium: A single layer of cells are anchored to the underlying basement membrane. - Stratified epithelium: Multiple layers of cells, where only the bottom layer of epithelial cells is anchored to the underlying basement membrane. - n addition, some epithelium is described as pseudostratified. - Pseudostratified epithelium: Cells appear to be arranged in layers, but careful observation reveals that all cells are anchored to the underlying basement membrane

Water chemistry

- The human body is composed of about 2/3 water. - All of the chemical reactions in our bodies take place in watery fluids - Polar molecules such as salts dissolve in water and non-polar molecules such as lipids do not like water and float on the surface. Example = NaCl in water. - Polar molecules (NaCl) that dissolve in water are termed HYDROPHILIC ("water-loving"). - Non-polar molecules (i.e. salad oil) that do not dissolve in water are termed HYDROPHOBIC ("water-fearing").

Frozen sections

- The process of fixing and embedding specimens in paraffin wax causes damage to some labile cellular components, such as enzymes, therefore, freezing is often a good alternative. Specimens are rapidly frozen by immersion in liquid nitrogen so that the tissue hardens into a solid mass. The frozen specimens may then be finely sectioned using a refrigerated microtome (cryostat). Frozen sections may be used for cellular localization of specific enzymes and soluble lipids, or in the identification of substances using immunohistochemistry. - Specimens are also frozen during surgical procedures, where histological analysis may be needed, but where traditional paraffin embedding would be too time consuming. This is of particular use in determining the malignancy of tumors discovered during surgery.

Major body cavities

- There are two main cavities within the body, the dorsal and ventral cavities - Dorsal cavity: - The dorsal body cavity lies posteriorly and is the smaller of the two cavities - It can be further divided into superior and inferior portions, the cranial cavity and the vertebral canal respectively - Cranial cavity: The superior portion of the dorsal cavity. It is bound by the skull and contains the brain and meninges - Vertebral canal: The inferior portion of the dorsal cavity, also known as the spinal cavity. It is bound by the vertebral column, intervertebral discs and surrounding ligaments and contains the spinal cord and spinal nerve roots - Ventral cavity: - The ventral body cavity lies anteriorly and is the larger of the two cavities - It can be further divided into three cavities: the thoracic cavity, abdominal cavity, and pelvic cavity. The thoracic and abdominal cavities are divided by the diaphragm and the abdominal and pelvic cavities are continuous with each other - Thoracic cavity: A large cavity bound laterally by the ribs and inferiorly by the diaphragm. It contains the mediastinum, pericardium, and pleural cavities. - Mediastinum: The mediastinum is an area found between the pleural cavities. It contains the esophagus, trachea, thymus, pericardial cavity and its contents, the great vessels of the heart, and thoracic lymph nodes. It is bound anteriorly by the sternum and posteriorly by the vertebral column. - Pericardial cavity: A thin cavity surrounding the heart, the pericardial cavity is the potential space between the two layers (visceral and parietal) of serous pericardium. It contains fluid that facilitates the free movement of the heart - Pleural cavity: A think cavity surrounding each of the lungs, it is the potential space between the two layers (visceral and parietal) of pleura. it contains fluid that facilitates the free movement of the lungs - Abdominal cavity: A large cavity found inferior to the diaphragm. It contains the gastrointestinal tract, spleen, kidneys, and adrenal glands. it is bound laterally by the body wall and inferiorly by the pelvic cavity - Pelvic cavity: A small cavity found inferior to the brim of the pelvis. It contains the urinary bladder, internal genitalia, sigmoid colon, and rectum. It is bound superiorly by the abdominal cavity, posteriorly by the sacrum, and laterally by the pelvis

Transcription

- Transcription process differs from DNA synthesis in 3 ways: - only the gene segment on the DNA serves as a template to make the RNA molecule. - RNA polymerases are used to make RNA from DNA - transcription produces a single stranded RNA molecule - See online text for RNA synthesis diagram. - Transcription starts at the promoter region, a base sequence that tells RNA polymerase to start here and make RNA on this part of DNA strand. - Three types of RNA are synthesized: - messenger RNA or m-RNA - carries the base sequence which codes for the amino acid sequence in a protein. - transfer RNA or t-RNA - transfers a specific amino acid to the growing polypeptide chain. - ribosomal RNA or r-RNA - forms the ribosome which is the scaffolding upon which protein synthesis occurs. - Messenger RNA (m-RNA) - the newly formed m-RNA usually contains some lengths of RNA that must be clipped out before the m-RNA can be functional. These pieces are called introns and the remaining pieces called exons are spliced together to form the functional m-RNA.

Translation

- Translation (RNA -> protein) - Genetic Code - is a triplet code, i.e., 3 bases in a row in a m-RNA molecule called a codon code for the insertion of a particular amino acid in a protein. - example - sequence of m-RNA bases C-G-U codes for insertion of amino acid arginine and G-G-U codes for glycine. - A-U-G is the base sequence that says "start here" for synthesis of a protein. - U-A-A, U-A-G and U-G-A are all "stop" signals telling enzymes to stop adding more amino acids to the protein. - Each amino acid can have more than one codon (set of three bases determining its place in a growing polypeptide chain). - There are 64 known codons with 61 codons for the amino acids and 3 for stop codons. - These 64 codons are the Genetic Code.

Introduction: Histology

- introduction: Histology is the study of tissues (groups or collections of cells with similar functions) and their cellular components. It allows the examination of cellular arrangements and organization to examine organ structure in terms of form and function, a process known as morphology. Histology is also used in the recognition of pathology and in the discovery of how abnormal biochemical and physiological processes result in disease. - Histologists have categorized the tissues of the body into four major groups based on their components, their appearance under the microscope, and their function. These include:

Role of t-RNA and r-RNA

- t-RNA's are shaped liked "key-holes" with a spot at one end for attachment of a particular amino acid and a 3 base sequence (triplet code) at the other end called an anticodon which pairs with the codon bases for a particular amino acid. - r-RNA comes in two major types which form a small and large subunit that come together to make the functional ribosome. - Translation Steps (three stages - see diagrams in online text.): - Initiation - the small ribosome subunit binds to the m-RNA with the initiator t-RNA (the one with the T-A-C anticodon to attach to the codon U-A-G, start codon on the m-RNA). This complex of small ribosome subunit, m-RNA and starter t-RNA then binds to the large ribosome subunit to form the complete ribosome. - Elongation - charged t-RNAs (t-RNA with its amino acid attached) bind to the second codon and #1 amino acid is linked to #2 amino acid by a peptide bond. The starter t-RNA is released and the entire m-RNA shifts over one codon to leave room for the next charged t-RNA to attach with #3 amino acid ready to be linked to the growing polypeptide. This process is repeated until entire protein sequence of amino acids is in place. - Note that it is the entire polypeptide that is transferred to the single amino acid rather than the reverse during the synthesis stage. - Termination - Occurs when a stop codon is reached (no t-RNA anticodon available) and releasing proteins separate m-RNA and protein from ribosome. Protein then may either join other proteins in cytoplasm or enter the cytomembrane system to be modified by the Golgi Apparatus and secreted by the plasma membrane or incorporated into the cell membrane. - Many ribosomes may be attached to the same m-RNA molecule with polypeptides of differing lengths being translated and this large structure is called a polysome.

ATP

o ATP: - For cells to function normally, they must be able to use energy released by the catabolism of a range of organic molecules to power diverse cellular processes, such as muscular contraction or active transport. This is achieved by the use of adenosine triphosphate (ATP) as an energy transfer molecule.ATP, which is sometimes described as the 'molecular currency' of energy transfer, is produced by aerobic and anaerobic respiration. It can be used as an energy source for almost all cellular processes that require energy. o Structure of ATP - ATP is composed of the pentose sugar ribose, the nitrogenous base adenine (which together form the molecule adenosine), and threephosphate groups. o Function of ATP - Adjacent phosphate groups are linked to each other by high energy phosphate bonds, which are critical for the energy transfer function of ATP.When one of these phosphate bonds is broken in a process catalyzed by the enzyme ATPase, ATP is converted into adenosine diphosphate(ADP) and energy is liberated. This is the source of energy for most cellular processes.The resultant ADP and phosphate group can be converted back into ATP by the enzyme ATP synthase, with the addition of energy supplied by metabolism.These reactions can be summarized in the following equation: -ATP ⇌ ADP + phosphate group + energy - The energy liberated from the hydrolysis of ATP can be used for a myriad of cellular processes. These include the synthesis of large molecules such as glycogen, muscular contraction, the ability of neurons to fire action potentials, and the active transport of substances across cell membranes.

Chemical bonds

o Chemical bonds - Chemical bonds are the forces that hold atoms together in a molecule. There are several types of chemical bonds, which can be responsible for giving a molecule different properties. When atoms form bonds with other atoms, they do so in adherence to the octet rule.The octet rule explains that certain atoms seek out other atoms in order to fill their valence shell and increase their stability. An atom with a full valence shell (eight electrons) is more stable, and is, therefore, less likely to form more bonds. The large majority of biologically significant atoms, however, are 'unstable' in nature, and, therefore, quite reactive. Hence the octet rule can be used to predict their behavior: atoms will bond with other atoms that can compensate for the deficiency in their valence shells. A common exception to the octet rule is hydrogen, which only has one electron. This electron is located in the innermost electron shell which only holds two electrons. Hydrogen, therefore, only requires one additional electron to secure a stable configuration: too few to form an octet. o Molecules and ions - Atoms are able to bond with other atoms of the same or a different kind to form molecules. o molecule: - Atoms can acquire additional stability by sharing electrons with another atom of the same type or a different type. When two atoms join together like this, they form a molecule. For example, a sodium molecule (Na2) consists of two atoms of sodium joined together. - The molecular formula of a substance indicates the elements involved, as well as the number of atoms of each. This is represented by a series of letters (indicating the elements) and subscript numbers (indicating the number of atoms involved). For example, the molecule methane has the molecular formula CH4, indicating that it is comprised of one carbon atom and four hydrogen atoms bonded together. o Representations of molecules - There are many ways in which the structure of a molecule can be represented. These are summarized below: o Electron shell model: - The electron shell model is one of the most common ways to represent the molecular formula of a substance. Each atom is represented by a letter that is surrounded by rings, which represent the electron shells of that atom. The spheres circulating in those rings represent the number of electrons found in that shell. o Structural formulae: Lewis diagram - A Lewis diagram is a shorthand representation of the structure of a molecule. Atoms are represented by letters, and bonds are represented by parallel lines. It demonstrates the carbon skeleton of most molecules but does not give an impression of the 3D structure of a molecule. o Structural formulae: wedge-shaped diagram - The wedge-shaped diagram is a 3D representation of a molecule. It shows the spatial orientation of the bonds in the molecule using different types of line. A wedge denotes a bond that is in front of the plane of the page, a dashed line denotes a bond that is behind the plane of the page, and single black lines denote bonds which lie within the plane of the page. It is a type of perspective diagram o Ball-and-stick model - The ball-and-stick model shows the 3D structure of a molecule and the position of its bonds. It is used to visualize the 3D structure of a molecule as well as its bonds. Atoms are represented by spheres, and bonds are represented by rods. o Space-filling model - The space-filling model shows molecules in 3D and is used to visualize the shape of a molecule. Each atom is represented by a sphere, and the space between two spheres represents the space between the nuclei of two atoms. The disadvantage of this model is that it does not show the bonds between the atoms - Single atoms may also become modified by either gaining or losing an electron to become charged, after which they are known as ions. o Ion: - Ions are charged forms of atoms (which are neutral). The charge is caused by the gain or loss of electrons to or from an atom's outer shell. Gaining electrons causes the atom to become a negatively charged ion or anion, e.g., Cl-, whereas the loss of electrons causes the atom to become a positively charged ion or cation, e.g., Na+. o Anion: - An anion is a negatively charged ion. Anions have more electrons than protons, as they have gained at least one electron in their valence shell. o Cation: - A cation is a positively charged ion. Cations have more protons than electrons, as they have lost at least one electron from their valence shell. o Free radical: - Free radicals are atoms or molecules that have at least one unpaired electron in their outer shell. Free radicals are created through the addition or removal of electrons to or from the valence shell. As a consequence, free radicals are unstable and extremely reactive entities, with the tendency to break and/or damage other molecules and cellular structures in the body. Superoxide is an example of a free radical found in the body. Free radicals stabilize when an electron is donated from another atom, or when their unpaired electron is yielded. o Types of bond: - There are two main types of chemical bond: ionic and covalent. However, a third type of bond, which is formed specifically between hydrogen atoms and other atoms, is called the hydrogen bond. - Ionic bonds: - An ionic bond is a chemical bond between two oppositely charged ions. It is formed by the transfer of one or more electrons from an outer valence shell of one atom to another, so that both have complete outer shells. The subsequent electrostatic attraction of the ions to one another draws them close together, forming an ionic bond. - Example: A molecule of sodium chloride is formed by one sodium ion and one chloride ion, linked by an ionic bond.An atom of sodium has a single valence electron and is highly chemically unstable. If the sodium donates this electron to another atom, it is left with eight electrons in its valence shell. This arrangement is much more chemically stable. Because the sodium now has one fewer electrons than protons, it has an overall positive charge of +1, and is a sodium ion.An atom of chloride has seven valence electrons and is also highly chemically unstable. If the chloride gains an electron from another atom it ends up with eight electrons in its valence shell, which is much more chemically stable. The number of electrons of the chloride is now one greater than the number of protons, so it has an overall negative charge of -1, and is a chloride ion.When a sodium atom donates its single valence electron to a chlorine atom, a positively charged sodium ion and a negatively charged chloride ion are formed. As these ions are oppositely charged, they strongly attract each other, forming an ionic bond. Together, they form the molecule sodium chloride. - Covalent bonds: - Covalent bonds are formed when at least two atoms share their valence shell electrons. Because electrons are shared within covalent bonds, as opposed to being swapped (as in ionic bonds), the bonds formed are much stronger than ionic or hydrogen bonds. The more electrons two atoms share, the stronger the bond. - Example: A molecule of methane is formed from one atom of carbon and four hydrogen atoms.Each atom of hydrogen has only one of two possible electrons in its valence shell, and so is chemically unstable. A carbon atom has only four of eight possible electrons in its valence shell, and is also quite chemically unstable. Rather than gaining or losing electrons to fill a valence shell, one carbon and four hydrogen atoms can complete their valence shells by sharing electrons, and therefore, become more chemically stable. Each hydrogen atom shares its one valence electron with the carbon atom, and the carbon atom shares one of its valence electrons with each hydrogen atom. This allows the carbon atom to have a full valence shell of eight electrons, and each of the four hydrogen atoms to have a full valence shell of two electrons.The sharing of an electron pair between two atoms forms a covalent bond. Each of the four hydrogen atoms is, therefore, covalently bonded to the carbon atom, forming the molecule methane. - Covalent bonds can be single, double, or triple, depending on how many electrons they are sharing. However, within covalent bonds, electrons are not always shared equally as one atom may attract the shared electrons more than the other. - Single covalent bond: - A single covalent bond involves two atoms sharing one pair of electrons. In structural formulae, single covalent bonds are denoted by a single line between each chemical symbol. - Example: Hydrogen molecules, methane molecules - Double covalent bond: - A double covalent bond involves two atoms sharing two pairs of electrons. In structural formulae, double covalent bonds are denoted by two parallel lines between each chemical symbol. - Example: oxygen molecules - Triple covalent bond: - A triple covalent bond involves two atoms sharing three pairs of electrons. In structural formulae, triple covalent bonds are denoted by three parallel lines between each chemical symbol - Example: Nitrogen molecules - Polar covalent bonds - The unequal sharing of electrons results in a polar covalent bond. This is due to the ability of one of the atoms in the bond to attract electrons more strongly than the other. The ability of an atom to attract electrons to itself is called electronegativity. The more electronegative an atom is, the more strongly it can attract electrons. If one atom within the molecule is more electronegative in comparison to the other atoms present in the molecule, it is more able to draw electrons towards itself than the other atoms. The result of this electronegativity is a slightly more negative charge on that atom and a slightly more positive charge on the other atoms. This difference in charges within a molecule is what gives it polarity. - Water: - Oxygen is highly electronegative, meaning that it has a strong affinity for electrons. An oxygen molecule has six electrons in its valence shell, so it seeks two electrons to increase its stability.When an oxygen atom shares electrons with two hydrogen atoms, it forms a molecule of water. As oxygen attracts electrons much more strongly than hydrogen, the electrons shared by the atoms of a water molecule spend a greater amount of time near the oxygen nucleus rather than the hydrogen nuclei. This results in a charge separation in the molecule, where one part of the molecule, the oxygen, has a slightly more negative charge and each hydrogen atom has a slightly more positive charge. As the sharing of the electron pair is unequal, these bonds are known as polar covalent bonds. The difference in charges within a molecule is what gives it polarity. The charge differences cause water molecules to be attracted to each other, the relatively positive areas being attracted to the relatively negative areas. This attraction contributes to hydrogen bonding.Hydrogen bonds are weaker than polar covalent bonds, but give water its cohesion and explain water's high surface tension. The polarity of water also allows other polar molecules to cohere to the water molecules. Polar molecules such as glucose and sodium chloride are strongly attracted to water molecules so dissolve easily in water. They are known as hydrophilic molecules. Molecules that do not contain many polar covalent bonds such as fats and oils do not dissolve easily in water and are not as strongly attracted to water. They are called hydrophobic molecules. - Hydrogen bonds: Hydrogen bonds are weak, polar attractions between hydrogen atoms already involved in polar covalent bonds, and other atoms. They most often occur between different molecules, but they can also form within a molecule if the molecule is very large, such as a protein.Hydrogen bonds form when hydrogen atoms, which are usually partially positively charged, attract the partial negative charge of a neighboring atom.An example of hydrogen bonding can be seen between water molecules. This occurs when the partially positive hydrogen atom of one water molecule attracts the partially negative oxygen atom of another. Hydrogen bonds are not strong enough to bind atoms, as is seen in molecules; however, they can cause cohesion of molecules to each other. In water, this property is referred to as high surface tension. Although individual hydrogen bonds are weak, in large numbers they are a steadfast force which helps to maintain large and complex structures like enzymes and DNA

Chemical composition

o Chemical compositions of matter: - Matter is defined as anything that takes up space, and has a discernible mass. All cells, tissues, and organs in the body are composed of matter arranged in small units, known as atoms. Atoms of the same type are known as elements. o Atom: - Atoms are composed of three main subatomic particles:protons, neutrons, andelectrons. These differ in their mass, position within the atom, and electrical charge. o Element: - The number of protons within an atom identifies it as a particular element and each element has an atomic number that identifies the number of protons at its core.All structures within the body are formed from elements. Currently, there are 117 recognized elements, 25 of which are commonly found in the body. The names of elements are described using a one or two letter abbreviation or chemical symbol. They are organized by atomic number in a table known as the periodic table. o Atomic Structure: - Atoms are considered the basic structural unit of matter. They are comprised of even smaller units, known as subatomic particles. There are three types of subatomic particle: protons,neutrons, and electrons. An atom is defined by the number of protons it contains in the nucleus. Because atoms are electrically neutral, the number of proteins and electrons are equal. The number of protons with the nucleus differs from atom to atom, and is the basis of identification of the atom as a chemical element. o Protons: - Protons are positively charged particles found within the center of an atom, in the nucleus. o Neutrons: - Neutrons are also found within the nucleus; however, they carry no charge and are thus considered neutral. o Electrons: - Electrons are negatively charged particles found moving around in the electron clouds that envelop the nucleus. o Representations of atomic structures: - There are several models used to explain the relative position, size, and number of subatomic particles within a particular atom. These models include the electron cloud model and the electron shell model. The electron shell model is the most commonly used representation. o Electron clouds - Electron clouds represent the large space surrounding the nucleus of the atom. Electrons orbit around the central nucleus of the atom in these electron clouds. o Electron Shells - The electron shell model depicts electrons in a series of concentric circles around the central nucleus of the atom. An atom can have many electron shells, each representing a different energy level. Electron shells farther from the nucleus have a greater amount of energy because the attraction between the positive nucleus and negatively charged electrons is weaker. The number of electrons that each successive shell can hold is finite. The first and innermost electron shell holds two electrons, the second holds eight, and the third can hold up to 18. The electron shells are filled from the inside out, with the outermost electron shell being known as the valence shell. o Periodic table - The periodic table is an organized catalog of known chemical elements. Elements are listed according to increasing atomic number and are arranged in a series of vertical columns and horizontal rows. Vertical columns within the periodic table are known as groups, and elements found within the same group display similar properties. Horizontal rows within the periodic table are known as periods, and elements are arranged in periods according to increasing atomic number (from left to right). Elements found within the same vertical column are said to be in the same group, and are often named according to their similar properties. For example, group 0 elements have a full outer electron shell, and are thus chemically inert. They are also gaseous, and hence known as noble gases. There are 25 elements commonly found within the body (the most important are displayed in the table below). Not all elements, however, are found in the body in their normal state. Some elements, due to other influences in the body, e.g., other atoms or elements, are found in their ionized or charged forms. Ions can be positively charged or negatively charged. Positively charged ions are produced by the loss of one or more electrons. Negatively charged ions are produced by the addition of one or more electrons. Ionization of an element or atom is usually represented by a + or - symbol, e.g., H+ and Cl-. Cations have a positive charge, produced by the loss of one or more electrons. Anions have a negative charge, produced by the addition of one or more electrons. If more than one electron is lost or gained, this is usually denoted by a number, e.g., Fe 2+ and O 2-. o Selected elements: - Hydrogen: - Hydrogen forms approximately 9.5% of total body mass and is found in organic molecules, in water, and as hydrogen ions (H+), which make solutions acidic. - Carbon - Carbon forms approximately 18.5% of total body mass. It is found in the majority of molecules in the body functioning as the backbone of many organic substrates, such as carbohydrates, proteins, and lipids. - Nitrogen: - Nitrogen constitutes approximately 3.2% of total body mass, forming the amine group found in proteins and nucleic acids. - Oxygen: - Oxygen forms approximately 65% of total body mass. It is a constituent of many organic molecules, as part of hydroxyl, carboxyl, and phosphate groups. Oxygen also forms part of many important inorganic molecules, e.g., water. - Sodium: - Sodium in its cationic form (Na+) is an important component of extracellular fluid. It affects the volume of fluid inside and outside of the cells and thus plays an important role in maintaining fluid homeostasis. - Magnesium: - Magnesium is one of the less common elements found in the body; however, in its ionized form, it plays an important role in the structure and action of many enzymes. Over half of the magnesium in the body is present within bone as magnesium salts, the rest forms part of intracellular fluid. Magnesium also contributes to the structure of the sodium-potassium pump. - Phosphorus: - Phosphorus contributes to the structure of teeth and to the matrix of bone tissue as part of the molecule calcium phosphate. Phosphorus also contributes to the structure of nucleic acids, the plasma membrane, and the energy molecule, ATP. - Sulfur: - Sulfur is another of the less common elements found in the body. It contributes to the structure of some proteins, such as insulin, and to vitamins, such as thiamine. - Chlorine: - Chlorine in its anionic form (Cl-) is an important component of extracellular fluid: it affects the volume of fluid inside and outside the cells and, by doing so, helps maintain fluid homeostasis. - Potassium: - Potassium in its cationic form (K+) is an important component of intracellular fluid, helping to maintain the body's normal fluid levels. Potassium plays an important role in maintaining fluid homeostasis and also contributes to the conduction and generation of action potentials. - Calcium: - Calcium contributes to the hardness of bones and teeth. In its ionized form it contributes to excitation-contraction coupling in muscles, to blood clotting, and to the release of neurotransmitters from nerve cells. - Iron: - Iron in its ionized state forms part of hemoglobin (the oxygen-carrying pigment found in red blood cells) and myoglobin (a similar molecule found in muscle cells). It is also a component of some enzymes found in the body. o Atomic number and mass number: - The properties of an atom determine how it will behave around other atoms. Two important factors, the atomic number and the mass number of the atom, primarily dictate how it will behave and where it will sit as an element in the periodic table. o Atomic number: - The atomic number represents the number of protons found in the nucleus of each atom, thus each element has an individual atomic number. For example, the element oxygen has eight protons, and therefore, has the atomic number eight. The number of protons is always equal to the number of electrons. o Mass number: - The mass number of an atom is simply its atomic number plus the number of neutrons found in its nucleus. For example, the atomic number of oxygen is 8, and oxygen has 8 neutrons in its nucleus. Therefore, the mass numberof oxygen is 8 + 8 = 16. It is possible for the same type of atom to have a different number of neutrons. These different forms of the same atom are known as isotopes, as their mass numbers differ, even though their atomic number is the same. This is depicted as the symbol for that element plus the mass number. For example, oxygen has several isotopes with mass numbers 16, 17, and 18. These are depicted as O-16, O-17, and O-18, respectively.The relative atomic mass of oxygen is based on the average of the masses of the different isotopes, which is calculated as 15.9994. This number is commonly simplified to the most prevalent isotope, which in the case of oxygen is 16.

Compounds and mixtures

o Compounds and mixtures: - A substance containing two or more different chemical elements bonded together is known as a compound. All compounds can be broken apart by chemical reactions to form more simple substances. In addition to forming compounds, elements and molecules can collect and mix with one another without becoming chemically bonded. There are many examples of this type of interaction between molecules in the body, one of which is blood. This sort of interaction, where molecules and elements interact physically with one another but do not bond, is known as a mixture. o Compounds: - The body consists of both organic and inorganic compounds. Organic compounds are large compounds that contain one or more carbon atoms. Each carbon atom is linked by covalent bonds to other atoms, which can include hydrogen, nitrogen, and oxygen. Four of the most important organic compounds found in the body are carbohydrates, lipids, proteins, and nucleic acids. Inorganic compounds are small compounds that usually lack carbon in their structure. They possess either covalent or ionic bonds and are much smaller than their organic counterparts. The most common inorganic compounds found in the body include water, and most acids, bases, and salts. Examples of inorganic compounds that contain carbon atoms include carbon dioxide (CO2), and carbonic acid (H2CO3). o Water: - Water is one of the most abundant inorganic compounds found within the body. It forms approximately 50-60% of all of the body's compounds.One of the most important properties of water is its polarity: the uneven sharing of electrons causes partial charges to form near the oxygen and hydrogen atoms, creating a dipole. This property makes water a good solvent, and gives molecules cohesion. Water molecules have a number of other properties, which are described below. o Properties of water: - Solvent: - Water molecules have a characteristic bent, triangular structure that enables them to interact closely with other molecules. This, in addition to their polarity, makes water a good solvent for other polar molecules.A large number of organic and inorganic molecules will dissolve in water creating a solution. Polar molecules that are strongly attracted to water molecules are called hydrophilic molecules, and dissolve easily in water, e.g., glucose and sodium chloride. Molecules that do not contain many polar covalent bonds are not as strongly attracted to water and are called hydrophobic molecules, and do not dissolve easily in water, e.g., fats and oils. - Surface tension: - The polar properties of water mean that water molecules are strongly attracted to one another, creating an inward force known as surface tension.In the body, this can be seen in the alveoli (air sacs) of the lungs, which are coated with a thin layer of fluid known as alveolar fluid, a large component of which is water. The surface tension created by these water molecules contributes largely to the ability of the lungs to recoil after each breath and to expel air from the body. - High heat capacity: - Water has a high heat capacity, meaning that it is able to absorb large amounts of heat without large changes in its own temperature. This is due to the large amount of hydrogen bonds that water molecules form with one another. In the body, this property prevents sudden changes in temperature from both external and internal factors. As a major component of blood, water redistributes body heat to other tissues in an attempt to maintain homeostasis. - High heat of vaporization: - Water also has a high heat of vaporization, meaning that a large increase in temperature is required to transform water from its liquid state into a gas. This property is exploited in the body as a method of evaporative cooling, and explains the body's ability to cool itself through sweating: as water evaporates from the skin, it takes heat with it, cooling the surface of the skin. o Mixtures: - A mixture can occur when molecules and elements mix with one another without forming bonds. All the elements involved in a mixture retain their original properties and can be separated. There are three types of common liquid mixtures: solutions, colloids, and suspensions. o Solution: - A solution is an example of a physically mixed solid, liquid, or gas. Solutions are homogenous mixtures, meaning that the substances combined are of a similar nature. A solution is made of a solute and a solvent. A solvent is described as a substance in which other substances are able to dissolve, and the substance dissolved within a solvent is known as a solute. The solute is present in much smaller amounts than the solvent, and its particles are tiny in size, meaning that they cannot be seen by the naked eye. For this reason, solutions are often transparent. In the body, water is the primary solvent, dissolving a wide range of substances. Water is a good solvent because of its polarity and molecular shape, enabling it to interact with several surrounding ions and molecules. o Colloid: - A colloid is an example of physically mixed solids, liquids, or gases. Colloids contain larger particles than solutions and are heterogeneous mixtures, meaning that the substances combined are of a different nature to one another. The large size of the particles contained within a colloid cause it to appear translucent or cloudy, as the particles scatter light. Milk is a good example of a colloid. o Suspension: - A suspension is another example of physically mixed solids, liquids, or gases. Like colloids, suspensions are also heterogeneous mixtures. They differ in that the solutes present within suspensions are larger and sometimes visible. This means that in addition to the suspension appearing somewhat cloudy, the solutes and solutions often separate and settle out. In the body, blood is a prominent example of a suspension. When still, it separates into layers, with the heavier red blood cells accumulating at the bottom and the lighter blood plasma settling on top of it. Disruption of blood by shaking or mixing will cause the layers to combine once again.

Body systems

o Intro: - There are 11 systems of the human body: the integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive. - Each system has a specific role in helping the human body survive and reproduce. However, in order to work effectively, all systems must work together. For example, reproduction can only occur under the right conditions, whereby the cardiovascular, urinary, and respiratory systems work in unison to supply energy to the reproductive organs. This means that all of these systems are not only inter-related, but are also interdependent. o Integumentary system: - The integumentary system consists of skin and the associated skin components, i.e. hair, sweat glands, sebaceous glands, and nails. - Function: protects the body from the external environment, excretes metabolic waste, helps to make vitamin D, and detects pain, touch, dehydration, and changes in temperature o Skeletal system: - The skeletal system consists of the bones and the cartilage associated with joints - Function: Protects the body, provides support and a framework for muscles to act upon, contains bone marrow for blood cells to develop in, and stores minerals such as calcium o Muscular system: - The muscular system consists primarily of skeletal muscle, but there are also two other types of muscle: Cardiac muscle found in the heart and smooth muscle found within the viscera, including the alimentary canal and the walls of blood vessels - Function: Enables the body to move by the action of opposing muscular contraction and relaxation. It also maintains posture and plays a role in thermoregulation. o nervous system: - The nervous system includes the brain, spinal cord, nerves and special sense organs, e.g. eyes, ears, and taste buds. This system is divided into the central nervous system, containing the brain and spinal cord, and the peripheral nervous system, containing everything else. - Function: the functionality of the nervous system can be split into three main stages: · Detecting changes (sensory function) in the internal and external environment , encoding them into electrical impulses, and transmitting them along the nerves · Processing electrical impulses (integrative function) and making decisions, either consciously or unconsciously · Activating effectors (motor function) to induce and appropriate response to initial stimulus. This can be muscular movement or glandular secretions. o Endocrine system: - The endocrine system consists of endocrine organs and endocrine tissue embedded within organs. Endocrine organs include the pituitary, thyroid, pineal, parathyroid, and adrenal glands. Endocrine tissue is also found within the hypothalamus, pancreas, thymus, gonads, heart, stomach, and small intestine. - Function: Hormones alter the metabolism of target cells. The hormone can be very specific, affecting only one cell type, or very general, affecting many cell types o Cardiovascular system: - The cardiovascular system consists of the blood, heart, and blood vessels - Function: Pumps blood around the body through the blood vessels to deliver oxygen and nutrients to cells and remove metabolic waste. Regulates the water content of body fluids, the acid-base balance, and the temperature of the body. o Lymphatic system: - The lymphatic system consists of lymphatic fluid (lymph), lymphatic vessels, lymph nodes, the spleen, lymph nodules, and thymus. - Function: Responsible for transporting various substances; it takes lipids from the gastrointestinal tract to the blood, and transports protein and fluids back to the bloodstream. It is also responsible for the development of lymphocytes, the cells responsible for fighting disease. o Respiratory system: - The respiratory system consists of air passageways: the pharynx, larynx, trachea, bronchi, bronchioles, and the lungs - Function: Responsible for oxygen/carbon dioxide gas exchange with the blood and also involved in the regulation of acid-base balance and sound production . o Digestive system: - The digestive system consists of the digestive tract: the oral cavity, pharynx, esophagus, stomach, and small and large intestine, as well as organs that assist digestion: the salivary glands, liver, gallbladder, and pancreas. - Function: responsible for the breakdown of ingested food, both physically and chemically, so that nutrients can be absorbed. it is also involved in the absorption of water and removal of undigested food. o Urinary system: - The urinary system consists of the kidneys, ureters, urinary bladder, and urethra - Function: filters blood in order to extract metabolic waste and maintain the acid-base and mineral balance. It also helps to regulate the production of red blood cells. o Reproductive system: - The female reproductive system contains the gonads (ovaries), uterine tubes, uterus, vagina, clitoris, labia, and mammary glands. The male reproductive system contains the gonads (testes), epididymis, ductus deferens, penis, and scrotum - Function: Female gonads produce oocytes (the cells from which an egg develops) and also release hormones that regulate reproduction and development - Function: Male gonads produce sperm and release hormones that regulate reproduction and development - Fertilization is the combination of a sperm and an oocyte, resulting in the formation of a new life

Structural organization

o Intro: - Describing the anatomy and physiology of the human body according to the different hierarchical levels of its structural organizations can greatly assist in explaining its functions. - The 5 levels of organization help us to understand the anatomy and physiology of the body - Chemical à cellular à tissue à organ à system à organism (the body) - Each subsequent level becomes increasingly complex. However, all levels function through the interaction of their constituent parts. In other words, chemical reactions contribute to cell function, cellular interactions contribute to tissue function, and so on. o Chemical: - The chemical level is the most basic level of structural organization - The human body is made up of chemical elements called atoms. Oxygen, carbon, hydrogen, and nitrogen make up 96% of the body's mass. There are 22 other elements that also commonly occur in the human body, such as iron for example. - Atoms combine to form molecules, for example water, glucose, and DNA. The properties of different atoms, and therefore molecules, result in a wide array of chemical reactions, and this leads to a greater degree of complexity in the higher levels of structural organization. o Cellular: - There are many different types of cells found in the body, such as sperm cells or nerve cells. The sum of the chemical reactions in a cell makes up its structure and function. Often these reactions are confined to specific regions within a cell, known as organelles. These are made of molecules organized into special functional units. o Tissue: - There are four basic types of tissue grouped together by common features of structure and function: · epithelial · connective · muscular · nervous - The function of a tissue is influenced not only by its constituent cells, but also by the extracellular material and intercellular connections. o Organ: - An organ is a structure composed of two or more different types of tissue. Organs have specific functions and usually have recognizable shapes, such as the bean shape of a kidney. Organs found in the body include the heart, brain, stomach, skin and bones. o System: - Related organs working for a common function is what constitutes a system. The digestive, nervous, and cardiovascular systems are all examples of this - A single organ however, can be part of one or more systems. For example, the pancreas belongs to both the endocrine and digestive systems. some systems have organs that are in direct physical contact and thus function together, such as the organs of the digestive system, but others are related by functional or structural similarities and do not have direct contact, such as the glands that form the endocrine system.

Principles of homeostasis

o Intro: - Homeostasis is the existence and maintenance of relatively stable conditions inside the body despite the influence of dynamic and unpredictable internal and external environments. For example, even with fluctuations to the temperature of the external environment, the body maintains a relatively constant internal temperature of approximately 98.6℉ (37℃) o Homeostatic controls: - Homeostasis is achieved by the continuous interaction of the body's many regulatory processes. Maintaining homeostasis is a difficult task for the body as both the external and internal environments are under continuous disruption, causing imbalances within the body, which must be regulated in order for the body to function effectively as a whole. - The body functions within a narrow range of tolerance limits and maintains its internal environment by monitoring and regulating variables or controlled conditions such as temperature, salinity, ion concentration, oxygen levels, and pH. The normal value or range of values of a controlled condition are known as the set point and set point range respectively, with the upper and lower values of the set point range known as the normal limits. For homeostasis to be achieved, each controlled condition must be regulated to within the normal limits of the set point range. - Homeostasis is achieved principally by feedback systems in place throughout the body. These systems monitor and respond to changes in the condition of the body, such as blood glucose levels, temperature, or blood pressure.. - A negative feedback system reverses or negates any potential harmful change in a controlled condition, bringing it back to within the normal limits of its set point range, towards and ideal normal value - A positive feedback system reinforces or promotes any changes from a previous state, advancing the controlled condition to its optimal required state. o Feedback systems: - Feedback systems or loops involve both nervous and hormonal regulation and include the following components: -Stimulus: A stimulus is any disruption or change in a controlled condition or environment o Example: change in temperature, salinity, ion concentration, oxygen levels, or pH. - Receptor: A receptor is a sensor within the body that monitors the surrounding environment and responds to a stimulus by sending information, in the form of either a chemical or electrical signal, to a control center somewhere else within the body o Example: mechanoreceptor (sense mechanical force), chemoreceptors (sense change in chemical composition), thermoreceptors (sense change in temperature), and photoreceptors (sense change in light). - Control Center: A control center, also referred to as an integrating center, is a region of the brain that receives information about the stimulus from the receptor, determines the appropriate response and relays information about the response to the effector. It is the control center that determines the set point around which the controlled condition is maintained. o Example: Hypothalamus and pituitary gland - Effector: An effector is a structure within the body such as a cell, tissue, organ, or system that provides the means for carrying out the response o Example: Muscles, glands, and organs - Response: negative feedback: A response is elicited to counteract or negate the stimulus. Positive feedback: A response is elicited to promote the stimulus o Example: Dilation/constriction of blood vessels, sweating, shivering, milk ejection, change in breathing rate, increased/decreased muscle contraction, increased/decreased hormone secretion, and increase/decrease in heart rate. - Feedback: Negative feedback: if the response counteracts the stimulus, the response is halted. If the response is not strong enough to counteract the stimulus, the feedback loop begins again. negative feedback repeats until the controlled condition is brought back to within the normal limits of its set point range. o Positive feedback: the positive feedback repeats, often increasing deviation from the set point or ideal normal value, until the original stimulus is removed (external stimulus must stop the loop) - Negative feedback systems: o An example of a typical negative feedback system is thermoregulation o Thermoregulation is the body's homeostatic mechanism for keeping body temperature within the normal limits of its set point range, with the set point being normal or optimal body temperature (98.6℉). A change in body temperature may be triggered by a number of factors including a change in the temperature of the external environment and an change in the metabolic activity of cells within the body o Stimulus: An increase in body temperature to above the set point or normal of 98.6℉ o Receptor: peripheral thermoreceptors in the skin detect the increase in body temperature. o Control center: information in the form of electrical signals (nerve impulses) is sent from peripheral thermoreceptors to a region in the brain called the hypothalamus o Effector: information is relayed from the hypothalamus to blood vesselsaround the body and sweat glands in the skin o Response: Blood vessels respond with vasodilation to increase heat loss, while the sweat glands respond by secreting sweat to increase heat loss. Vasodilation and sweating lead to a drop in body temperature. o Feedback: the cooling then negates the original stimulus and reduces the response, in a negative feedback loop. - Positive feedback systems: o An example of a typical positive feedback system is lactation. o Lactation is regulated y a homeostatic mechanism through which milk ejection is stimulated by a suckling child. Milk ejection intensifies and increases through positive feedback until the child stops suckling. o Stimulus: Mechanical stimulation of the nipple by a suckling child o Receptor: Peripheral mechanoreceptors in the nipple detect a child sucking o Control center: Information in the form of electrical signals (nervous impulses) is sent from peripheral mechanoreceptors to a region in the brain called the hypothalamus, which in turn relays information in the form of chemical signals (hormones) to an endocrine organ in the brain called the posterior pituitary o Effector: The hormone oxytocin is released from the posterior pituitary gland and acts as a chemical signal, stimulating the effector cells surrounding the milk-producing glands of the breast. o Response: cells surrounding the milk-producing glands of the breast contract, triggering milk ejection o Feedback: The milk production then reinforces the original stimulus and promotes the original milk ejection response, in a positive feedback loop, until the stimulus is removed (the child stops suckling) - Homeostatic imbalance: o A disturbance in homeostasis outside the narrow boundaries usually controllable by feedback systems most often results in disease, or in severe cases, death o Disease results from uncontrollable disruptions to homeostasis, which leave regions or systems within the body unable to sustain a normal degree of function. This abnormal functioning results in a recognizable set of sings and symptoms attributable to a specific condition or disease. o In more severe cases, where numerous disruptions to homeostasis occur simultaneously, negative feedback systems are overwhelmed and positive feedback systems operate at potentially harmful levels, leaving the body weak, vulnerable, and susceptible to death.

introduction: chemistry

o Introduction: - The most basic level of organization found in the body is at the chemical level. The term matter is used to describe objects that occupy space and have a discernible mass. All cells, tissues, and organs in the body are comprised of matter, which is arranged in small organizational units known as atoms. Matter exists in three major states: solid, liquid, and gas. A change in state occurs when matter transforms from one state to another. When matter moves from a solid to liquid (melting), or from liquid to gas (evaporation/boiling), energy is absorbed in the form of heat. When matter moves in the opposite direction, from gas to liquid (condensation), and liquid to solid (freezing), energy is released in the form of heat. o Solids: - Solids have atoms arranged in fixed positions with definite shape and volume. Of the three states of matter, solids have the least amount of kinetic energy as the strong intermolecular forces between the atoms prevents them from moving freely and instead they vibrate constantly.Examples of solids include bone. o Liquids - Liquids have a constant volume but do not take a definite shape. Instead, they assume the shape of their container. Liquids have more kinetic energy than solids as the intermolecular forces between the atoms are weaker allowing them space for limited movement within the confines of their container.Examples of liquids include blood plasma and water. o Gases: - Gases do not have a definite shape or volume. Of the three states of matter, gases contain the highest amount of kinetic energy. This is because the intermolecular forces between atoms are much weaker and, therefore, the space between gaseous molecules is large allowing them to move freely.Examples of gases include oxygen and nitrogen.

Introduction

o Metabolism: Biochemical reactions that occur within the body, divided into two phases; catabolism and anabolism - Catabolism: Chemical reactions that break down complex substances into simpler substances - Anabolism: Chemical reactions that build up simple substances into complex substances - Features: An important aspect of many of the complex reactions that occur within the body. Digestion for example, involves catabolic and anabolic reactions, which enable different molecules to be absorbed, broken down, and re-synthesized. o Excretion: Removal of the waste byproducts of metabolic reactions - Features: excretion is of great importance as it prevents substances from reaching toxic levels in the body. For example, cells respire in order to release energy, but in doing so produce carbon dioxide. To avoid a buildup of this byproduct in the body, it is excreted when breathing out. - Responsiveness/regulation: the ability of the human body to detect changes in the environment and make any appropriate responses - Features: Responsiveness is important to ensure survival. For example, the nervous system can detect tissue damage such as when you burn your finger on a hot iron and initiate the appropriate response, e.g. withdrawal of the hand. o Movement: A change in position or location (can occur at all levels of structural organization) - Features: Movement of certain substances or cells around the body at key points in time is crucial for the correct functioning of many of the systems of the body, e.g. the heart pumps blood around the body. - Growth: An increase in body size due to cell development and differentiation - Features: Growth is an essential requirement for the development of the various cells and tissues making up the organs and systems of the body o Differentiation: The process by which an unspecialized cell becomes specialized - Features: Each cell in the body has a different structure to that of its precursor cell. For example, red blood cells and some white blood cells arise from the same type of cell in the bone marrow. o Reproduction: refers to the formation of new cells within an individual in order to repair, replace, or grow new tissue. It can also refer to the fertilization of an egg by a sperm at the beginning of a new life - Features: creation of new life and maintenance of existing tissues and cells within the body.

Plasma membrane

o Plasma membrane - The plasma membrane is a flexible membrane that surrounds all cells, forming a barrier between the intracellular fluid (inside the cell), and extracellular fluid (outside the cell). The main structural framework of the plasma membrane is the lipid bilayer, a thin membrane made of two layers of phospholipid molecules. - Phospholipid molecules are said to be amphipathicbecause they have dual polarity. They are made up of a polar phosphate-containing head, and two non-polar fatty acid tails.The polar head is hydrophilic, meaning it is attracted to water, and the non-polar tails are hydrophobic, meaning they repel water.When they are exposed to water, phospholipid molecules arrange themselves into an enclosed double-layered sheet, with the hydrophilic heads facing the water-rich environment, and the hydrophobic tails facing each other in the center. - The plasma membrane is not a fixed, rigid structure. Instead, it is in a continuous state of movement because the lipid molecules are free to sway, rotate, and move laterally within the bilayer. This gives it fluidity. The fluidity of the plasma membrane is dependent on two factors: the composition of lipids in the bilayer, and the amount of cholesterol present. Phospholipids can be made from saturated or unsaturated fatty acids. Phospholipids with straight, saturated fatty acid tails align more closely and so reduce fluidity. Those containing unsaturated fatty acids are prevented from moving too closely together by the kink formed by the double-carbon bond, and so increase fluidity. - Cholesterol molecules are embedded within the phospholipid bilayer and provide structural stability. When temperatures are high, the cholesterol holds the phospholipids together, preventing the membrane from becoming too fluid, and when temperatures are low, the cholesterol prevents them packing too closely together, retaining fluidity. The fluidity of the membrane is vital for providing structural support to the cell, and permitting movement. - Membrane fluidity also allows the insertion of membrane proteins within the lipid bilayer. Membrane proteins can be classed as peripheralor integral. Peripheral proteins sit on the inner or outer surface of the plasma membrane, attached to the polar heads of the phospholipids. Most are glycoproteins, with their carbohydrate portions forming a sugary outer coat called the glycocalyx, which functions in cell recognition and adhesion. Integral proteins span the whole plasma membrane, and are firmly anchored between the fatty acid tails. They are key to another property of the plasma membrane: its permeability. - The plasma membrane allows certain substances to move more readily than others, into and out of the cell. Small molecules such as carbon dioxide and oxygen are able to to passively diffuse across the plasma membrane unaided, because they have no charge. Ions and large uncharged polar molecules such as glucose, sodium, and potassium ions are unable to cross the membrane as they have a charge, or are too large. The transport of these molecules is facilitated by integral proteins such as selective ion channel proteins, carrier proteins, and receptor proteins, which can be passive, or active, depending on whether they require cellular energy. This selective permeability allows the plasma membrane to regulate what enters and exits the cell. - A structural model, known as the fluid mosaic model, is used to describe the plasma membrane. According to this model, the constantly moving, fluid lipid bilayer contains many embedded membrane proteins dispersed in a mosaic arrangement. o Structures of the plasma membrane - The plasma membrane is composed of a number of different biological molecules, although most abundant are proteins and lipids.The table below describes the main types of molecules found within the membrane in more detail. § Lipid bilayer: - Phospholipid: - The most abundant lipid in the plasma membrane. Phospholipid molecules are said to be amphipathicbecause they have dual polarity. They are made up of a polar phosphate-containing head, and two non-polar fatty acid tails. The polar head is hydrophilic, meaning it is attracted to water, and the non-polar tails are hydrophobic, meaning they repel water. When they are exposed to water, phospholipid molecules arrange themselves into an enclosed double-layered sheet, with the hydrophilic heads facing the water-rich environment, and the hydrophobic tails facing each other in the center. - Cholesterol: - Cholesterol molecules are embedded within the lipid bilayer and provide structural stability. When temperatures are high, the cholesterol holds the phospholipids together, preventing the membrane from becoming too fluid, and when temperatures are low, the cholesterol prevents the phospholipids packing too closely together, retaining fluidity.Cholesterol is also mildly amphipathic. It consists of a polar OH group, that forms hydrogen bonds with the phospholipid heads, and non-polar steroid rings and hydrocarbon tails that sit between the fatty acid tails. - Glycolipids - Glycolipids are peripheral lipids that only sit on the outer surface of the plasma membrane. They have polar carbohydrate heads that nestle among the phospholipid heads and non-polar fatty acid tails that are arranged between the fatty acid tails. o Membrane proteins: § Channel proteins: - Channel proteins are a type of transmembrane, or integral protein. They have a central channel extending from the extracellular side to the cytoplasmic side of the plasma membrane. - Function: - They allow the flow of specific ions from one side of the plasma membrane to the other. Ion channels may be selective for one type of ion or they may be common, allowing several different ions to pass through. They can also permit the movement of water. - Examples: - Sodium ion channels and potassium ion channels. § Carrier/transporter proteins - Carrier/transporter proteins are a type of transmembrane, or integral protein that are capable of a conformational (structural) change. Carrier/transport proteins may require energy in the form of adenosine triphosphate. - Function: - They transport specific substances across the plasma membrane from one side to the other. - Examples: - Glucose carrier proteins. § Receptor proteins - Receptor proteins are a type of transmembrane, or integral protein. They have binding sites for a specific molecule. - Function: - They recognize and bind to specific molecules, known as ligands, leading to an alteration in cellular function. - Examples: - Epinephrine receptors, G protein-coupled receptor. § Enzymes - Enzymes may exist as transmembrane, or integral proteins, embedded into the plasma membrane, with an active site facing either inside or outside the cell. - FUNCTION: - The active site catalyzes specific chemical reactions either inside or outside the cell. - Examples: - Adenylate cyclase and carbonic anhydrase. § Cell adhesion molecules - Cell adhesion molecules may be either integral or peripheral, with anchorage sites for connecting filaments to the plasma membrane. - Function: - They provide structural support and stability to a cell. They may also adhere two adjacent cells to each other, or help with movement of the cell. - Examples: - Desmosomes. § Cell identity markers - Cell identity markers may be glycoproteins or glycolipids. They extend from the plasma membrane and consist of specific combinations of cell surface proteins, that are characteristic of a particular cell type. - Function: - They enable a cell to be recognized and distinguished from other cells. They also enable recognition of foreign cells. - Examples: - Major histocompatibility proteins and blood type markers.

protein synthesis and DNA replication

o Protein synthesis and DNA replication § Within a cell, the genetic material of an organism is packaged within the nucleus in long structures called chromosomes.A chromosome contains double-stranded molecules, known as DNA, which have a double-helix shape . § Each of the strands of a DNA molecule are made up of small repeating units called nucleotides. Each nucleotide has three parts: a phosphate group, a sugar called deoxyribose, and one of four different nitrogenous bases. These bases are called adenine, guanine,cytosine, and thymine. § The bases of each strand align along the center of the double helix, and bind to each other by hydrogen bonds. Only certain pairs of bases will bond with each other: adenine will only bond with thymine, and guanine will only bond with cytosine. The sequence of these four bases on the strands of DNA represent the genetic information within the cell.These sequences serve as templates, directing the cell to make proteins; the order of bases determining the type of protein produced. § Protein synthesis occurs in two stages: transcription and translation. During transcription, specific enzymes within the nucleus 'read' the sequence of bases in the DNA template to produce an intermediate molecule called messenger RNA (mRNA), which has a complementary structure to the template. During translation, this mRNA molecule binds to a ribosome, and is read by other enzymes to produce a protein. § DNA is also important in cell division. When a cell divides, it must duplicate all of its DNA. It does this by separating the two strands of the existing DNA molecules. Enzymes then use each strand as a template to produce two complete sets of each DNA molecule. This is called DNA replication. o Protein synthesis: § Proteins are coded from strands of DNA. The sequence of amino acids in a protein is determined by the order of nucleotides in the DNA strand. Sections of DNA responsible for producing proteins are known as genes, and the sequence of nitrogenous bases are referred to as the genetic code. The genetic code consists of three nitrogenous bases, known as codons, where each codon is specific to a single amino acid. The production of a protein takes place in two main steps: transcription, which occurs in the nucleus and translation, which is carried out in ribosomes both free in the cytosol, and bound to the nuclear envelope and rough endoplasmic reticulum.For more information on the structure of DNA and RNA, see 'Chemistry: Nucleic Acids'. o Transcription § During transcription, DNA is used as a template to generate complementary sequences. These sequences are then used in the process of translation. Transcription occurs in the nucleus of the cell. § The enzyme RNA polymerase binds a DNA template at a special nucleotide sequence near the beginning of a gene, called a promotor. This is where transcription begins. § RNA polymerase unwinds a small section of the double helix. Free RNA nucleotides within the nucleus align with, and bind to, bases of the template DNA strand, forming complementary base pairs § RNA polymerase detaches from the DNA template and the newly transcribed RNA molecule at a special nucleotide sequence at the end of a gene, known as the terminator. This is where transcription ends. o RNA processing § DNA is made up of two regions of nucleotides: introns and exons. Introns are non-informational regions that do not code for proteins, and exons are informational regions that do code for proteins. During transcription, when a messenger RNA (mRNA) is produced, both introns and exons are copied. Before immature mRNA (or pre-mRNA) can be used in translation to direct protein synthesis, it must undergo a process known as RNA splicing, to remove the non-coding introns. During this process, enzymes known as small nuclear ribonucleoproteins (snRNPs) cut out the introns, and join together the exons, resulting in a functional mRNA molecule that contains only protein coding regions. Once all of the introns have been removed, the mature mRNA molecule can then leave the nucleus via the nuclear pore to reach the cytoplasm, where translation can take place. o Translation § Once the mRNA molecule leaves the nucleus via a nuclear pore, it binds to a binding site on the small subunit of a ribosome. The mRNA is then used as a template for transfer RNA, tRNA, molecules to form amino acid chains. Translation occurs on ribosomes in the cytosol of a cell.The small subunit of each ribosome has a binding site for mRNA.The large subunit of each ribosome has three binding sites for tRNA: § A: for tRNA that delivers the amino acid. § E: for tRNA that inserts the amino acid into the chain. § P: for tRNA that holds the growing polypeptide chain. § tRNA molecules have a nucleotide sequence known as an as an anticodon at one end, and a single amino acid at the other. A specific tRNA anticodon (UAC), known as the initiator tRNA, binds to a specific sequence of mRNA bases known as the start codon (AUG).This is where translation begins. § The small ribosomal subunit joins with a large ribosomal subunit which displays A, E, and P sites. The initiator tRNA binds to the P site. A new tRNA molecule, bearing anticodons and an amino acid, binds to the A site, recognizing and pairing up with complementary base sequences of the bound mRNA molecule. § A peptide bond is formed between the amino acids of the initiator tRNA and the amino acid of the tRNA at site A, leaving the polypeptide chain on the latter. The polypeptidyl-tRNA is relocated to the P site and the initiator tRNA is ejected at the E site. An enzymic region of the large ribosomal subunit catalyzes the formation of the peptide bonds between these amino acids.As complementary base pairs are continually formed, and tRNA molecules progress along the ribosomal binding sites, the polypeptide chain grows, ultimately forming a protein. § Newly synthesized proteins undergo post-transitional modification in the rough endoplasmic reticulum and Golgi complex. During this process, the physical and chemical properties of a protein are defined as they are folded, stabilized, sorted, and packaged into vesicles to be transported to their target cell, organ, or region within the body. o DNA replication: § Within a cell, the genetic material of an organism is packaged within the nucleus in long structures called chromosomes. Each chromosome contains double-stranded molecules, known as DNA, which have a double-helix shape. Before a cell can divide, it must replicate all of its DNA, producing two identical copies. This process is called DNA replication. § DNA replication begins when the enzyme helicaseunwinds the double-helix structure, separating it into two strands. The Y-shaped region that is formed is called the replication fork, and each branch is made up of a single strand of DNA. DNA strands have two different ends, the 5 prime (5') end, and the 3 prime (3') end, which show 'directionality'. The two strands that make up a double helix run in opposite directions to each other. The 5' to 3' strand is known as the leading strand, and the 3' to 5' strand is known as the lagging strand. This orientation determines the direction in which DNA replication will occur. § When the double helix is unwound, each strand has exposed nitrogenous bases that form a template from which the new DNA will be synthesized. Synthesis of a new strand of DNA on the leading strand requires a primase enzyme to lay down an RNA primer, a short sequence of complementary RNA nucleotides that pair with the leading-strand template. This primer is required because the major enzyme of DNA replication, DNA polymerase, cannot initiate synthesis of a strand of DNA directly from the leading strand alone. With the primer in place, DNA polymerase is recruited to the RNA and DNA strands and replication begins. § DNA polymerase extends the new strand of DNA from the RNA primer, reading the leading-strand template, and adding complementary free DNA nucleotides to the 3' end of the newly synthesized strand. These nucleotides have bases which are complementary to those of the leading-strand template: adenine bases bind to thymine bases, and cytosine bases bind to guanine bases. The DNA polymerase moves continuously along the leading-strand template, synthesizing the new strand in a 5'-3' direction, until replication is complete. A repair polymerase then replaces the RNA primer with DNA nucleotides. § Because the lagging-strand template is oriented with its 3' end towards the replication fork, synthesis of a new strand of DNA cannot occur continuously. This is because DNA polymerase can only add nucleotides to the 3' end of a DNA molecule. As with the leading strand, a primase enzyme must lay down an RNA primer, which acts as a marker, signaling where DNA polymerase should be recruited.The RNA primers are assembled in a 5'-3' direction in short segments. § DNA polymerase constructs the new strand from the primer, reading the lagging-strand template, and adding free DNA nucleotides to the 3' end of the newly synthesized strand, until it reaches a previously assembled primer. These short strands of DNA are known as Okazaki fragments. These processes occur multiple times as the DNA is unwound, resulting in short segments of DNA, the Okazaki fragments interspersed with RNA primers § A repair polymerase then replaces the RNA primers with DNA nucleotides, which are then linked to the fragments by an enzyme known asDNA ligase. The end product of DNA replication is two double-stranded DNA molecules, both identical to the original one.

Proteins

o Proteins: - Chemical reactions in the body and cellular activities all depend on the interaction of a variety of dynamic molecules called proteins. Proteins are a large group of organic compounds formed of hydrogen, carbon, nitrogen, oxygen, and often sulfur atoms. They are built from small units called amino acids, which join together to form long chains. In turn, these chains fold into unique 3 dimensional structures, which are involved in almost every aspect of the functioning of the body.Proteins account for approximately 20% of our body mass. They are commonly consumed in our diet from animal sources such as meat, fish, milk, and eggs, as well as plant sources such as cereal, fruits, nuts, and seeds. - All protein molecules are made of amino acids. Each amino acid consists of a hydrogen group, amine group, carboxyl group, and a variable R group. The R group varies among each of the 20 types of amino acid, making each of them chemically unique. Amino acids can be classified as non-essential, able to be synthesized from components found in the body, or essential, which cannot be synthesized. Essential amino acids must therefore, be obtained from food as proteins. - Ingested proteins are broken down in the stomach into amino acids by enzymes called proteases. These amino acids can be used for energy, or recycled in the synthesis of new proteins. Amino acids combine in a unique sequence to form a chain called a polypeptide. - Small proteins can be made of a short chain of amino acids; however, the large proteins may consist of more than one polypeptide chain folded together. Each variation in amino acid sequence can produce a different protein, which has a specific function within the body. - There are many different types of protein, classified according to their function. These include enzymes, and structural,contractile, immunological, and regulatoryproteins. Enzymes such as lipase act as catalysts to speed up the rate of chemical reactions in the body. Structural proteins such as keratin, found in hair and nails, provide a framework to give support to cellular structures. Contractile proteins such as actin and myosin contract and relax muscle fibers to produce movement. Immunological proteins such as antibodies protect the body against infections from pathogens and foreign substances, and regulatory proteins, such as the hormone, insulin are chemical messengers that regulate homeostasis in the body. § Proteins are one of the most diverse groups of organic compounds. They are involved in almost every physiological process in the body, from initiating movement to providing structural support. o Structure of proteins - The structure of a protein determines its use in the body. Proteins exist in many shapes, sizes, and forms; however, all proteins are comprised of simple monomeric units called amino acids. Combined into larger units called polypeptides, amino acids are further organized into complex arrangements to produce a protein.Proteins are synthesized by cells through the processes of transcription and translation. The breakdown and synthesis of proteins forms the foundation of many of the cellular activities that take place in the body. The structure of proteins and their ability to breakdown and be re-synthesized from amino acids is, therefore, vital to the successful functioning of the body. For more information on protein synthesis, see 'Cell Biology'. o Amino acids: - Amino acids are the fundamental units and building blocks of all proteins. In the body, 20 different types of amino acid can be found.All amino acids have a similar structure that consists of a central alpha carbon atom that has four other entities covalently bonded to it: a hydrogen atom, an amine group, a carboxyl group, and an R group. o Hydrogen atom: - The hydrogen group consists of a single hydrogen atom covalently linked to the alpha carbon atom. It can form hydrogen bonds with atoms from other amino acids. o Amine group - The amine group (-NH2) consists of a nitrogen atom and two hydrogen atoms covalently linked to the alpha carbon atom. The amine group enables the amino acid to act as a base in strongly acidic environments, by accepting a hydrogen ion to become -NH3+. o Carboxyl group - The carboxyl group (-COOH) consists of a carbon atom with oxygen double-bonded to it, and a hydroxyl group (an oxygen and hydrogen together) bonded to the carbon. The carboxyl group enables the amino acid to act as an acid in strongly alkaline environments, by donating a hydrogen ion to become -COO-. o R group - The R group varies in the 20 amino acids, making each of them chemically unique. The composition of an R group of amino acids is mostly that of a simple hydrocarbon chain. The simplest R group is that of the amino acid glycine, as it is simply a hydrogen atom. Other amino acids have more complex groups making them either hydrophobic or hydrophilic. In addition, some amino acids' R groups include less common atoms, such as the thiol group (SH) seen on the amino acid serine. The exact composition of each R group determines the possible interactions of that amino acid. o Polypeptides - Amino acids can join together to form larger molecules called polypeptides. Polypeptides are long chains of amino acids covalently linked to one another by peptide bonds. A peptide bond is formed between the carbon atom of the carboxyl group of one amino acid and the nitrogen atom of the amine group of another. For every peptide bond formed, one molecule of water is released. Simple structures consisting of only two or three amino acids linked together by peptide bonds are called di- and tri-peptides, respectively.A polypeptide consists of a long, single chain of amino acids linked to each other by their amine and carboxyl terminals, to form a polypeptide backbone. The R groups of these amino acids do not participate in the peptide links so project sideways from the polypeptide backbone. o Proteins and levels of structural organization - Proteins can be simple or complex structures, depending on their polypeptide amino acid sequence (or primary structure) and the polarity of the R groups in their amino acid side chains. Proteins can contain one or more polypeptides and can, therefore, take on different levels of structural complexity through the binding and interaction of the amino acid side chains, as well as that of the groups of the polypeptide backbones. When proteins form more complex structures, they usually fold and bond in the following characteristic stages or levels: primary,secondary, tertiary, and quaternary(although not all proteins form a quaternary structure). - Primary structure: - The primary structure of a protein is the specific sequence of amino acids joined by peptide bonds to form a polypeptide. Each protein has a different primary structure, making it unique. - Secondary structure: - The secondary structure of a protein is described as the backbone of the protein and the conformational shape it takes when the non-R groups of the amino acid react and bond with one another. Secondary protein structures usually manifest as loose coils of polypeptides, called alpha helices or beta-pleated sheets. - Alpha helix: - An alpha helix is formed by the twisting of a polypeptide chain into a right-handed helix, which appears to be turning in a clockwise direction. This structure is formed and held in place by peptide bonds that form between the aligned amino acids sitting above one another. These bonds make the alpha helix a strong and stable structure that acts as a solid, rod-like cylinder, providing mechanical support to the protein. - Beta pleated sheets - A beta-pleated sheet is formed when the carboxyl and amine groups of the polypeptide backbone form hydrogen bonds with one another. This also forms a stable structure whereby the polypeptide chains lie in parallel lines next to one another, forming a sheet. The pleats are created by the carboxyl or amine groups forming bonds with the neighboring (rather than opposing) groups and then folding back on themselves. - Tertiary structure: - The tertiary structure of a protein is the 3D structure that a protein takes when the secondary structures of polypeptides interact and fold in on themselves. This structure is held together by numerous bond types. When two cysteine amino acids come into close proximity, the sulfur R groups bond with each other to form a disulfide bridge. As well as the usual covalent bridges, there are other bonds, namely hydrogen and ionic bonds, that play a role in determining the protein shape. Because most proteins exist in an aqueous solution, the hydrophilic amino acids of the protein end up on the surface of the protein, whereas the hydrophobic regions squeeze into the inside of the protein in order to avoid the water. This arrangement plays a significant role in determining the conformation (shape) of the protein. - Quaternary structure - The quaternary structure of a protein is the most complex conformation a protein can take. Not all proteins have this level of structure, however, when two or more polypeptide chains (folded into a tertiary structure) come into close contact, they bond together to form a quaternary protein structure. Quaternary structures are held together by similar bonds to that of tertiary protein structures. Proteins fold into quaternary structures due to the requirements for them to become a particular shape. For example, enzymes need to have an active site that is complementary to the substrate they catalyze in order to work. o Functional classification of proteins - Proteins are one of the most versatile sets of molecules found in the body. Each protein is made up of a chain of amino acids of varying length. It is the specific combination of these 20 different amino acids in the chain that determine the structure and function of a protein. A singe change in one amino acid may drastically alter the functional properties of that protein. As a result, there are thousands of combinations.This sequence can also determine the shape in which proteins form. Longer peptide chains can fold into quaternary structures, becoming globular proteins, such as enzymes, or fibrous proteins, such as the structural protein keratin. It is possible to classify proteins into key groups based on their function: - Enzymes: - Enzymes such as lipase act as catalysts to speed up the rate of chemical reactions in the body.For more information on how enzymes function, see 'Enzymes' below. - Function: o Speed up chemical reactions in the body. - Structural: - Structural proteins, such as keratin and collagen, exist in the body to provide a framework, giving support to cellular structures. - Function: - Structural framework of the body. - Contractile - Contractile proteins, such as actin and myosin, work together to produce movement of muscle fibers by contracting and relaxing them. - Function: - Contraction of muscle fibers to produce movement. - Immunological - Immunological proteins, such as antibodies and interferons, work as part of the immune response to protect the body against infectious pathogens and foreign substances. - Function: - Protect the body from infection - Regulatory - Regulatory proteins, such as the peptide hormones insulin,prolactin, neurotransmitters, and ADH, govern and regulate several processes in the body. Hormones classed as peptides, e.g., insulin, are constructed from short chains of amino acids. They play a key role in the maintenance of homeostasis by regulating the activity of muscle cells, controlling glandular secretions, altering metabolism, and promoting growth and development. - Function: - Regulate physiological processes in the body. - Transport: - Transport proteins, such as hemoglobin, albumin, and the sodium-potassium pump, move substances around the body via transport mediums, such as the blood. Transport proteins present in the plasma membrane also play a key role in maintaining the ionic composition of bodily fluids. - Function: - Move substances around the body, and maintain homeostasis of bodily fluids. - Enzymes: - An important class of protein is enzymes,without which many of the metabolic activities that take place in cells would not occur.Enzymes are globular proteins that act as catalysts. Like all catalysts, enzymes work by dramatically increasing the rate of a reaction and may affect catabolic or anabolic reactions. On their own, most enzymes are catalytically inactive and are known as apoenzymes. Many require the binding of an additional non-protein 'helper molecule', such as an organic coenzyme or an inorganic cofactor to become catalytically active. Once active, the resulting complex is known as a holoenzyme and is ready to interact with a substrate, the molecule or molecules that the enzyme acts upon. Enzymes are very specific about which substrates they interact with. The substrate or substrates must fit the active site of the enzyme, almost like a key fits a lock. This high level of specificity means generally an enzyme is only able to catalyse one chemical reaction. During catabolic reactions once the substrate is bound to the enzyme, the enzyme alters shape, applying physical pressures to the substrate, converting it into smaller molecules, called products. When this reaction is complete, the enzyme is able to bond with another substrate and the reaction is repeated. During anabolic reactions enzymes combine substrates together to make a larger product. - Apoenzyme - The apoenzyme is the protein section of an enzyme. Without the cofactor or coenzyme, this part of the enzyme is catalytically inactive. o Coenzyme: - Coenzymes are non-protein organic molecules, usually vitamin derivatives, that must bind to the enzyme to activate it. o Cofactor: - Cofactors are inorganic ions or molecules that must bind to the enzyme to activate it, in a similar manner to coenzymes. o Active site: - The active site of an enzyme is an area present on the surface of the protein that is complementary to the shape of the substrate. The substrate is the molecule or substance that the enzyme acts upon. The chemical reaction can only proceed once the substrate has bound itself to the enzyme's active site, either by an exact 'lock and key' method, or by the enzyme altering its shape slightly to accommodate the substrate. For this to happen, the enzyme has to 'recognize' the substrate and test whether or not its active site is complementary to it.

levels of organization: from smallest to largest

· Subatomic particles - electrons, protons and neutrons · Atom - similar to element (smallest unit) · Molecule - two or more atoms joined together · Organelle - large molecules forming compartmentalized structures in cells · Cell - smallest unit of life · Tissue - types of cells having similar function; epithelium (line exterior and interior spaces), muscle (contractive function), nervous (signal conduction) and connective tissue (fills in between the other tissues) · Organ - formed from other tissue types · System - organs having similar function · Multicellular Organism - dicrete unit of macro-life · Population - group of similar organisms (same species) · Community - all species living in a certain area · Ecosystem - a community and its physical environment (lake, ocean, desert) · Biosphere - all places on earth which support life

Which movement about a synovial joint describes the moving the arm or leg away from the body? 1. abduction 2. adduction 3. retraction 4. supination 5. pronation 6. protraction

1. abduction

Is the ulna on the medial or lateral side of the forearm when the arm is in the anatomic position? 1. lateral 2. medial

2. medial

Which one of the following types of cell is responsible for the initiation of the calcification process in bone? 1. osteogenic cell 2. osteoblast 3. osteocyte 4. osteoclast

2. osteoblast

Which one of the following terms best describes the dense layer of connective tissue that surrounds the cartilage of a developing bone? 1. diaphysis 2. perichondrium 3. osteoid 4. endosperm

2. perichondrium

Which bone below forms the lower jaw. 1. hyoid 2. zygomatic 3. mandible 4. maxilla 5. nasal 6. lacrimal 7. palatine

3, mandible

In movements possible around a synovial joint, __________ describes the movement of an arm or leg being moved away from the body. 1. circumduction 2. adduction 3. extension 4. abduction 5. flexion 6. hyperextension

4. abduction

which vertebral type does not posses a vertebral body? 1. first lumbar 2. T1- first thoracic 3. T2 - second thoracic 4. C2- second cervical 5. C1- first cervical 6. sacrum

5. C1- first cervical

Hypothalamus and Pituitary Gland

The hypothalamus and pituitary gland work together as a functional unit called the hypothalmic-pituitary axis. Seven body hormones are secreted through this connection and help regulate growth, development, metabolism and homeostasis. This the primary link between the nervous system and the endocrine system. Hypothalamus The hypothalamus is located just below the thalamus and above the brainstem and is the size of an almond. Two main types of nuclei are involved in the functioning of the hypothalmic-pituitary axis and they are named the paraventricular nucleus (PVN) and supraoptic nuclei. The PVN secrete oxytocin and antdiuretic hormone at the axon terminals in the posterior pituitary and the medial region of the PVN secretes releasing and inhibitory hormones that control the release of anterior pituitary hormones. Another set of nuclei called the Supraoptic nucleus of SON are located over the optic chiasma (where the optic nerves cross over each other) and secrete antidiuretic hormone (ADH) down their axons to eventually be secreted by the posterior pituitary. The pituitary Gland also called the hypophysis is a small endocrine gland attached to the floor of the brain by a small stalk named the infundibulum. It is protected as it rests in a depression found in the upper surface of the sphenoid bone called the sella turcica (Turkish saddle) or hypophyseal fossa. The pituitary gland has two major subdivisions. adenohypophysis - anterior portion of pituitary (soley endocrine in function) neurohypophysis - posterior portion of pituitary (also has nervous function in addition to endocrine) During development, adenohypophysis arises from epithelial tissue forming roof of mouth and neurohypophysis is formed from nervous tissue. Adenohypophysis (anterior pituitary gland) The largest portion of adenohypophysis is the pars distalis. The pars distalis is composed mostly of glandular cells arranged in cords or clumps, which are intimately related to a vast system of sinusoids that meander between the cell clumps and cords. Hormones of Anterior Pituitary Gland Five different types of endocrine glandular epithelial cells found in adenohypohysis and they secrete seven different hormones. Thyrotrophs: basophilic (stain with basic dyes) synthesize and secrete thyroid-stimulating hormone (TSH) which targets the thyroid for the secretion of triiodothyronine (T3) and thyroxine (T4). Corticotrophs: basophilic staining, synthesize and secrete adrenocorticotropin hormone (ACTH) to target the suprarenal cortex in secretion of glucocorticoid hormones. Also secretes melanocyte-stimulating hormone (MSH), the function of which is not clear in humans. Somatotrophs: acidophilic (stain with acid dyes), synthesize and secrete Growth Hormone (hGH or somatotropin) which stimulates secretion of insulin-like factors (iGFs) which regulate protein, lipid and carbohydrate metabolism in many body organs and tissue. Lactotrophs: acidophilic, synthesize prolactin (PRL) which targets mammary glands stimulating milk production and secretion. Gonadotrophs: basophilic, secrete follicle-stimulating hormone (FSH) which targets gonads to stimulate monthly development of ovarian follicles and stimulates estrogen secretion from follicular cells. Also secretes luteinizing hormone (LH) which in the ovaries, trigger ovulation and the formation of the corpus luteum for secretion of progesterone which stimulates breasts for milk production. In the testes, LH stimulates secretion of testosterone. Neurohypophysis or Posterior Pituitary Gland Neurohypophysis is composed of pituicytes and terminal portions of axons of neurosecretory cells. The bulk of neurohypophysis is made up of many unmyelinated nerve fibers which make up what is called the hypothalamo-hypophyseal tract. The nerve cell body resides within the hypothalamus and their fibers extend down into neurohypophysis ending there. Throughout the neurohypophysis are found round structures of varying size called Herring bodies. Herring bodies are accumulations of neurosecretory material present in axoplasm of the fibers of the hypothalamo-hypophyseal tract. Oxytocin and antidiuretic hormone (vasopressin) are produced by the neurohypophysis. Terminal endings of these neurosecretory cells abut closely to the capillary network in the neurohypophysis and the capillaries are of the fenestrated type (contain holes in their walls) that are typical for capillaries found in endocrine glands. Hypophysioportal circulation is a second example of a portal system in the human circulatory system. The hepatic portal system is the other. This is an important connection from the hypothalamus which stimulates either the release or inhibition of hormones by innervation in the adenohypophysis. One portal system brings releasing or inhibiting factors to hormone-producing cells in adenohypophysis. Hormones released from nerve fibers into neurohypophysis from hypothalamus enter the capillary bed fed by an inferior hypophyseal artery and leave by way of a hypophyseal vein. The importance of this portal system is that it links the nervous system to the endocrine system. Control of Anterior Pituitary Gland Secretion of hormones from the anterior pituitary gland is controlled by regulatory hormones known as releasing hormones and release-inhibiting hormones which arise from the parvocellular neurons of the hypothalamus which then travel to the anterior pituitary via the blood stream. Control of Posterior Pituitary Gland The posterior pituitary does not synthesize any hormones but rather serves as a repository for the hormones oxytocin and antidiuretic hormone which are synthesized in the hypothalamus and then carried by nerve axons to the posterior pituitary for storage until released.

Lipids

o Lipids: - Lipids are a group of organic compounds formed by the elements carbon, hydrogen, and oxygen. They are hydrophobic molecules and are, therefore, not soluble in water.Lipids account for approximately 18-25% of our body mass. They are commonly consumed in our diet in a variety of food such as fats, oils, sterols, and phospholipids. Within the body, lipids play a central role as energy storage molecules, they form the main structural component of cell membranes, and function as messengers and signaling molecules. There are four main classes of lipids: fatty acids, triglycerides, phospholipids, and steroids. - Fatty acids are the simplest form of lipid in the body, and act as building blocks for the more complex lipids. Fatty acids can be saturated or unsaturated. In saturated fats, each carbon in the chain is connected to at least two hydrogen atoms; thus, the carbon chain is 'saturated' with hydrogen atoms. In unsaturated fats, there are one or more double bonds between the carbon atoms. As a result, hydrogen atoms are lost and the carbon chain becomes unsaturated. - Both types of fatty acids are an important source of fuel. However, a diet high in saturated fats may increase the risk of heart disease. Some fatty acids cannot be made within the body; these are called essential fatty acids and must be obtained from food. Linoleic acid is an essential fatty acid found in plant oils, found in soybean, corn, and sunflowers. - Triglycerides are the main type of lipid stored in the body. They are composed of a glycerol molecule and three fatty acid chains, which can be saturated or unsaturated. Saturated triglycerides are known as fatsbecause they are solid at room temperature. They include animal fats such as butter, lard, cheese, and milk. Unsaturated triglycerides are known as oilsbecause they are liquid at room temperature and include vegetable oils such as olive oil. - Phospholipids are large molecules that contain both hydrophilic and hydrophobic properties. They are composed of a glycerol molecule, two fatty acid chains, and a phosphorous-containing group, resulting in a hydrophilic head that is soluble in water, and a hydrophobic tail that is insoluble in water. These properties allow phospholipids to form a lipid bilayer, the main component of cell membranes. A common dietary phospholipid is lecithin, found in egg yolks, bovine milk, rapeseed, legumes, and cereals. - Steroid molecules are composed of four interlocking carbon rings.Cholesterol is one of the most important steroids in our body. It can be synthesized in the body, but is also obtained from animal products such as eggs, meat, cheese, and fish. Cholesterol is a vital component of cell membranes, and is a precursor to vitamin D and steroid hormones. High levels of ingested cholesterol in the blood may be linked to heart disease, as cholesterol is poorly absorbed in the body. o Fatty acids: - Fatty acids are one of the simplest forms of lipids found in the body. They act as building blocks for the more complex lipids and are used in the synthesis of triglycerides and phospholipids. - Structure: - Fatty acids consist of long hydrocarbon tails topped by a carboxyl group. The hydrocarbon tail is formed by covalent bonds between carbon atoms, which can be either singular or double. The presence of double covalent bonds in a fatty acid chain determines whether or not it is considered unsaturated: a lack of double bonds makes the chain saturated. - Saturated fatty acid - Saturated fatty acids consist of single covalent bonds between the carbon atoms in the chain. The lack of double bonds between the carbon atoms makes the molecules straight. At room temperature, molecules of saturated fat are stacked on top of each other forming a solid. - Example: Palmitic acid - Unsaturated fatty acid: - Unsaturated fatty acids contain at least one double covalent bondbetween carbon atoms in the chain. Unsaturated fatty acids are so called because the double bonds prevent the carbon atoms in the chain from being fully saturated with hydrogen atoms. The presence of double bonds between carbon atoms causes one or more kinks to form in the hydrocarbon tail. At room temperature, unsaturated fats are usually liquid. This is because they are unable to stack closely together and cannot solidify.The number of double bonds denotes the type of unsaturated fatty acid. Unsaturated fats with one double bond are called monounsaturated, and those with more than one double bond are called polyunsaturated. - Example: Oleic acid - Source: - Most fatty acids can either be synthesized by the body, or obtained in the form of triglycerides from the diet.However, some fatty acids are required to maintain a healthy body, and cannot be synthesized by humans. These are called essential fatty acids and must be obtained from food. Important examples of essential fatty acids are omega 3 and omega 6. Alpha-linolenic acid is an omega-3 fatty acid commonly found in vegetable oils, and linoleic acid is an omega-6 fatty acid found in plant oils, such as those derived from soybean, corn and sunflowers. - Function --> energy source - The long hydrocarbon chains of fatty acids contain many energy-rich C-H bonds that, when broken down, are metabolized into energy for cellular processes. Once hydrolyzed, lipids release twice as much energy as carbohydrates. - Function --> ATP synthesis - Lipids, such as fatty acids and triglycerides, contribute to ATP synthesis by feeding into metabolic pathways, such as oxidative phosphorylation. Their catabolism enables the formation of other compounds as well as enabling the production of important intermediary compounds, and eventually, ATP. o Triglycerides: - Triglycerides are the most abundant lipid in both the body and the diet. They are large, insoluble molecules, often consisting of hundreds of atoms, and provide an efficient, compact form of stored energy. Triglyceride molecules are usually stored in adipose tissue, which is mainly found beneath the skin. Triglyceride molecules are too large to pass freely through cell membranes. When they are broken down into free fatty acids and glycerol molecules, they yield large amounts of energy. - Structure: - Triglycerides consist of three fatty acid chainsand a three-carbon glycerol molecule, which acts as the backbone of the triglyceride molecule. They are formed by a condensation reaction between the glycerol molecules and the three fatty acid chains, during which one molecule of water is released for each link formed. The chemical bond formed is known as an ester linkage. - Glycerol backbone: - The glycerol backbone consists of three carbon atoms, to which each fatty acid chain is attached.The glycerol backbone has the same structure for all triglycerides; however, it is the fatty acid chains that vary, producing different types of triglyceride molecules. - Fatty acid chains - Three fatty acid chains are found in a triglyceride molecule. The carboxyl group at the end of each fatty acid chain bonds to the hydroxyl group present on the glycerol molecule. Fatty acid chains vary in their length and degree of saturation. The variations of the three fatty acid chains of a triglyceride determine how solid it becomes at room temperature. - Source: - Triglycerides can either be solid or liquid at room temperature. Saturated triglyceridesare known as fats because they are solid at room temperature. They include animal fats such as butter, lard, cheese, and milk. They are also found in meats, especially red meat such as beef, or lamb. Unsaturated triglyceridesare known as oils because they are liquid at room temperature. They include vegetable oils such as olive oil. Diets high in saturated fat are thought to be associated with an increase in disorders such as heart disease. However, diets high in monounsaturated and polyunsaturated fats are believed to lower the risk of heart disease. - Function --> long-term energy storage - When energy is required, triglycerides are broken down into a glycerol group, and three fatty acid chains. These fatty acid chains can then be metabolized to produce energy for a number of cellular processes. - Function --> Protection - Adipose tissue (tissue containing fat cells) surrounds most of the organs in the body and functions to provide a layer of protection for the organs. - Function --> Insulation and thermoregulation - The layer of adipose tissue surrounding the organs also acts to insulate them. o Phospholipids: - Phospholipids are similar in structure to triglycerides, but a phosphate group takes the place of one of the fatty acid chains. - Structure: - Phospholipids also consist of a glycerol backbone, but have only two fatty acid chains as opposed to three. In addition, a phosphate group is attached to the glycerol backbone, which further adheres to a positively charged group containing nitrogen. This gives the phospholipid its dual polarity (amphipathic), meaning that it contains both a hydrophilic(polar) head and a hydrophobic (non-polar)tail. - Polar head: - The polar head region of a phospholipid is the part that is able to interact with water molecules and form bonds. These properties explain the way in which the phospholipids are arranged within the lipid bilayer of cellular membranes: the polar heads are attracted to the water-rich fluid on the outside (extracellular fluid) and the inside (cytoplasm) of the cell. - non-polar tail: - The two fatty acid chains (tails) that are connected to the glycerol backbone are hydrophobic and do not interact with water. This means that the non-polar tails of the lipid bilayer of cellular membranes repel the water-rich fluid on both sides, leaving them facing each other on the inside of the double plasma membrane. - Source: - The majority of phospholipids are synthesized within the cytosol of cells. A common source of dietary phospholipid is lecithin, found in egg yolks, bovine milk, rapeseed, legumes, and cereals. - Function --> Formation of plasma membranes · Phospholipids form the building blocks of the plasma membranes of cells and perform a vital function by regulating which substances enter and exit the cell. - Function --> Transmission of nerve impulses - The myelin sheath of nerve cells contains a high number of phospholipids, insulating the nerve cell from electrical activity and increasing the transmission of nerve impulses. o Steroids: - Steroids differ significantly in structure from other lipids. Their structure does not involve long fatty acid chains, but instead, involves a characteristic arrangement of carbon rings with different side groups attached.Common steroids found within the body include cholesterol, vitamin D, and the sex hormones estrogen and testosterone. Steroids can also be amphipathic, depending on which groups are added to their non-polar, hydrocarbon rings. - Structure: - Steroids are a type of organic compound that contain four carbon rings that are joined to each other.The most important steroid in the body is the dietary fat cholesterol. Cholesterol has a number of functions within the body, but most importantly is responsible for synthesizing other steroids, including testosterone, estrogen, bile salts, and vitamin D. - Carbon rings: - Steroids consist of three cyclohexane (six) hydrocarbon rings and one cyclopentane (five) hydrocarbon ring, which are joined to one another. Different groups project from these rings, giving each steroid its individual properties. - Hydrocarbon tail: - The hydrocarbon tail is usually found attached to the cyclopentane hydrocarbon ring of the steroid. - Source: - Cholesterol can be synthesized in the body, but is also obtained from animal products such as eggs, meat, cheese, and fish. It serves as a precursor for other important steroids found in the body such as bile salts, vitamin D, and sex hormones. - Function --> Component of cell membranes · Cholesterol is an essential component of cell membranes, which are required to provide sufficient permeability and fluidity. - Function --> Regulation of normal reproductive function - The sex hormones estrogen and testosterone are essential for regulating normal sexual function. - Function --> Digestion and absorption - Bile salts aid in the digestion and absorption of lipids as they cross cell membranes.

Membrane transport

o Membrane transport: - In order to function normally, a cell must allow substances to move into and out from its plasma membrane. Some substances may be nutrients, which are required to help essential chemical reactions take place within the cell, others may be waste materials of these reactions, which must leave the cell to be used by other cells, or be excreted from the body.Selective permeability allows the plasma membrane to regulate what enters and exits the cell. The plasma membrane is selectively permeable as certain substances are permitted to pass through it more readily than others. Permeability may be determined by size, electrical charge, or solubility. In some cases, substances may be completely prohibited from passing through the cell membrane. Substances are able to cross the plasma membrane via a number of different transport mechanisms that can be classified as passive, or active, depending on whether energy is required to facilitate movement. o Gradients across a membrane - The difference in concentration of substances on one side of a membrane compared with the other is known as a gradient. The movement of substances from one side of a membrane to the other can occur in the direction of the gradient, or against it. If substances move in the direction of a gradient, energy may not be required. However, substances move against a gradient, energy is always needed to facilitate the process.Within a cell, there are three main types of gradient: concentration gradient, electrical gradient, electrochemical gradient. § Concentration gradient: - The difference in chemical concentration of a solute from one area to another. § Electrical gradient: - The difference in electrical charge of ions from one area to another forms an electrical gradient known as the potential differenceacross the plasma membrane, or membrane potential. § Electrochemical gradient: - This is the combination of an ion's concentration and electrical gradient. It is the separation of, or difference in, both electrical potential and chemical concentration between two different regions. o Types of membrane transport - The presence of a gradient across a plasma membrane facilitates the movement of substances. This movement can occur by two types of mechanisms: passive transport or active transport. § Passive transport - Passive transport is a simple process in which no energy is required to move particles. Substances move across the plasma membrane down their concentration or electrical gradient. - Examples: - Simple diffusion, facilitated diffusion, osmosis. § Active transport - Active transport is a more demanding process in which cellular energy is required to move substances against their concentration or electrical gradient, or through an impermeable membrane. ATPproduced within the cell is used as an energy source to fuel active transport of substances across the phospholipid bilayer. - Examples: - Primary active transport, secondary active transport, vesicular transport. § Passive transport - Passive transport is also known as diffusion. It is the net passive movement of particles from an area where they are in high concentration to an area where they are in low concentration; down their concentration gradient. This phenomenon occurs because the particles possess intrinsic kinetic energy that causes them to move in a random, high-speed manner, so that they collide with each other. Over time, these collisions cause the molecules to become more evenly distributed within the solution.Both the solute and solvent within a solution undergo diffusion. When the particles have become evenly dispersed and no concentration gradient remains, the solution has reached equilibrium. The rate of diffusion of substances across the plasma membrane is determined by the following factors: - Electrical and concentration gradients: - The larger the gradient, the faster the rate of diffusion. - Temperature: - The higher the temperature, the faster the rate of diffusion. - Membrane thickness/diffusion distance: - The smaller the diffusion distance, the faster the rate of diffusion. - Membrane surface area/diffusion area: - The greater the surface area for diffusion to occur over, the faster the rate of diffusion. - Substance mass: - The smaller the mass of the diffusing substance, the faster the rate of diffusion. - Lipid solubility: - The greater the lipid solubility of the diffusing substance, the greater the permeability of the plasma membrane, and the faster the rate of diffusion. - The selective permeability of the plasma membrane means that diffusion cannot occur freely, however, a particle is able to diffuse across the plasma membrane if it is lipid soluble, small enough to pass through membrane channels, or is assisted by a carrier molecule. There are three main types of diffusion: simple diffusion, facilitated diffusion, and osmosis. o Simple diffusion - When a region of high solute concentration is separated by a plasma membrane from a region of low solute concentration there is a concentration gradient between the two regions. If the solute molecules are small, non-polar molecules like oxygen or carbon dioxide, or lipophilic structures such as steroids, they can diffuse down this concentration gradient by passing directly through the plasma membrane. A membrane channel or carrier protein is not required. This is known as simple diffusion. This process is described as passive, because energy in the form of ATP is not needed for molecules of solute to cross the plasma membrane. Simple diffusion will continue until there is an equal solute concentration on both sides of the membrane. o Facilitated diffusion - Some molecules, for example, highly charged molecules such as sodium ions, or larger molecules like glucose, cannot cross a membrane by simple diffusion. This is because they are too hydrophilic to penetrate the non-polar central region of the lipid bilayer. The movement of these substances across a plasma membrane, therefore, requires the presence of an ion channel or carrier protein within the membrane itself to facilitate diffusion.There are two main types of facilitated diffusion: channel-mediated facilitated diffusion and carrier-mediated facilitated diffusion. o Channel-mediated facilitated diffusion - During channel-mediated facilitated diffusion, solute molecules diffuse down their concentration gradient, from an area of high solute concentration to an area of low solute concentration, by passing through an ion channelwithin the plasma membrane.Ion channels are often very selective, only permitting the passage of a single type of ion. These channels may also be gated, only permitting diffusion to occur when they are open. - Example: - The movement of sodium ions required for neuronal activity in the brain. § Substances involved: - Highly charged molecules (e.g., sodium, potassium, chloride, and calcium ions) - Rate limited by: - The rate of channel-mediated diffusion is determined and limited by the number of ion channels in the plasma membrane and the steepness (amount of difference) of a substance's electrochemical gradient. o Carrier-mediated facilitated diffusion - During carrier-mediated facilitated diffusion, solute molecules diffuse down their concentration gradient, from an area of high solute concentration to an area of low solute concentration, by binding to a carrier proteinwithin the plasma membrane. The carrier protein undergoes a conformational change, which deposits the solute molecule on the opposite side of the membrane. - Example: - The uptake of glucose from the blood into liver cells. § Substance involved: - Large, polar, lipid-insoluble molecules(e.g., glucose and amino acids). - Rate limited by: - The rate of carrier-mediated diffusion is determined and limited by the number of available carrier proteins in the plasma membrane and the steepness of a substance's electrochemical gradient. o Osmosis - Osmosis is the diffusion of water molecules down their concentration gradient, across a semi-permeable membrane.This membrane is semi-permeable because water molecules can pass through it, but solute molecules cannot move as they are too large. - The beaker below shows a semi-permeable membrane separating a solution with a low solute concentration on the left from a solution with a higher solute concentration on the right.There is an overall passive movement of water molecules from the solution with a low solute concentration to the solution with a high solute concentration. This is because the water molecules move to even out any difference in concentration, just like in ordinary diffusion. This net movement of water molecules will cause the water level to rise on the right and fall on the left. § Hydrostatic pressure is the pressure exerted by a fluid due to the force of gravity acting upon it. As the column of water on the right gets higher, the hydrostatic pressure it exerts increases. The hydrostatic pressure acts to push the water molecules back across the membrane, opposing the movement of water by osmosis.At some point, this pressure is high enough to stop the net movement of water through the membrane by osmosis. This pressure is known as the osmotic pressure. § The osmotic pressure is determined by the concentration of non-diffusible solutes in the solutions. If there is a small difference in solute concentration between the two solutions, there is a low osmotic pressure. In this case, a small amount of water crosses the membrane by osmosis, raising the level of the solution on the right slightly. As a result, the hydrostatic pressure increases slightly, which is enough to prevent any further net movement of water. § However, if there is a large concentration difference between the two solutions, there is a much higher osmotic pressure. A large amount of water can cross the membrane, raising the level of the solution on the right considerably, before the hydrostatic pressure will be enough to prevent further net movement of water. o Tonicity § In a normal cell, the osmotic pressure exerted by the cytosol within a cell is equal to the osmotic pressure exerted by the interstitial fluidsurrounding it. As a result, there is no net movement of water, and the cell remains the same shape and volume. If, however, the osmotic pressure exerted by cytosol inside of the cell is different to the osmotic pressure exerted by the interstitial fluid surrounding it, osmosis will occur and the cell will change volume and shape. If water moves from the cytosol out of the cell and into the surrounding fluid, the cell will shrink, and if water moves from the surrounding fluid into the cell, the cell will expand. The measure of the difference in this osmotic pressure is known as tonicity. The tonicity of a solution relative to another solution can be described as isotonic, hypotonic, or hypertonic. o Isotonic solution § The concentration of non-diffusible solutes in an isotonic solution is equal to that of the cytosol within a cell. Therefore, if a cell is placed in an isotonic solution, there is no net water movement and the cell stays the same size. o Hypotonic solution § A hypotonic solution contains a lower concentration of non-diffusible solutes (and, therefore, a higher water concentration) compared with the cytosol within a cell. Thus, if a cell is placed in a hypotonic solution, water moves into the cell, causing it to expand and eventually rupture. This rupturing is known as lysis. When it occurs in erythrocytes it is known as hemolysis. o Hypertonic solution § A hypertonic solution contains a higher concentration of non-diffusible solutes (and, therefore, a lower water concentration) compared with the cytosol within a cell. Thus, if a cell is placed in a hypertonic solution, water is drawn out of the cell, causing it to shrink. This shrinking is known as crenation o Active transport § Active transport uses cellular energy to drive the movement of polar and charged solutes, such as ions, amino acids, and monosaccharides, across the plasma membrane against their electrochemical gradient. There are two main types of active transport: primary active transport and secondary active transport.Vesicular transport is another form of active transport, where adenosine triphosphate (ATP) is required to move larger substances into and out of a cell. There are three main types of vesicular transport: endocytosis, exocytosis, and transcytosis. o Primary active transport § Primary active transport uses specific carrier proteins driven by the energy produced by the hydrolysis of ATP. These carrier proteins, also known as pumps, move various solutes across the plasma membrane against their concentration gradients. The sodium potassium pump, or Na+/K+ATPase, is the most abundant primary active transport carrier protein in the body. o Sodium potassium pump § The sodium potassium pump works constantly to maintain a low intracellular concentration of sodium ions and a high intracellular concentration of potassium ions in the cytosol. The gradients created by the difference in concentration of these ions are important for maintaining normal cell volume, and for generating electrical signals, needed for excitable cells, such as muscle and nerve cells to function. Primary active transport via sodium potassium pumps occurs in the following stages: - The sodium potassium pump binds three Na+ ions from within the cytosol. - ATP then binds to the ATPase region of the pump, and is hydrolyzed to adenosine diphosphate and a phosphate. This phosphate remains bound to the pump, phosphorylating it. - Phosphorylation causes the pump to change in shape. The Na+ ions are released into the extracellular fluid and two K+ ions bind to the pump. - The phosphate group is then freed from the pump, causing the pump to return to its original shape, and release the K+ ions into the cytosol. - The pump thereby returns to its initial state, ready to repeat the process. o Secondary active transport § The concentration of sodium ions in the extracellular fluid is usually substantially higher than in the intracellular fluid, due to the action of the sodium potassium pump. Therefore, there is a strong concentration gradient of sodium ions across the plasma membrane.Because of this concentration gradient, the sodium ions in the extracellular fluid can be described as having 'potential energy'.If there is a route for the sodium ions to diffuse back across the plasma membrane, this potential energy is converted into free kinetic energy. o Antiporter § During secondary active transport, some carrier proteins called antiporters use this mechanism to move sodium ions, and at the same time transport other substances in the opposite direction.Calcium levels are usually higher outside the cell. A sodium/calcium antiporter uses the kinetic energy of sodium ions moving into the cell to transport calcium ions in the opposite direction, against their concentration gradient. Similarly, levels of hydrogen ions can be higher outside the cell. A sodium/hydrogen ion antiporter uses the kinetic energy of the sodium ions moving into the cell to transport hydrogen ions out of the cell, against their concentration gradient. o Symporter § Other carrier proteins, called symporters, use a similar mechanism, but transport substances in the same direction as the sodium. Levels of glucose may be higher inside the cell. A sodium/glucose symporter uses the kinetic energy of sodium ions moving into the cell to transport glucose molecules into the cell at the same time, against their concentration gradient. Levels of amino acids may also be higher inside the cell. A sodium/amino acid symporter uses the kinetic energy of sodium ions moving into the cell to transport amino acids into the cell at the same time, against their concentration gradient. § All these mechanisms are types of secondary active transport because they rely on the electrochemical gradient of sodium ions established by primary active transport. o Vesicular transport § Small, spherical, membrane-bound sacs known as vesicles are used to move substances between organelles within a cell and across the plasma membrane, into and out of a cell. There are three main types of vesicular transport: endocytosis, where substances are moved into a cell, exocytosis, where substances are moved out of a cell, and transcytosis, where substances are moved into, across, and out of a cell. o Endocytosis § Endocytosis is a type of vesicular transport, involving the active movement of substances intoa cell in membrane-bound vesicles. Specific forms of endocytosis occur as a result of receptors present on the cell surface. These receptors are usually highly selective, determining which substances are able to enter the cell. Non-specific forms do not use receptors, but instead, small particles are taken up in small invaginations in the surface of the plasma membrane, which are split off from the cell surface.There are three main types of endocytosis: receptor-mediated endocytosis, phagocytosis, and pinocytosis. o Receptor-mediated endocytosis § A highly selective form of endocytosis that begins when receptors on a cell's surface bind specific substances, triggering the plasma membrane to form a vesicle around them, drawing them into the cell. § Examples: - Vitamins, antibodies, hormones, low-density lipoproteins (LDLs), and the iron-transporter, known as transferrin, are all substances taken up into cells by receptor-mediated endocytosis. o Phagocytosis § A process by which specialized cells, known as phagocytes, engulf, and dispose of large, solid particles such as dead cells and bacteria or viruses, helping to protect the body from invading microbes. It is a specific form of endocytosis, resulting only in the ingestion of much larger solid particles that have not previously been broken down. § Examples: - Macrophages and neutrophils are examples of phagocytes. o Pinocytosis § Also known as bulk-phase endocytosis, pinocytosis is carried out by most cells of the body. It is the process by which small amounts of extracellular fluid along with any dissolved solutes are taken up into the cell. Pinocytosis is a non-specificprocess, where all solutes within the extracellular fluid are transported. § Examples: - Cells that undergo pinocytosis include cells of the kidney, epithelial cells of the intestines, cells of the liver, and capillary epithelial cells. o Receptor-mediated endocytosis § Receptor-mediated endocytosis occurs in the following steps: - A ligand binds to a specific receptor on the cell's plasma membrane, forming a ligand-receptor complex. Each receptor is associated with a protein, known as a clathrin, on the membrane's cytoplasmic side.The regions of the plasma membrane in which these receptors and their associated clathrin molecules are expressed are known as clathrin-coated pits. - The clathrin-coated pit sinks into the cell, forming a vesicle that contains the ligand-receptor complexes. This vesicle becomes detached from the plasma membrane and enters the cytoplasm. - Once in the cytoplasm, the clathrin molecules coating the outer edge of the vesicle leave, and associate with new receptors on the plasma membrane - The uncoated vesicle fuses with an endosome, and the ligands and receptors separate, collecting at opposite ends of the endosome. - Sections of the endosome containing unbound receptors pinch off, forming transport vesicles that return the receptors to the plasma membrane. - The remaining vesicles, which now contain free ligands, fuse with a lysosome containing digestive enzymes. - Finally, the lysosome's digestive enzymes break the ligands down into smaller molecules, which are then released into the cytoplasm of the cell for use in a number of cell processes. o Phagocytosis § Phagocytosis occurs in the following steps: - Receptors on a phagocyte's surface bind to large solid particles such as microbes, dead cells, and debris. - The binding action triggers the plasma membrane to extend finger-like projections, called pseudopods, around the bound particles forming a vesicle, known as a phagosome. - This vesicle becomes detached from the plasma membrane and enters the cytoplasm within the cell. - The phagosome then fuses with a lysosome, which contains digestive enzymes. - The digestive enzymes break down the engulfed particles into smaller molecules, and the digested solutes enter the cytoplasm. - Any remaining undigested material is contained in a vesicle, known as a residual body, which remains in the phagocyte's cytoplasm. o Pinocytosis § Pinocytosis occurs in the following steps: - Droplets of extracellular fluid containing dissolved solutes collect in a pit at the surface of the cell. - The plasma membrane extends around these fluid droplets, forming a vesicle that is drawn into the cytoplasm of the cell. - This fluid-filled vesicle then fuses with a lysosome, which contains digestive enzymes. - Finally, the digestive enzymes break down the extracellular fluid, and the digested solutes are released into the cytoplasm. o Exocytosis § Exocytosis is the active movement of substances out of a cell in membrane-bound vesicles.Every cell in the body actively removes certain materials by exocytosis; however, it is particularly integral to the functioning of certain cells, such as secretory cells, which secrete their products by exocytosis, and neurons, which secrete neurotransmitters by exocytosis. Membrane-bound vesicles form inside the cell, usually in the Golgi complex, and the product containing vesicles then move towards the plasma membrane, with which they fuse, releasing their contents into the extracellular fluid.Exocytosis occurs in the following steps: - Membrane-bound vesicles form inside the cell from the rough endoplasmic reticulumand the Golgi apparatus, or from endosomes or lysomes within the cytosol. - The vesicles, which may contain newly synthesized proteins or waste products, then move toward the plasma membrane. - The plasma membrane and vesicular membrane fuse, and the vesicle contents are expelled into the extracellular fluid. § Examples: - Examples of exocytosis include the secretion of neurotransmitters, hormones, mucus, and digestive enzymes. o Transcytosis § Transcytosis is the active movement of substances into one side of a cell via endocytosis, across the cell, and then out from the other side by exocytosis. § Examples: - During substance exchange between the blood and interstitial fluid, transcytosis occurs across the endothelial cells lining blood vessels

Tactile sensation

- Humans perceive a range of different tactile sensations, including light touch, pressure, vibration, itch, and tickle. This is due to activation of a number of different types of receptors, which respond to different aspects of a tactile stimulus.

The small round spaces which house the mature bone cells are called what? 1. lacunae 2. osteoblast 3. osteon 4. osteoclast 5. osteocyte

1. lacunae

Where would you expect to find the epiphyseal plate in a long bone? 1. epiphysis 2. diaphysis 3. metaphysis 4. diploe 5. medullary cavity

3. metaphysis

The long tubular shaft of a long bone is called what? 1. metaphysis 2. diploe 3. epiphysis 4. diaphysis 5. medullary cavity

4. diaphysis

Identify the large muscle on front of the arm with two heads that have an origin on the scapula and insertion on the radial tuberosity. 1. triceps brachii 2. brachialis 3. pectorals major 4. latissimus dorsi 5. biceps brachii

5. biceps brachii

Hypothesis compared to theory

- A theory is a set of hypotheses that when looked at together form a broad supportive basis to explain a natural phenomenon such as Evolution, Big Bang Theory or Plate Tectonic Theory. In essence, a theory is supported by a large body of evidence generated by many experiments and observations.

Introduction: histology Dr. K's

- A tissue is a group of cells interacting in a common function. There are four basic tissue types, epithelial, connective, muscle and nervous tissues. - EPITHELIAL TISSUE - sheetlike tissue that lines the free surfaces of the body, both the exterior surfaces and interior surfaces. Exterior surface is skin. The interior surface can be the lining of the gut (digestive track) and the lining of the blood vessels. - The space inside the digestive track is outside of the body mass! Food in the stomach or being digested in the intestine is still outside the body mass until it is absorbed into the body mass.

ATP/ADP cycle

- ATP used for synthetic reactions and is broken down to ADP + P. The availability of ADP and P controls the rate of oxidative phosphorylation and how fast glucose is broken down to CO2 and H2O. This means that the flow of electrons down the electron transport pathway is controlled or coupled to ATP formation. If ability to form ATP is eliminated as when knobs on inner membrane of bat brown fat mitochondria are not there, then electrons flow very fast down to

Growth stage

- Also called the anagen stage, cells in the hair matrix multiply and push existing cells superficially. As cells are forced up they become keratinized and die. This stage usually takes about 2 to 6 years in scalp hair.

Resting stage

- Also referred to as the telogen stage, metabolic activity is reduced and the hair eventually falls out after 3 months.

Limits of science

- Although Science has explained much over the past several hundred years and continues to solve many problems and diseases, there are limits to what Science can do or ought to do. - Natural Limits - we cannot know time before Big Bang and cannot measure the position and speed of a subatomic particle because measuring one parameter changes the other parameter (Heizenberg Principle in Physics) or we cannot travel faster than the speed of light. - Self-imposed Limits - fertilizing ape eggs with human sperm is one example of an ethical decision that can impose human-generated limits on scientific endeavors.

Humans created life

- In the middle of May, 2010, it was announced that J. Craig Venter and his team of scientists at the J. Craig Venter Institute created the first synthetic cell, a human creation of a bacterial cell with a computer-generated genome. Within the DNA code of this new form of artificial life are watermark codes to distinguish this bacterium from natural bacteria. The watermark code contains the names of the 46 researchers who worked on this project and quotations from James Joyce, physicist Richard Feynman and J. Robert Oppenheimer and a URL that anyone who deciphers the code can e-mail. - Bacteria are prokaryotes which means they lack a nucleus and their single circular DNA chromosome is floating free in their cytoplasm. Maybe it's also important to know that a virus has already been "created" in the lab but a virus is not considered to be living in that viruses have to be within a living cell to replicate and produce more viruses. Scientists look at the cell as an inter-related mesh of functioning biochemical processes which break down molecules for energy (catabolism) and build up or synthesize molecules for growth (anabolism). All the reactions found in a cell are chemically based so it is easy to think that if you could bring together those reactions, i.e., build them from scratch, you ought to be able to build a cell. This can be viewed as a type of reverse engineering similar to how the Russians following the defeat of Germany in World War II built their first rocket ship. The United States captured Von Braun and some other German rocket scientists so could build rockets with the plans and head scientists they captured. Russia, however, captured the rocket sites and some intact rockets which they took apart, i.e., reverse engineered, to build their rockets and if you recall beat us into space with the launch of Sputnik. So, cell scientists like Venter and his team have reverse engineered a bacterial cell genome and built it from scratch with the help of computers making their creation the first life created by humans. - The idea of scientists "playing God" creeps into the picture. Science and its progress in this area and other areas leads us to ask what does it mean to say that scientists are "playing God". I think that many of us have ascribed certain things we see in life and nature as coming into being only by God. But, what science does is to ask questions and find out if there is evidence that supports that point of view. The evidence comes from experimentation and if the results do not support the hypothesis, then a different hypothesis is tried and new experiments follow. So, if simple life first appeared on this planet billions of years ago according to evolutionary theory, then it follows that we ought to be able to duplicate the events that brought life as we have defined it, i.e., simple cells, into being. Starting from this basis, scientists would argue that they are not really "playing God" as much as attempting to duplicate (and verify) a process that occurred at least once in our history of life on this planet.

cell biology introduction

- Introduction: - Cells are the structural and functional units of all living organisms, primarily formed from the elements carbon, oxygen, hydrogen, and nitrogen. They not only function as individual units, but also as a part of larger structures, namely tissues and organs, where they communicate with other cells, forming co-ordinated functional units. New cells are created by cell division. Once divided, they differentiate into cells specialized for their purpose. These qualites allow them to respond to the body's constantly changing internal and external environments. The human body is composed of many different types of cell, which are generally classified by size, shape, and function. Cells contain numerous small structures called organelles, which carry out specific functions; different cells have different complements of organelles depending on the ultimate function of the cell. There are two main types of cell, germ cells, and somatic cells; germ cells consist of the sperm in the male, and oocyte in the female, and somatic cells include all other cells in the body. Some of the main types of cell are described in the table below. o Types of cells: - Somatic cells - Epithelial cell: o Epithelial tissue forms many of the linings and coverings in the body. Epithelial cells have many functions, including acting as a protective surface, secretory surface, or as an absorptive surface, regulating the movement of substances into and out of the body. Epithelial cells vary in shape depending on their function and location. - Blood cells: - Red blood cells, or erythrocytes, are the most common type of blood cell. These cells bind oxygen in the lungs, and carry it to tissues throughout the body, where it is exchanged for the waste product carbon dioxide. - White blood cells, or leukocytes, function by identifying, capturing, and eliminating invading pathogens, or foreign particles. There are many types of white blood cell, including neutrophils, eosinophils, basophils, monocytes, and lymphocytes. - Bone cell: - Osteoblasts are bone-producing cells present in bone marrow and other connective tissues. They synthesize and secrete collagen fibers, and other organic components, which are used to build the extracellular matrix of bone tissue and initiate calcification. - Fibroblast cell - Fibroblasts are large, flat, branching support cells present in most connective tissue. They secrete fibers including collagen, and some of the ground substance component of the extracellular matrix. These are used to provide the structural framework for tissues. Fibroblast cells also play in important part in skin wound healing. - Muscle cells - Skeletal muscle cells are found attached to the skeleton via tendons, or through a connective tissue sheet called an aponeurosis. Skeletal muscle is under voluntary control and is able to contract, respond to stimulation from the nervous system, stretch beyond its normal resting length, and revert to its original resting length. - Smooth muscle cells are found in the walls of internal organs, blood vessels, and the intrinsic (internal) muscles of the eye. Smooth muscle tissue is involuntary. It helps to propel and expel liquid within and from the body, allows peristalsis that aids in digestion, and helps to regulate the diameter of blood vessels. - Nerve cell - Nerve cells, or neurons, are the main functional cells of the nervous system. They have long extensions that are sensitive to external stimuli, allowing them to respond to, and communicate information through, electrical and chemical signals. - Germ cells - Sperm cell - Found in the male, approximately 300 million spermatozoa or sperm cellsare made in the testes per day. Sperm cells are uniquely designed and have a number of important features, which enable them to travel to and fertilize an ovum. - Ovum - Found in the female, approximately one oocyte, orimmature gamete, is released from the ovary each month during the ovulation process. During the course of each month, the oocyte will travel down the uterine tube until it encounters a sperm cell. If a sperm cell enters the oocyte, fertilization occurs. At this stage, the oocyte is now called an ovum. Within minutes, the sperm and ovum nuclei fuse to form a zygote. - Cells have a variety of different functions. The components of each cell determine its size, shape and function. Some of the most important functions of a cell are described in the table below. - Functions of the cell - Protection and support - There are number of cells that help to protect and support the body. Epithelial cells, such as those found in the skin, provide a protective surface, preventing foreign particles from invading the body. - Communication - The nervous system contains a vast network of specialized neurons that act as a communication system: perceiving, relaying, and conveying information in pathways throughout the body - Energy production - Energy released during cellular metabolism enables cellular activities, such as synthesis, contraction, and heat production to occur. - Movement - Some cells, such as skeletal muscle cells, are able to facilitate movement of the body by contracting and relaxing in response to stimulation from the nervous system § Inheritance - The sex cells, namely sperm cells and oocytes, are responsible for providing inherited genetic information . § Transport - Many cells facilitate the transport of substances within the body. For example, red blood cells bind oxygen in the lungs, and carry it to tissues throughout the body. It can then be exchanged for the waste product carbon dioxide.

Nervous tissue

- Nervous tissue consists of neurons (nerve cells) and neuroglia (a specialized group of support cells). The majority of nervous tissue is found in the brain and spinal cord.

Sensation: Tickle

- Receptor: Free nerve endings - Function: As this sensation cannot be self-induced, it suggests that neural activity associated with your own movement interferes with it.

Epithelial tissue types

- Simple - single layer of cells squamous, cuboidal and columnar attached to basement membrane - Stratified - many layers of cells with only bottom layer of cells attached to basement membrane. Stratified squamous found in top layer of skin. - Pseudostratified columnar - cells appear stratified but they are all connected to the basement membrane so they are pseudostratified not stratified. (found in throat, nasal passages, trachea).

Cutaneous membranes

- The cutaneous membrane refers to the skin covering the surface of the body. - The epithelial layer, known as the epidermis, consists of keratinized stratified squamous epithelium. It forms a waterproof barrier protecting the body from microbes and damaging substances - The connective tissue layer, known as the dermis, consists of areolar connective tissue and dense irregular tissue. It lies deep to the epithelial layer, supporting it and anchoring it to underlying structures. - Specialized groups of cells in the cutaneous membrane produce a variety of secretions, such as sweat and sebum. In addition, follicles in the cutaneous membrane also produce hair. -

Microscopic anatomy of the epidermis

- The epidermis forms the outer covering of the skin. It is composed of four main types of cells: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. - These cells are arranged into the following five layers: the stratum corneum, lucidum, granulosum, spinosum, and basale. The stratum lucidum is found in the thick skin of the palms of the hands and soles of the feet, a common feature of which is that these areas are hair-less. All of these layers rest on a basement membrane which forms the junction with the dermis. - Cells multiply at the basement membrane and move toward the surface, becoming increasingly keratinized. As they move away from the nutrients of the dermis, they die and flake away on reaching the surface.

Epidermis

- The epidermis is the outermost layer of the skin. It is composed of four or five layers, depending on the type of skin. It is rich in a tough protein called keratin and contains four different cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. - The epidermis itself does not contain any blood vessels, but receives nourishment instead from the capillaries in the dermis below. - As cells of the outer surface of the epidermis are continually being sloughed off, some cells in the stratum basale (the bottom layer) of the epidermis divide continuously, replenishing the epidermis. - The epidermis forms a waterproof barrier between the body and the external environment, which resists friction and microbial invasion and prevents water loss.

Epithelial root sheath

- The epithelial root sheath surrounding the hair root and bulb comprises an external and internal component. - The external root sheath is an inward continuation of the epidermis. - The internal root sheath is produced by the hair matrix (see next section) and forms a sheath between the external root sheath and the hair itself.

What type of joint does not show much movement and is located between the breastbone (sternum) and some of the ribs? 1. cartilaginous 2. synovial 3. fibrous

1. cartilaginous

The orbicularis oculi has which one of the following actions? 1. closes the eye 2. opens the eye 3. rotates the eye 4. elevates the eye 5. protrudes the eye

1. closes the eye

If strenuous muscle contraction continues and oxygen runs out, what statement best describes what happens next. 1. glycolysis will begin and accumulate ATP and lactic acid until muscle contraction ceases due to cramping 2. aerobic respiration of glucose from glycogen (stored in muscle) generates needed ATP 3. Creatine phosphate passes phosphate quickly to ADP to make more ATP 4. glucose and fatty acids delivered from bloodstream provides source of energy for ATP production.

1. glycolysis will begin and accumulate ATP and lactic acid until muscle contraction ceases due to cramping

Which muscle below would you use to adduct the hip and flex the knee? 1. gracilis 2. adductor brevis 3. adductor longus 4. adductor magnus

1. gracilis

Which one of the following bones is classified as a flat bone? 1. hip bone 2. tarsal 3. phalanx 4. sphenoid bone 5. patella

1. hip bone

What is the insertion of the latissimus dorsi? 1. humerus 2. clavicle 3. ulna 4. radius 5. scapula

1. humerus

"Ball and socket" joints are examples of what type of joint? 1. hyaline cartilage 2. elastic cartilage 3. fibrocartilage

1. hyaline cartilage

"A bands" are contained entirely within a sarcomere. 1. true 2. false

1. true

Ribs 11 and 12 do not attach to the sternum and are called what? 1. true ribs 2. floating ribs 3. false ribs

2. floating ribs

Cytoplasm

o Cytoplasm: § The cytoplasm is the term used to describe everything that resides between the plasma membrane surrounding the cell, and the nucleus. It is made up of many tiny organelles suspended in a fluid known as cytosol. o Cytosol § Cytosol, also known as intracellular fluid, accounts for over half the total volume of a cell. It stores metabolic substrates, allows chemical reactions to take place, and suspends organelles. o Water § Around 75-90% of cytosol is water, which acts as a solvent for many substances. o Dissolved ions § Concentrations of ions such as calcium, sodium, and potassium within the cytosol are different from those found in extracellular fluid: an important factor in osmoregulation and cell signaling. o Small suspended molecules § Small molecules such as glucose, amino acids, and fatty acids are used as substrates in metabolism. o Large suspended molecules § The cytosol contains significantly larger molecules, such as proteins and nucleic acids, than extracellular fluid. Enzymes form complexes that catalyze the chemical reactions involved in metabolism. o Storage masses § The cytosol contains large molecular masses that function as storage units, such as lipid droplets, which store triglyceride molecules, and glycogen granules, which store glucose. o Nucleus § The nucleus is commonly found in the center of most cells. It is the control center of the cell, and contains most of the cell's genetic materialencoded within DNA molecules. These DNA molecules are arranged and folded into chromosomes. The nucleus controls a cell's activities by regulating gene expression in response to signals acting upon it.All of the cells in the body have a nucleus, except for red blood cells. Without a nucleus, red blood cells do not have the necessary codes and instructions for the synthesis of new proteins essential for reproduction and regeneration. As a result, red blood cells have short life cycles, living only for a few months before degenerating.Cells with large cytoplasmic masses, such as skeletal muscle cells, have more than one nucleus to help cope with the regulation of their extensive cellular material. The nucleus is larger than all other organelles and is compartmentalized into regions that change during the cell cycle. o Nuclear envelope § The nuclear envelope forms a double membrane around the nucleus. It exhibits ribosomes on its outer surface and has nuclear pores spanning the inner and outer membrane. § Inner membrane - The inner membrane is the inner lipid bilayer. § Outer membrane - The outer membrane is the outer lipid bilayer, which is continuous with rough endoplasmic reticulum. § Function: - The nuclear envelope separates the nucleus from the cytoplasm. o Ribosomes § Ribosomes are attached to the surface of the outer membrane. They link amino acids together to produce proteins. § Function: - Protein synthesis. o Nuclear pores § Nuclear pores are transmembrane proteins that span both the outer and inner membranes. Each pore consists of protein subunits arranged around a central channel ten times larger than that of an ion channel. § Function: - They regulate the movement of substances across the nuclear envelope, between the cytoplasm surrounding the nucleus and the nucleoplasm within. Small molecules move across the nuclear envelope by simple diffusion, while larger molecules, such as proteins, move by active transport. o Neoplasm § The nucleoplasm is a jelly-like fluid similar to the cytosol but contained within the nucleus. It contains dissolved ions, nutrients, and other solutes. Nuclear elements suspended in the nucleoplasm include nucleoli and chromatin. o Nuceloi § Nucleoli are spherical bodies with no surrounding membrane, and are composed of DNA, RNA and protein. There are usually one or two nucleoli within a nucleus. They are particularly large in growing cells active in protein synthesis. § Function: - Ribosomal subunits are assembled from ribosomal RNA within the nucleoli, they then pass out of the nucleus through nuclear pores, before being joined together and commencing protein synthesis o Chromatin § The structure of chromatin resembles beads on a string, and is comprised of long threads of DNA wrapped around nucleosomes, each of which is made up of eight globular histone proteins. As cells prepare to divide, chromatin threads coil, condense, and shorten to formchromosomes; a structure less likely to become damaged during cell division. § Function: - Chromatin contains the cell's genetic material in the form of DNA, which when active, is transcribed into proteins. The function of chromatin is to determine which proteins the cell produces. o Organelles § Cytoplasmic organelles are small, specialized structures suspended in the cytosol of each cell. Organelles performs specific processes and chemical reactions essential for growth, maintenance, and reproduction. All cells contain virtually all the same organelles; the difference is in the number, the activity level, and the chemicals produced by the organelles . o Cytoskeleton § The cytoskeleton is a mass of thread-like protein filaments extending throughout the cytosol. There are three main types of protein filaments. o Microfilaments § Microfilaments are composed of very fine actin subunits, distributed around the edge of the cell, just under the plasma membrane. Muscle cells are loaded with actin filaments and another microfilament, myosin. § Function: - Microfilaments provide movement and mechanical support, giving shape and strength to cells (e.g., anchorage of integral proteins, supporting and strengthening microvilli). o Intermediate filaments § Intermediate filaments, such as keratin and neurofilaments, are slightly thicker and they are composed of several different protein subunits. § Function: - Intermediate filaments contribute to cell strength, helping to stabilize the organelles, holding them in place within the cell. These filaments are also used for cell to cell adherence. o Microtubules § Microtubules are the thickest of the cytoskeletal filaments and consist of long tubes composed of tubulin protein subunits. Microtubules extend as spindle fibers from the centrosome during cell division. They also extend into cilia and flagella, and into axon terminals during synaptic transmission. § Function: - Microtubules contribute to cell shape and structure. They also facilitate the movement of organelles (e.g., chromosomes during cell division, secretory vesicles during transcytosis, cilia, and flagella). o Centrosome § The centrosome is a region of cytoplasm situated near the nucleus from which microtubules form. It is composed of centrioles and surrounding pericentriolar material. o Centrioles § The centrioles are filament-like components, made up of nine sets of three microtubules arranged in a cylindrical fashion. They occur in pairs, oriented perpendicular to each other. They double and migrate to opposite ends of the cell in preparation for cell division. § Pericentriolar material: - The pericentriolar material is a mass of tubulin complexes surrounding the centrioles. § Function: - Centrioles are responsible for the formation and growth of mitotic spindles(microtubules), which radiate from the centrosome during mitosis. They also contribute to the formation and growth of microtubules involved in cell shape and movement. o Cilia - Cilia are fine, hair-like extensions of the apical surface of a cell. Microtubules project into each cilium, forming a motile cytoskeleton within. These microtubules are formed by, and extend from, a structure similar to a centriole at the base of each cilium, known as a basal body or a microtubule organizing center. § Function: - Cilia beat back and forth in a co-ordinated manner, moving surrounding fluid over the cell surface, as seen in the cells lining the respiratory tract. Some cilia also provide sensation of the external environment. § Examples: - Olfactory neurons display non-motile cilia to trap odorants.Cells of the respiratory tract contain cilia that move mucus, containing trapped foreign particles, away from the lungs. Cells lining the uterine tubes have cilia for the movement of oocytes towards the uterus. o Flagella § Flagella are elongated extensions of a cell body, with microtubules at the core, extending from a basal body. Flagella are encased in plasma membrane and usually exist at the base of a cell. § Function: - Flagella move in a whip-like fashion, generating forward motion of the entire cell. § Examples: - Each spermatozoon has a single flagellum that helps to propel it through the female reproductive tract, towards the oocyte, in order for fertilization to occur. o Microvilli § Microvilli are tubular extensions of the plasma membrane at the apical surface of a cell. They are immobile, and have actin at their core, forming a supportive scaffolding within. § Function: - Microvilli increase the surface area of a cell for absorption. Some specialized microvilli also function as sensory receptors. § Examples: - Absorptive cells of the intestines and kidneys. o Ribosomes § Ribosomes are composed mainly of the ribonucleic acid known as ribosomal RNA. Each ribosome is composed of a large and a small subunit, produced separately in the nucleolus and adjoined in the cytoplasm. Ribosomes may be free within the cytoplasm, or bound to the surface of rough endoplasmic reticulum (RER). § Function: - Free ribosomes synthesize proteins used within the cell, and ribosomes on the RER synthesize proteins to be secreted from the cell, used elsewhere in the body o Endoplasmic reticulum § The endoplasmic reticulum is a series of membranes distributed throughout the cytoplasm, forming interconnecting tubular cavities and sacs, known as cisternae. Cells contain two types of endoplasmic reticulum: rough endoplasmic reticulum and smooth endoplasmic reticulum. o Rough endoplasmic reticulum § Rough endoplasmic reticulum (RER) is continuous with the nuclear envelope, with ribosomes covering its external surface. § Function: - The ribosomes on the external surface of RER synthesizeproteins such as hormones, enzymes, antibodies, blood proteins, and integral proteins, which are then deposited inside the cisternae to be processed and sorted. Newly synthesized proteins are later either secreted from the cell or inserted into the plasma membrane. o Smooth endoplasmic reticulum § Smooth endoplasmic reticulum (SER) is a continuation of the RER, but with no ribosomes on its external surface. Unique enzymes are exhibited along the SER membranes, catalyzing various reactions. § Function: - Enzymes present in the SER are specific to the individual cell, catalyzing reactions integral to the functioning of that cell. Examples include: o Liver cells: § Liver cells are responsbile for lipid metabolism and synthesis of cholesterol and lipid components of lipoproteins. These cells also breakdown glycogen into free glucose. o Cells of the gonads: § Support cells of the sperm amd oocyte synthesize male and female sex steroid hormones. o Intestinal cells: § Cells of the intestine absorb, synthesise, and transport fat molecules. o Liver and kidneys: § Liver and kidney cells inactivate or detoxify potentially harmful substances such as drugs and carcinogens. o Muscle cells: § Muscles cells store and release calcium ions; important in muscular contraction o Golgi complex § The Golgi complex is similar in structure to SER, with a network of about 3-20 stacked cisternae. However, the Golgi complex is more extensive and more numerous in cells that synthesize and secrete many substances. Proteins that enter the Golgi complex after synthesis undergo post-translational modification. They are then sorted and packaged into vesicles to be transported to the cell surface for storage or secretion from the cell. o Cis face § The cis face of the Golgi complex, also described as the entrance to the Golgi, is the specialized convex cisternae facing the RER. Vesicles fuse with the cis face to enter the Golgi complex. § Function: - The cis face receives and modifies proteins produced by the RER. o Lumen § The lumen of the Golgi complex is the space within the cisternae through which proteins pass when moving between the entry, medial, and exit cisternae. § Function: - The lumen is the site of phosphorylation of proteins during post-translational modification o Cisternae: § The medial cisternae of the Golgi complex are small, flattened, membrane-bound sacs that are curved at the center and have bulbous ends § Function: - They add carbohydrates to proteins, forming glycoproteins, and add lipids to proteins, forming lipoproteins. o Trans face: § The trans face of the Golgi complex, also described as the exit from the Golgi, is the specialized, concave cisternae facing the plasma membrane. Vesicles fuse with the trans face in order to leave the Golgi complex. § Function: - It further modifies molecules and sorts and packages them into vesicles for transport to the plasma membrane. o Vesicle: § Vesicles are spherical, membrane-bound sacs that bud off from the RER and the cisternae. § Function: - They transport substances between organelles and out of the cell. o Lysosomes § Lysosomes are membrane-bound vesicles that bud off from the Golgi complex. They contain various digestive and hydrolytic enzymes that break down large molecules as they fuse with other vesicles. Lysosomes have an acidic core for optimal activity, which is maintained by H+ ions imported by H+ pumps in the lysosomal membrane. Carrier proteins in the lysosomal membrane export digested products out into the cell cytoplasm by excretion. § Function: Lysosomes function to: · Digest large molecules taken into the cell by endocytosis. · Degrade, break down and recycleold, worn-out organelles. · Degrade and break down redundant cells within tissues by autolysis, that is, the cell destroys itself. · Degrade and break down cells and tissue surrounding the cell they reside within (e.g., the sperm releases lysosomes during the acrosome reaction). · Break down stored glycogen. · Break down bone, releasing calcium ions into the blood. o Peroxisomes § Peroxisomes, also known as microbodies, are membrane-bound vesicles that are derived from the endoplasmic reticulum. They are smaller in size than lysosomes, and contain the enzymes oxidase and catalase. § Function: - Oxidase enzymes catalyze the oxidation of substances through the removal of hydrogen atoms; a process that produces toxic hydrogen peroxide, which is then decomposed by the enzyme catalase.Peroxisomes are abundant in the liver where they oxidize alcohol and other harmful substances during detoxification. They are also important in the oxidation of damaging free radicals. o Proteasomes § Proteasomes are large, complex structures made up of four protein rings stacked around a central pore. The two inner rings are made up of subunits containing active protease sites. § Function: § Proteasomes degrade unwanted or damaged proteins by proteolysis; a process during which protease enzymes break peptide bonds, forming peptides, and ultimately, free amino acids. Free amino acids are recycled and used to synthesize new proteins. o Mitochondria § Mitochondria are self-replicating, membrane-bound organelles responsible for producing the energy used to power cells. The number of mitochondria present in a cell reflects its energy requirements; cells that require more energy have a larger number of mitochondria. Mitochondria are the site of the Krebs cycle and the electron transport chain, among other metabolic reactions. o Outer mitochondrial membrane § The outer membrane, similar in structure to the plasma membrane, is smooth and is often attached to surrounding organelles such as microtubules. It is freely permeable to substances due to the presence of large, non-specific channel proteins known as porins . § Function: · -The membrane provides support and protection, and permits the entrance of metabolic substrates to the metabolically active regions of the mitochondria. o Inner mitochondrial membrane § The inner mitochondrial membrane exhibits many enzymes. It is permeable to only a few molecules. § Function: - The enzymes within the inner membrane catalyze the chemical reactions involved in the cytochrome system andoxidative phosphorylation o Cristae § Cristae are the in-foldings of the inner mitochondrial membrane. They are at their most numerous in cells with high metabolic rates. § Function: - The cristae increase the surface area over which chemical reactions can take place inside mitochondria. o Matrix § The central cavity within the inner mitochondrial membrane is filled with a fluid matrix containing enzymes, ribosomes, and mitochondrial DNA. § Function: - The enzymes within the matrix catalyze the chemical reactions involved in the Krebs cycle. Synthesis of proteins needed for mitochondrial functioning occurs on free ribosomes and is directed by mitochondrial genes.

A type of bone cell that helps to break down the bone matrix in the bone remodeling process is called what? 1. osteoclast 2. osteoblast 3. osteocyte 4. osteon 5. lacunae

1. osteoclast

joints form the soft spots on a baby's head. 1. synovial 2. cartilaginous 3. fibrous

3. fibrous

what anatomic feature on the scapula is the site of articulation with the head of the humerus? 1. olecranon fossa 2. acromion 3. glenoid fossa 4. trochlear notch 5. medial epicondyle

3. glenoid fossa

During muscle contraction, when calcium ions bind to ___________, the binding site on the actin filament is uncovered. 1. myosin 2. tropmoyosin 3. troponin 4. cross bridges

3. troponin

MUSCLES OF MASTICATION

Temporalis - large, fan-shaped muscle on lateral surface of head with origin on temporal bone, insertion on coronoid process of mandible and action of elevating and retracting the mandible to allow for chewing. If you tightly close your jaw, this muscle may be felt contracting in the temporal region. Masseter - powerful muscle located on side of the face over jaw with origin on zygomatic bone, insertion on mandible (coronoid process) and action of elevating and retracting mandible. When jaw is tightly closed, this muscle bulges out near angle of jaw.

energy transfer

o Energy transfer: - Energy gives living organisms the capacity to be active. Energy is, therefore, vital for the functioning of all the processes in the body. There are several types of energy found in the body: potential, kinetic, sound, thermal, and chemical. Energy can be transferred or stored in many different ways and forms. o Forms of energy: - There are two important types of energy within the body: potential and kinetic. Different forms of energy can be transferred and converted from one form to another. For example, a moving skateboard has kinetic energy. At the top of a ramp, the skateboard has potential energy. When it moves down the incline and gains speed, the potential energy stored is transferred to kinetic energy as it reaches the bottom. o Potential energy: - Potential energy is stored energy. Chemical energy is a type of potential energy that is stored in the bonds between atoms in compounds and molecules. o Kinetic energy: - Kinetic energy is energy associated with matter in motion. Objects in motion (e.g., falling and rolling) possess kinetic energy. There are different forms of kinetic energy: thermal, rotational, and translational (moving from A to B). The amount of kinetic energy an object has depends on its mass and speed, i.e., the higher an object's mass and speed, the more kinetic energy it will have. The different forms of kinetic energy can be converted from one form to another. o Chemical reactions: - A chemical reaction is a process by which new molecules or compounds are made, through the creation of new bonds, or by which molecules or compounds are broken down, through the rearrangement of bonds. A typical chemical reaction involves reactants (the starting substances) and products (the end materials). The reactant molecules must collide with each other in order to react together. o Types of chemical reaction: - There are two types of chemical reactions: exergonic reactions, which release energy and break bonds, and endergonic reactions, which absorb energy and form bonds. The way in which the chemical energy stored in chemical bonds is utilized determines the type of reaction: o Anabolic (synthesis) reactions: - Anabolic reactions involve the synthesis of new molecules from small units, in most cases creating a larger product than the initial reactants. Anabolic reactions are usually endergonic.A and B are the reactants, and AB is the larger end product. o Catabolic (decomposition) reactions: - Catabolic reactions involve the breaking down (decomposition) of existing molecules into smaller end products, e.g., atoms, ions, or smaller molecules. Catabolic reactions are usually exergonic. AB is the larger reactant, and A and B are the smaller end products. o Exchange reactions: - Exchange reactions are chemical reactions that encompass both anabolic and catabolic reactions. Exchange reactions occur when two sets of reactants react to form two sets of products. During such reactions, both sets of reactants undergo catabolism and separate anabolism with the partner of the other reactant to form two completely new products. The first elements, A and C are positively charged, and the second elements B and D are negatively charged. When the atoms in each of the molecules 'switch partners', the positively charged element from one reactant, combines with a negatively charged element of the second reactant to create two new products, AC and BD. o Reversible reactions: - The anabolic, catabolic, and exchange reactions described previously occur from the left-hand side of the equation to the right-hand side in the direction the arrow is pointing. Reversible reactions, however, are chemical reactions that can proceed in either direction. Not only can the reactants create the products, as before, but the products can also be converted back into their reactants. Reversible reactions are usually denoted by two half arrows.Most reversible reactions in the body require enzymes. o Reaction rates and activation energy - The rate of a chemical reaction is influenced by several factors, and the progression of a reaction can be studied using an energy level diagram. Energy level diagrams show the potential energy of reactants and products as well as the resultant change in energy as the reaction progresses. The activation energy of a chemical reaction represents the investment of energy required to initiate the reaction. Energy for a reaction is often absorbed from the surrounding environment. This means that the conditions of this environment are important and can influence the rate and progression of a chemical reaction. o Reaction rate: - The rate of a chemical reaction can be determined by looking at the concentration of reactants and products. Four factors influence the reaction rate: concentration of reactants, temperature, activation energy, and presence of a catalyst. o Concentration of reactants - The concentration of reactants affects the probability of collisions occurring between the reactant particles. The greater the concentration, the more likely the reactant particles will collide and thus react with one another. o Temperature: - Temperature can also have a significant effect on the chance of particles colliding and the speed of a reaction. Increased temperature increases the kinetic energy of the particles involved in the chemical reaction, enabling them to move more quickly and thus collide more frequently. o Activation energy: - Activation energy is defined as the minimum level of energy required to cause a reaction to proceed; it is the energy required to break chemical bonds through collisions between molecules. The higher the activation energy, the slower the reaction rate. o Catalyst: - Catalysts are substances that can lower the activation energy required to start a reaction. If a catalyst is present during a chemical reaction, it speeds up the reaction rate.In the body, many enzymes act as catalysts.

a mature bone cell is called what?

osteocyte

Gross anatomy of the skin

- The skin is composed of two layers: the outer epidermis and the deeper dermis, both of which rest on the hypodermis.

is the radius on the medial or lateral side of the forearm when the arm is in the anatomic position? 1. lateral 2. medial

1. lateral

Choose the insertion of the levator palpebrae superioris muscle. 1. temporal bone 2. lesser wing of sphenoid 3. zygomatic bone 4. modiolus 5. superior tarsus (eyelid)

5. superior tarsus (eyelid)

which of the following is not found in fast twitch muscle fibers?

found in large muscles like the gluteals

which part of the temporal bone has the zygomatic process and the mandibular condyle?

squamous part

The largest sinuses in the skull are located in the occipital bone. 1. true 2. false

2. false

The nose is formed mostly from bone. 1. true 2. false

2. false

What type of contraction describes a muscle that changes length but tension stays the same? 1. isotonic contraction 2. isometric contraction

1. isotonic contraction

Accessory structures of the skin

- Accessory structures of the skin include the sebaceous glands, sweat glands, hair, nails, and sensory receptors. - The accessory structures have a variety of functions: glands function to lubricate the skin and, along with hairs, help to control body temperature. Nails help to protect the skin, and sensory receptors relay information regarding touch, temperature, pain, and proprioception to the brain.

Support cells

- All support cells share the following common characteristics. 1. They are derived from embryonic cells called mesenchymal cells. 2. They start life as immature blast cellscapable of cell division and secretion of extracellular matrix. 3. They produce most of their extracellular matrix materials before differentiation into mature cyte cells. 4. In their mature form, they sit within their matrix, forming sparsely cellular connective tissues, where they continue to maintain the matrix. 5. They adhere to their extracellular matrix materials, rather than adjacent cells. - Support cells are classified according to the type of tissue they produce. - Examples of support cells include the following: - Fibroblasts: Fibroblasts are large, flat, branching cells present in most connective tissue. They secrete fibers including collagen, and some of the ground substance component of the extracellular matrix. - Adipocytes: Adipocytes (fat cells) are highly specialized support cells that store lipidswhich can be metabolized to provide energy. They are present under the skin and surrounding various organs, where they also function as protective padding. - Chondroblasts: Chondroblasts are small, rounded cells with small nuclei, and are found in cartilage, where they secrete components of the extracellular matrix. - Osteoblasts: Osteoblasts are mononucleate cells that secrete the extracellular matrix components of bone. - Myofibroblasts: Myofibroblasts are differentiated fibroblasts committed to becoming smooth muscle cells. They have contractile properties and also secrete extracellular matrix components. - Other cells, whose primary function is not support, may also be present in connective tissue, including: - Mast cells: Mast cells (mastocytes) are present in several tissue types. They are predominantly located near blood vessels supplying the tissues, and at the junction between the external environment and internal milieu, such as the skin and the mucosal membranes of the lungs and digestive tract. Mast cells store and secrete histamine and heparin in response to various stimuli, and are involved in a number of processes, including inflammatory processes, and allergic response - White blood cells: White blood cells migrate from blood to connective tissue during times of need, and gather at sites of infection, parasitic invasion, or allergy. They include macrophages and lymphocytes such as plasma cells. - Macrophages are a type of white blood cell with an irregular, branching morphology. They destroy bacteria and cellular debris by phagocytosis. Macrophages may be fixed, where they reside in a particular tissue, or wandering, where they travel between various tissues, collecting at sites of infection or inflammation. - Plasma cells are important in the immune response, secreting antibodies that attack potentially harmful foreign substances in the body. They are found in connective tissues of the respiratory and gastrointestinal tracts, salivary glands, lymph nodes, spleen, and red bone marrow.

Meissner's corpuscle

- Also called tactile corpuscles, Meissner's corpuscles are egg-shaped, encapsulated masses of dendrites. - Located in the dermal papillae of hairless skin, and found in abundance in the hands, feet, lips, and external genitalia.

Apocrine

- Apocrine glands are less common. Their product accumulates at the apical surface of the secreting cell until that portion of the cell is cleaved from the rest of the cell as part of the secretion. The cell subsequently repairs itself and the process is repeated. - Mammary glands secrete fat droplets into milk by an apocrine mechanism - NB. Sweat glands, originally thought to be apocrine glands, have recently been reclassified as merocrine glands.

Appositional growth

- Appositional growth occurs at the outer surface of cartilage, starting later in life than interstitial growth and continuing through adolescence. The cells of the inner cellular layer of the perichondrium overlying the cartilage differentiate into chondroblasts, and produce extracellular matrix. As the chondroblasts become embedded in extracellular matrix, they mature into chondrocytes. Thus new cartilage forms beneath the perichondrium, adding thickness to the pre-existing cartilage.

Bone

- Bones function to move, support, and protect various organs of the body. They also store calcium and phosphorus, house red bone marrow for red blood cell production, and contain yellow bone marrow for triglyceride storage. There are various different components of bone, made up of different types of connective tissue. These include bone itself, periosteum around the outside of bone, endosteum which lines its central cavity, and red and yellow bone marrow. - There are four main types of cells involved with the production and maintenance of bone. These are: osteoprogenitor cells(stem cells that differentiate into osteoblasts and osteocytes), osteoblasts(actively synthesizing and secreting cells), osteocytes (mature osteoblasts, surrounded by mineralizing bone matrix), and osteoclasts (actively breaking down/resorbing bone). - Bone is classified according to the arrangement of its cells and extracellular matrix as either dense compact bone, which appears smooth and homogeneous, or less dense spongy bone, which has alatticed appearance.

Carbohydrates

- Carbohydrates may be a simple as a single sugar molecule or composed of many sugar units. - Three types of carbohydrates: - monosaccharides - one sugar unit such as glucose -oligosaccharides - short chain of sugar units such as sucrose composed of glucose and fructose (table sugar) - polysaccharides - large polymers of sugar units such as glycogen or starch

Basic organic chemistry

- Carbon can form four bonds with other atoms such as other carbon atoms, hydogen, oxygen and nitrogen atoms. - Carbon can also form ringed compounds and large polymers

Cardiac muscle

- Cardiomyocytes (cardiac muscle fibers) have a diameter of approximately 20-30 μm and a length of around 120 μm. In cross-section, they tend to be less circular than skeletal muscle fibers. Cells are branched and tightly joined to each other by specialized junctions known asintercalated discs. - Intercalated discs exhibit desmosomeswhich strongly connect adjacent cells together, preventing separation during cardiac muscle contraction. Intercalated discs also exhibit gap junctions that mediate the conduction of action potentials through the heart by permitting the flow of ions between cardiomyocytes. This allows the muscular tissue of the heart to produce synchronized contractions. These involuntary contractions of the cardiomyocytes are the basis of our heartbeat, and are responsible for the distribution of blood around the body. - Cardiomyocytes have large, abundant mitochondria for energy production and one or two centrally located nuclei.

Cartilage

- Cartilage is a type of mature connective tissue, made up of a dense network of collagen or elastic fibers and the associated glycosaminoglycan chondroitin sulfate. The collagen fibers provide cartilage with its strength, and the gel-like chondroitin sulfate ensures a high resilience, enabling cartilage to resume its original shape after deformation. - Cartilage extracellular matrix is deposited by chondroblasts, which ultimately mature and become the less metabolically active chondrocytes. Chondrocytes sit in spaces within the extracellular matrix called lacunae. - The secretion of antiangiogenesis factor by cartilage prevents it from developing a blood supply. This limits the formation to cartilage structures to thin layers, and can also lead to poor tissue repair after injury. - A sheet of dense irregular connective tissue known as the perichondrium covers the surface of cartilage. Perichondrium consists of an outer fibrous layer of collagen fibers, fibroblasts, and blood vessels, and an inner cellular layer composed of undifferentiated cells, capable of developing into chondroblasts and chondrocytes, which promote cartilage growth and repair. The vascular perichondrium is vital for maintaining supplies of nutrients to the avascular cartilage - Cartilage is classified as hyaline cartilage,fibrocartilage, or elastic cartilage based on its fibrous protein content.

Tissue repair

- Cells become damaged and die constantly, so new cells must be produced to replace them. This is achieved by cell division and the process of differentiation. - During differentiation, pluripotent cells mature and develop the characteristics of a specific cell type. In the epidermis for example, cuboidal cells produced by the division of pluripotent basal cells start to produce keratin and take on a stratified appearance. As a result, these cells are no longer pluripotent and have become specialized (or differentiated). - The cells undergoing division and differentiation may originate from either the parenchyma or stroma of a tissue or organ: parenchymal cells form the functional parts of a tissue or organ, while stromal cells form the structural framework of the tissue or organ. In the liver for example, the hepatocytes involved with the major functions of the liver, such as protein synthesis, are part of the parenchyma, whereas the fibroblasts in the connective tissue are part of the stroma. - Full tissue regeneration is possible if parenchymal cells divide and differentiate to form fully functioning new tissue. However, if only stromal fibroblasts divide and differentiate, non-functioning scar tissue is formed. This process is known as fibrosis. During repair of extensive tissue damage, the effective combination of parenchymal and stromal cell division and differentiation, and the development of new blood vessels, forms what is known as granulation tissue. This forms across the wound, acting as a protective barrier, promoting the migration of epithelial cells, and producing a defensive, bactericidal serum. Nutrients, such as protein and vitamins, and good blood circulation, are vital for the effective repair of body tissues - Different tissue types renew and replenish damaged or dead cells differently: - Epithelium: Epithelium is often under constant heavy wear and tear and therefore must be highly regenerative. This occurs either by division and differentiation of stem cells (e.g., in the epidermis) or by division of mature, differentiated cells (e.g., endothelial cells). - Connective tissue: Connective tissue is also under constant stress, and continually renews and replenishes cells. A good blood supply, such as in bone, promotes repair. - Muscle tissue: Muscle tissue has a relatively poor capacity for the repair of dead or damaged cells. - Skeletal muscle contains specialized stem cells, called satellite cells, but their slow division means they are only capable of repairing limited damage. - Cardiac muscle is completely lacking in stem cells capable of mitosis for tissue repair. However, the migration of stem cells to the heart from other regions of the body has been suggested as an alternative repairing mechanism. - Smooth muscle is capable of slow and limited repair. -Nervous tissue: The most common response to the damage of nervous tissue is gliosis: the formation of scar tissue composed of astrocyte glial cells. - Until relatively recently, it was believed that adult nervous tissue contained no stem cells and as such, had virtually no capacity for repair. However, it has recently been discovered that certain areas of the adult brain do indeed possess neural stem cells, although to what extent they are capable of repairing damage to neurons or neuroglia is still uncertain.

Nervous tissues

- Cells of nervous tissue termed neurons and neuroglia. Neurons carry electrical impulses or messages and neuroglia are like the connective tissue of the nervous system. - Neuron Structure - consists of a cell body containing nucleus, dendrites bringing impulses to cell body and axon bringing impulse away from cell body. - A nerve is a bundle of individual neurons and may be visible to the naked eye although a neuron may no - Nervous Tissue function is to detect changes in internal and external environment to enable body to respond to the changes

ceruminous glands

- Ceruminous glands are modified apocrine sweat glands located deep in the subcutaneous layer of the external ear. The secretory ducts can either combine with those of the sebaceous glands, or open independently and directly into the external auditory canal. The secretions of the ceruminous and sebaceous glands combine to form cerumen, or earwax. This waxy secretion traps foreign particles and prevents their progress further into the ear, and also reduces the risk of bacterial and fungal infection.

Compact bone

- Compact bone (or cortical bone) forms the rigid, protective outer layer of all bones, as well as the shaft of long bones, such as the femur (bone of the thigh). Due to its dense nature, it accounts for approximately 80% of the total bone mass. - Structurally, it is made up of repeating units that run longitudinally within the bone, known as osteons or Haversian systems. Each osteon contains a central canal, also called a Haversian canal, containing blood vessels and nerves. The central canals and their neurovascular contents are interlinked by perforating canals, also called Volkmann's canals, which run transversely. - Surrounding each central canal are concentric rings of extracellular matrix known as lamellae, consisting of mineralized calcium and phosphates and collagen fibers. - Lamellae provide hardness through their mineral content and strength through collagen fibers. The compact nature of this bone is due to the densely packed arrangement of these lamellae. Small spaces exist between the lamellae, known as lacunae, which contain mature osteocytes. Small canals called canaliculiproject from the lacunae and contain cytoplasmic projections from the osteocytes, through which the osteocytes are able to receive nutrients and remove waste products.

Conduction

- Conduction is the transfer of heat between two objects in contact, e.g., if you sit on a cold stone floor, the heat from your body will transfer to the stone and as a result, you will become cooler. Vasodilation brings more warm blood to the surface of the skin, thus increasing heat loss to the external atmosphere via conduction. Vasoconstriction has the opposite effect.

Connective tissue

- Connective tissue is the collective term for support cells and associated extracellular matrix. The extracellular matrix, usually secreted by the support cells themselves, is composed of an unstructured ground substance which fills the space between the support cells, and contains fibers with various properties. - Connective tissue is extremely abundant and is distributed widely throughout the body. There are many different types of connective tissue, whose properties are determined by the types of support cells, the composition of the ground substance, and the type and arrangement of the various fibers. - Different types of connective tissue have different functions, which may includestructural support and strength, protection, insulation, and storage. Connective tissues have a rich blood supply with the exceptions of cartilage, which is avascular, and the connective tissue that makes up tendons, which has a very poor blood supply.

Connective tissues

- Connective tissues are formed of cells, fibers and a matrix material. .a. Connective Tissue Proper composed of several types such as Dense Irregular Connective Tissue which forms areolar connective tissue around blood vessels and organs. Dense Regular Connective Tissue contains many parallel collagen fibers; which resist being stretched and form tendons and ligaments. b. Cartilage - cartilage cells are called Chondrocytes and exist within little spaces called lacunae. Cartilage types include hyaline cartilage which covers ends of bone, and supporting elements for the trachea. Elastic cartilage contains elastin, a protein making elastic cartilage flexible; forms support for ear. Fibrocartilage packed with collagen fibers and forms intervertebral disks. c. Bone - bone cells are called osteocytes, bone matrix is hardened but contains collagen fibers. Compact bone found forming shaft of bones and spongy bone found toward ends of long bones and in flat bones of skull, pelvis and breastbone. Spongy area filled with bone marrow. d. Adipose Tissue - fat cells which appear as signet rings with the inner space filled with fat and the nucleus appearing as the stone in the signet ring. e. Blood - unusual form of connective tissue because matrix is fluid and fibers in the form of fibrin, are soluble until blood clots and then fibrin fibers form to assist in clot formation - Formed elements of blood consist of RBCs, white blood cells and also platelets derived from megakaryocytes in bone marrow. On average, males have more RBCs than do females. About 10% of our body's weight is blood. - Muscle - Three types of muscle tissues: a. Skeletal Muscle Tissue - long cells, multinucleated and attached to bone usually; skeletal muscle under our conscious control (voluntary control). Organized actin and myosinfilaments (muscle contractile proteins) make muscle strands appear striated. b. Smooth Muscle Tissue - smaller cells than skeletal and have a single nucleus. Found lining digestive tract, bladder, uterus and many other internal organs. Smooth muscle tissue is not able to be directly controlled by our conscious thought therefore is termed involuntary muscle. c. Cardiac Muscle - contractile muscle of the heart. Muscle fibers (cells) are branched with single nucleus. Ends of cells are tightly bound and when stained properly appear as intercalated disks. Intercalated disks have many desmosomes helping to hold ends of cells together.

Convection

- Convection is the transfer of heat away from an object via the movement of gases or fluids. For example, when the air around the body is warmed by radiation, this air rises, moving away from the body into the surround atmosphere. Thus the air adjacent to the skin is replaced by cooler air. As a result, a greater contrast between the temperature of the skin and the surrounding air is maintained, which enhances heat loss. Piloerection, wherearrector pili muscles in the skin contract, pulling the hair up perpendicular to the skin's surface, traps air and reduces convectional heat loss. In many animals, this is an important response. However, as humans have a relatively little body hair, this mechanism is of minor importance.

How does protein synthesis occur?

- DNA -> RNA -> protein - Transcription = DNA -> RNA (think of yourself transcribing your rough notes from a class lecture to more organized notes on another piece of paper, the language is the same, English to English from one paper to another piece of paper) In this case, the code is being transcribed from one nucleic acid (DNA) to another nucleic acid (RNA) - Translation = RNA -> protein (think of yourself translating an article in Spanish to English, here the language has changed and in molecular biology, a nucleic acid (RNA) code has been translated into the amino acid language of the proteins.

Growth and keratinization

- Dead keratinocytes from the stratum corneum flake from the skin due to friction caused by normal wear and tear. New cells must be formed at the stratum basale at the same rate at which they are lost at the surface. This is necessary in order to maintain constancy in the thickness of the epithelium. When the superficial layers of the epidermis are removed, the rate of cell division in the stratum basale increases to compensate for this loss. Epidermal growth factors are associated with the overall regulation of skin growth. - As the cells in the stratum basale multiply and keratinocytes are produced, existing cells are pushed out towards the surface of the skin. Keratin is added to the cells during a process known as keratinization, which occurs in the stratum granulosum. Here, keratin proteins are incorporated into longer keratin intermediate filaments. Eventually, the nucleus and organelles of the cell disappear, metabolism ceases, and cells undergo a programmed death as they become fully keratinized. - The whole process typically takes about four weeks until the cells are sloughed away and shed. Cells become less metabolically active as they advance through the epidermal layers, as less nutrients are available to them. The dermis contains blood vessels, so oxygen and other nutrients necessary for metabolism are only readily available to the deepest epithelial cells, i.e. those nearest to the basement membrane. Those cells relatively far away from nutrient supply cannot maintain their metabolic activity and therefore die. - Keratinocytes move through the epidermal layers and undergo a series of structural changes: - Stratum basale: New stem cells, keratinocytes, and melanocytes are produced at the basal membrane, pushing the older cells towards the surface. Cells here are cuboidal-shaped, and highly metabolically active. - Stratum spinosum: Cells here are alive and joined together by desmosomal connections. Langerhans cells, epidermal dendritic cells, and melanin granules are also present in this layer. - Stratum granulosum: Keratinocytes mature here and produce keratohyalin granules, which produce keratin, and lamellar granules, which produce glycolipids. - Keratin strengthens the cells, while glycolipidsadhere the cells to one another and are responsible for the waterproof properties of skin. - As they approach the stratum corneum, the keratinocytes become increasingly packed with keratin, and further away from an adequate supply of nutrition. As a result, they start the process of controlled cell death, sometimes described as a specialized type of apoptosis - Stratum lucidum: Here, the keratinocytes are dead. The cells appear clear and have thickened plasma membranes. - Stratum corneum: Cells here are dead, flattened, and engorged with keratin, but contain little else. These cells are 'sloughed off' and flake away.

Pacinian corpuscle

- Pacinian, or lamellated, corpuscles are large oval structures, consisting of a dendrite wrapped in a multilayered, connective tissue capsule. Pacinian corpuscles adapt rapidly to stimuli and are involved in sensing pressure. - Located throughout the body in the dermis, subcutaneous layer, and deeper regions (e.g. muscles)

Deep wound healing

- Deep wound healing occurs after an injury that penetrates the dermis, thus the healing process is more complex as different tissue levels must be repaired. Normal structure and function is not always completely restored due to the formation of scar tissue. There are three phases of deep wound healing: - Inflammatory phase: Fibrin and blood platelets form a blood clot in the wound to prevent further blood loss and to seal the injury from the external environment. This is known as hemostasis. This clot connects the interior borders of the wound. The damaged tissue causes the inflammatory factor histamine to be released, which in turn triggers vasodilation, increasing the permeability of the blood vessels. This increases the rate at which microbes, foreign particles, and dying tissue are cleared from the wound site prior to repair, as phagocytic white blood cells have greater access. - Proliferation and migratory phase: Two or three days later, the proliferation and migratory phase begins. Epithelial cells then migrate across the basal surface of the scab to connect the borders of the wound. Fibroblasts migrate along fibrin threads and secrete collagen to strengthen the clot, and blood vessels begin to grow back. Granulation tissue is the name given to the delicate tissue that grows in this phase under the scab. Fibroblasts also trigger the endothelial cells surrounding the wound to proliferate underneath the scab. Collagen fibers are deposited by fibroblasts in a random arrangement, and the blood vessels continue to grow. - Maturation and remodeling phase: The third phase is the maturation and remodeling phase, which can last from 3 weeks to 6 months. The scabs slough off, collagen fibers become more organized, and fewer fibroblasts are present. The blood vessels are restored to normal. - The healing of a deep wound often leads to scarring (fibrosis). Fibrosis is the formation of scar tissue. There are several differences between scar tissue and undamaged skin: scar tissue has a higher density of collagen fibers, reduced elasticity, and might not develop the same number and variety of accessory structures, e.g., sweat glands and hair follicles present in healthy skin. The arrangement of collagen fibers and relative lack of blood vessels is the reason why scars are often a lighter color than the surrounding skin.

Dense connective tissue

- Dense connective tissue consists of many thick, tightly packed fibers with very few supporting cells. - Several types of dense connective tissue exist: - Dense regular connective tissue: Dense regular connective tissue consists of uniformly arranged, parallel bundles of collagen fibers. It is strong and pliable, but withstands stretching only in the direction of the fibers. Fibroblasts are arranged in rows between the collagen fibers and they secrete both ground substance and fiber components of the tissue. It is poorly vascularized. - Tendons and ligaments are made up of dense regular connective tissue. - Dense irregular connective tissue: Dense, irregular connective tissue occurs in sheets, made up of an irregular arrangement of tightly packed collagen fibers. It is strong and pliable and withstands tension forces exerted in all directions. - The dermis of the skin, fibrous pericardium around the heart, heart valves, perichondrium surrounding cartilage, and periosteum surrounding bone, are all made up of dense irregular connective tissue. - Elastic connective tissue: Elastic connective tissue mainly consists of branching elastic fibers and fibroblasts. It is strong and elastic, returning to its original shape after being stretched. - The lungs and elastic arteries both contain elastic connective tissue, giving them the elasticity needed for breathing and the maintenance of blood flow, respectively.

Dermatan sulfate

- Dermatan sulfate is present in the skin, tendons, blood vessels, heart valves, and lungs. It has roles in coagulation, wound repair, and scarring.

Synovial membranes

- Synovial membranes consist exclusively of connective tissue and are found lining the cavities of mobile joints. A layer of areolar and adipose connective tissue overlies a discontinuous layer of secretory cells known as synoviocytes. Synoviocytes secrete synovial fluid components into the synovial cavity of a joint, providing lubrication and nourishment to the cartilage. Synovial fluid also contains macrophages, which engulf microbes and foreign particles.

Elastic cartilage

- Elastic cartilage, unlike elastic connective tissue, is made up of a thread-like network of elastic and collagen fibers, interspersed with chondrocytes in their lacunae. It is strong and elastic, providing and maintaining the shape of various structures. - Elastic cartilage forms the auricle of the ear, the walls of the external auditory meatus and Eustachian tube (pharyngotympanic tube), and the epiglottis of the larynx. It is covered by perichondrium. - Growth and repair of cartilageCartilage is fairly inactive. It lacks a blood supply and therefore grows slowly as the substances and cells needed for repair and growth must diffuse or migrate into the region of inflamed or damaged cartilage. Growth of cartilage may occur interstitially or appositionally.

Epidermal wound healing

- Epidermal wound healing occurs when the epidermis has been damaged, often by minor burns (first degree) and abrasions. Following an injury to the epidermal layer, cells in the stratum basale break off from the basement membrane. The basal epithelial cells then enlarge and migrate across the wound. Individual cell migration stops when two epidermal cells meet one another, in a cellular process called contact inhibition. The migratory phase stops completely when each epidermal cell is in contact with other epidermal cells on all sides. - Throughout the migration of cells, a growth factor known as epidermal growth factoris released into the surrounding area. This stimulates basal stem cells to divide and replace the basal epithelial cells that have relocated. Those basal epithelial cells subsequently divide to produce new strata.

Functional classification of exocrine glands

- Exocrine glands may also be classified according to how their products are secreted. In all glands, synthesis of the product occurs on ribosomes of the rough endoplasmic reticulum, from where it is transferred to the Golgi apparatus and packed into secretory vesicles near the apical surface. The product may then be secreted via merocrine secretion, apocrinesecretion, or holocrine secretion.

Exocrine glands

- Exocrine glands may be unicellular ormulticellular: - Unicellular: Unicellular exocrine glands consist of a single secreting cell. - For example, mucus-secreting goblet cells. - Multicellular: Multicellular exocrine glands are made up of many cells. - For example, sweat glands, salivary glands, and sebaceous/oil glands.

Fibers

- Fibers provide different tensile properties, giving essential strength and support to connective tissue and providing anchorage to their cellular components. - There are three main types of fibers found in the extracellular matrix of connective tissue, as follows. - Collagen fibers: These are strong and flexible, and often occur in parallel bundles, providing strength to tissue and thus enabling it to resist pulling forces. Collagen fibers are made up of the protein collagen, found in plentiful supply throughout the body. Most tissues contain collagen fibers, the properties of which vary, depending on the tissue. There are more than 20 types of collagen, which combine to produce different morphological forms, with different functional properties. For example, cartilage collagen fibers have a high affinity for water, giving it cushioning properties. - Elastic fibers: Elastic fibers are small in diameter and branch to form networks of strong, stretchable, interconnected fibers. The main component of elastic fibers is the protein elastin, which assembles into filaments and sheets by cross-linking. Elastin is strengthened and stabilized by microfibrils of the glycoprotein fibrillin. Elasticity, the ability to return to its original shape after being stretched, is a unique property of elastic fibers, making it an important component of tissues that make up structures such as the skin, blood vessels, and lungs. - Reticular fibers: Reticular fibers are very fine, and branch to form strong, supportive frameworks. Reticular fibers, produced by fibroblasts, are made up of the protein collagen, and are strengthened and stabilized by a glycoprotein coating. They are present in blood vessel walls, areolar connective tissue, adipose tissue, smooth muscle tissue, and soft organs, such as the spleen and lymph nodes.

Fibrocartilage

- Fibrocartilage is made up of thick bundles of collagen fibers, interspersed with chondrocytes in their lacunae. It resembles dense regular connective tissue histologically, except that fibrocartilage has chondrocytes present in lacunae. It is the strongest cartilage in the body, providing strength and rigidity. - Fibrocartilage is a major constituent of intervertebral discs, tendon attachmentto bones, and the junctions between flat bones of the pelvis. It is also present in the menisci of the knee. It lacks a perichondrium.

Cell reproduction

- For humans, cell division in other than sex cells, produces two cells that are diploid. Division of the nucleus is called mitosis and division of the cytoplasm is called cytokinesis. - In the cells forming eggs and sperm, cell division will produce haploid cells by a process of nuclear division called meiosis. - The time a cell spends between two mitoses is called interphase and interphase is divided into three periods.

Medulla

- Formed by two or three layers of irregularly shaped cells, located in the center of a hair.

Glandular epithelium

- Glands are of two general types: a. Exocrine glands - secrete fluids outside the body via ducts such as saliva, mucus, earwax, oil, milk and digestive enzymes. b. Endocrine glands - have no ducts, secrete substances called hormones directly into the blood. Examples include the thyroid, pituitary and adrenal glands. - Membranes - mucous membranes line cavities of digestive, respiratory and reproductive systems. Serous membranes line the thoracic cavities and enclose heart and lungs. - How are epithelial cells held together? - Three structures help: a. Tight Junctions - form points of adhesion between lining cells to prevent leakage of molecules from outside to inside the body. b. Desmosomes or adhering junctions and Gap Junctions - desmosomes are spotlike welds holding cells together and gap junctions are protein tunnels connecting cytoplasms of two different cells.

Adhesion proteins

- Ground substance also contains adhesion proteins, which join all of the components of ground substance together, and attach them to the cells located within the connective tissue. One such protein is fibronectin, a multifunctional glycoprotein associated with collagen fibers, heparin, and other adhesion molecules.

Ground substance

- Ground substance is the fluid, semi-fluid, gelatinous, or calcified substance present in connective tissue found between the fibers and cells. Ground substance binds cells and gives them support, and also provides an area for the storage of water. The composition of the ground substance is a key determinant of the rate of diffusion of substances through extracellular matrix. A key component of ground substance is glycosaminoglycans (GAG). - GlycosaminoglycansGAG is a generic term for a variety of polysaccharides that trap water and affect the consistency of the ground substance. Most GAG molecules are attached to a protein core, forming large proteoglycans molecules. - GAG molecules include the following.

Hair

- Hair grows from the depths of the dermis but has its origins in the epidermis. It consists primarily of dead, keratinizedepithelial cells, connected by extracellular proteins. It has many functions: it protects from UV damage, advertises sexual maturity, and retains heat. It also has a sensory role. - A hair can be divided into anatomical regions: the shaft, the root, and the bulb.

Holocrine

- Holocrine glands secrete their products by shedding whole cells. Their product accumulates in the cytosol of the secreting cell until it matures, ruptures, and dies, becoming part of the secretion itself. The dead cell is sloughed off and replaced via cell division. - Sebaceous/oil glands are examples of holocrine glands

Mechanisms of homeostasis

- Homeostasis - means "staying the same" and refers to all the mechanisms the body uses to maintain the extracellular fluid in a physiological range for temperature, pressure, salt content, nutrient level. - Homeostatic Components - sensory receptors, stimulus, integrator and effectors. - Control of homeostasis can be by negative or positive feedback mechanisms. - Negative Feedback Mechanism - keeps body functions within a normal range by having end product inhibit or cancel stimulus that started the response. - Positive Feedback Mechanism - end result of stimulus is to increase response to further intensify output. Example - during childbirth, pressure of fetus on uterine walls stimulates production of oxytocin which further causes more pressure on fetus by increasing contraction. Process continues until fetus is expelled.

Hyaline cartilage

- Hyaline cartilage is composed of fine collagen fibers bound together by a resilient, gel-like ground substance. Together, these comprise the extracellular matrix. Prominent chondrocytes sitting in lacunae are found throughout the cartilage. It is the weakest but the most abundant cartilage in the body, providing flexibility and support, reducing friction, and absorbing shock. - Hyaline cartilage forms a temporary skeleton in the fetus, which is then gradually ossified (replaced by bone) during fetal growth and throughout the growth of the child, on into puberty. It also forms the epiphyseal plates of growing long bones, covers the articular surfaces of joints, and provides supportto respiratory passages. Hyaline cartilage is usually covered by perichondrium, except in the case of epiphyseal plates and joint articular surfaces.

Hyaluronic acid

- Hyaluronic acid is viscous and slime-like. Its functions include influencingcell migration, lubrication of joints, and stabilization of the eyeball. Hyaluronic acid is broken down into a more liquid substance by the enzyme hyaluronidase , which is produced by sperm, white blood cells, and some bacteria. Hyaluronidase promotes the movement and spread of such cells through connective tissue.

Interstitial growth

- Interstitial growth occurs from within the body of cartilage during childhood and adolescence, while cartilage is young and pliable. Existing chondrocytes within the cartilage increase in number through rapid cell division. The numerous chondrocytes synthesize and deposit an increasing amount of extracellular matrix. This pushes the chondrocytes away from each other, and the cartilage expands from within to increase in size.

Introduction: Integumentary system

- Introduction: The integumentary system is an organ system that includes the skin and its accessory structures, including the nails, hair, and sweat glands. The skin is the largest organ in the body and accounts for 15% of a person's body weight. The skin protects our bodies from trauma, acts as a barrier to bacteria and viruses, protects us from UV rays, secretes waste products, protects underlying tissue against fluid loss, stores lipids, produces vitamin D, and regulates body temperature. It also senses touch, pressure, and heat. - Protection: The skin forms a very effective chemical, biological, and physical barrier. - Thermoregulation: The skin plays a significant role in regulating body temperature as 80% of heat is lost through the skin. - Cutaneous sensation: There are a number of sensations that arise from the skin in a process known as cutaneous sensation. These include touch, pressure, vibration, tickle, temperature, and pain. - Excretion: Metabolic waste products can be excreted from the body in small quantities via sweat - Absorption: Many lipid-soluble substances can enter the body via the skin. - Vitamin D synthesis: The synthesis of vitamin D starts in the skin, triggered by ultraviolet light.

Keratan sulfate

- Keratan sulfate is present in bone, cartilage, and the cornea. It has cushioning properties for the absorption of mechanical shock.

Cortex

- Layers of elongated cells surrounding the medulla, forming a significant part of the hair structure.

Liquid connective tissue

- Liquid connective tissue consists of cells suspended within a liquid matrix. There are two types of liquid connective tissue within the body: blood tissue and lymph. - Blood: Blood tissue flows in blood vessels around the body. It consists of red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes) which are all formed in red bone marrow. These cellular components of the blood are suspended in a pale yellow liquid extracellular matrix known as blood plasma. Blood plasma consists of mainly water and salts and a variety of other dissolved substances, including proteins, nutrients (glucose and amino acids), and wastes (urea, uric acid, carbon dioxide). - Lymph: Lymph flows in lymphatic vessels around the body. It consists of several types of cells suspended in a clear liquid extracellular matrix, similar to blood plasma, but lacking some of the protein. Lymph varies in composition depending on the tissue it is draining.

Loose connective tissue

- Loose connective tissue consists of loosely arranged fibers that form a network between cells. - A number of types of loose connective tissue exist: - Areolar connective tissue: Areolar connective tissue is widely distributed throughout the body. It contains collagen, elastic, and reticular fibers, randomly arranged between cells. A range of cell types are present including fibroblasts, adipocytes, mast cells, macrophages, and plasma cells. Hyaluronic acid, chondroitin sulfate, dermatan sulfate, and keratin sulfate make up the ground substance in between the fibers and cells. - Areolar connective tissue is a delicate, thin, but highly vascularized tissue typically found deep to epithelial tissues. Its blood supply provides nourishment to and collects wastes from the avascular epithelia. Areolar connective tissue and adipose tissue make up the subcutaneous tissue deep to the skin. - Adipose tissue: Adipose tissue is widely distributed throughout the body. It is primarily composed of adipocytes, as well as fibroblasts and macrophages. As adipose tissue is well vascularized, capillary endothelium is usually visible histologically. Regions of adipose tissue may be divided into discrete compartments by fibrous septa. - Adipocytes contain triglycerides, stored as a single, large, centrally located lipid droplet, which pushes the nucleus and cytoplasm to the periphery of each cell. Adipose tissue functions as an insulator, an energy reserve, and supports and protects various organs. Adipose tissue is found alongside areolar connective tissue, making up the subcutaneous tissue deep within the skin. - Most adipose tissue is classed as white adipose tissue (unilocular adipose tissue). However, brown adipose tissue(multilocular adipose tissue) also exists, gaining its darker color from its rich blood supply and numerous mitochondria. Brown adipose tissue is present mainly in the fetus and in infancy, becoming extremely sparse in adulthood. Its function is to metabolize fat to produce heat for the maintenance of body temperature in the newborn - Reticular connective tissue: Reticular connective tissue is mainly made up of reticular fibers and reticular cells. It is present in smooth muscle, and also forms the supporting framework (stroma) of soft organs, such as the liver, spleen, and lymph nodes. The reticular cells within the framework of the reticular connective tissue act as filters in the spleen and lymph nodes, removing unwanted substances from the blood and lymph, respectively.

Melanocytes

- Melanocytes produce melanin granules, which contain the pigment melanin. Melanin absorbs UV radiation thereby protecting the skin from damage, and is also partly responsible for hair color - The hair follicle is innervated by a plexus of nerves that relay sensory information from the hair to the brain. - Also associated with each hair follicle is an arrector pili muscle

Membranes

- Membranes are thin sheets of tissue that cover and line structures throughout the body. They primarily function as protective surfaces and barriers. There are two main types of membrane: epithelial membraneand synovial membrane.

Merkel disc

- Merkel discs are slowly adapting touch receptors, also known as tactile discs or type I cutaneous mechanoreceptors. They are flattened, saucer-shaped free nerve endings that connect to Merkel cells. - Found in abundance in the fingertips, hands, lips, and external genitals.

Merocrine

- Merocrine glands are the most common type of exocrine gland. Secretory vesicles containing the cell product collect at the apical surface of the secretory cell, to be released via exocytosis into the lumen of the gland. - Salivary glands , sweat glands, and pancreatic acinar glands are examples of merocrine glands.

The microscope

- Microscopes are essential in histology for the observation and analysis of components of biological specimens not visible to the human eye. There are two main types of microscopes: the light (optical) microscope and the electron microscope.

Mucous membranes

- Mucous membranes are found lining body cavities, or tracts, that open into the external environment, such as the digestive, respiratory, andreproductive tracts. - The epithelial layer acts as a barrier, protecting the body against microbes and other pathogens. Mucous cells in the epithelial layer, for example goblet cells, secrete a thick, sticky, protein-rich fluid called mucus which prevents cavities/tracts from drying out, provides lubrication, and traps foreign particles. Secretory epithelial cells secrete enzymes and other cells play a role in absorption. - The type of epithelium present in mucous membranes varies with the location and functional purposes of the membrane. For example, the major epithelial type found lining the digestive tract is simple columnar epithelium with microvilli, whereas ciliated pseudostratified epithelium is the main type of epithelium found lining the respiratory tract. - The connective tissue layer (lamina propria) is made up of areolar connective tissue, which gives mucous membranes flexibility, while also supporting the overlying epithelium and anchoring it to underlying structures. Diffusion of oxygen, nutrients, carbon dioxide, and waste occurs across the lamina propria.

Structural classification of multicellular exocrine glands

- Multicellular glands may be classified structurally, according to the shape of their glandular portion and whether their ducts are branched or unbranched. - Simple glands have unbranched ducts, whereas compound glands have branched ducts. The secretory, glandular portion of a multicellular gland may be described as tubular if it is elongated or acinar (alveolar) if it is rounded. A gland is tubuloacinar if it has tubular and rounded portions. - The main types of multicellular exocrine glands are: - Simple straight tubular: These glands have a straight, glandular portion, with a single unbranched duct. - They are present in the crypts of the small intestine. - Simple branched tubular: These glands have a branching, tubular glandular portion, with a single unbranched duct. - Examples include the gastric glands. - Simple coiled tubular: These glands have a coiled, glandular portion, with a single unbranched duct. - Examples include sweat glands. - Simple acinar: These glands have a rounded, glandular portion, with a single unbranched duct. - Examples include the paraurethral glands in the penile urethra. - Simple branched acinar: These glands have a branched, glandular portion, with a single unbranched duct. - Examples include the sebaceous glands. - Compound tubular: These glands have a tubular, glandular portion, with a branched duct. - Examples include the bulbourethral glands(Cowper's glands) andBrunner's glands in the duodenum. - Compound acinar: These glands have a rounded, glandular portion, with a branched duct. - Examples include the mammary glands and the parotid salivary glands. - Compound tubuloacinar: These glands have both tubular and rounded portions, with a branched duct. - Examples include the pancreatic acinar glands, and the sublingual and submandibular salivary glands

Muscle tissue

- Muscle tissue has the unique property of being able to move, when the cells contract. Three types of muscle tissue can be distinguished: skeletal musclethat permits movement of the body, cardiac muscle that moves the blood around the vasculature, and smooth muscle that, amongst other things, facilitates the movement of food along the alimentary canal.

Muscle tissue

- Muscle tissue is a specialized tissue with both contractile and conductingproperties. It is made up of cells called muscle fibers, also known as myocytes or myofibers, derived from myocyte progenitor cells. Through the consumption of ATP and the conduction of action potentials, myocytes contract to produce movement, maintain posture, and generate heat. - Although the details differ for the different types of muscle, all muscle contraction is achieved through a sliding filament mechanism involving the repeated formation of crossbridges between the contractile proteins actin and myosin. For more information, see Muscular System: Physiology of Skeletal Muscle Fibers. - Muscle tissue is functionally classified as either voluntary (its contraction is consciously controlled), or involuntary (its contraction is not consciously controlled). It is also classified according to structural differences as either skeletal muscle tissue, cardiac muscle tissue, or smooth muscle tissue.

Nervous tissue

- Nervous tissue, especially in the brain, is highly complex. Histological examination of the arrangement of cells in nervous tissue gives some insight into the extraordinary range of functions that the brain is capable of.

Nociceptor

- Nociceptors are sensory neurons that are stimulated by extreme temperature, physical, mechanical or chemical irritation. They have bare nerve endings, and consist of two different types of axons: myelinated (fast) neurons and unmyelinated (slow) neurons - Found thoughout the body, except the brain, but most commonly in the skin and mucous membranes.

Neuroglia

- Non-neuronal cells called neuroglia are present in similar numbers to neurons in the human brain. They consist of a small cell body containing a nucleus and branching cytoplasmic processes, which vary in size and number. - There are many different types of neuroglia, such as astrocytes, each with varying functions but all with the ability to multiply and divide. They provide support, nourishment, and protection to the many neurons that constitute the nervous system. In addition, some glial cells enhance the transmission of action potentials by forming an insulating myelin sheath around the axons of neurons.

Important terms: DNA structure

- Nucleotide = [base]-[sugar]-[phosphate] - DNA bases = A, T, C & G - Sugar = deoxyribose

Pain

- Pain alerts the brain to potentially damaging sensations or actual tissue injury. It protects us from damage and also allows the body to repair. - The body contains special pain receptors called nociceptors. Upon tissue injury, certain chemicals are released, such as prostaglandins, kinins, and potassium ions. - The nociceptors can be broadly grouped into fast (A delta fiber) neurons or slow (C fiber) neurons. The fast pain neurons are myelinated and can conduct nerve signals at 30 meters a second. They are responsible for the 'acute pain' perceived at the time of injury. The slow pain neuronss are unmyelinated and can conduct nerve signals at 2 meters a second. They are responsible for the dull 'chronic pain' that follows an injury and that is associated with chronic diseases such as cancer and arthritis. - Nociceptors are unusual because they ordinarily only respond to a strong stimulus, however, following an injury they become increasingly sensitive (hyperalgesia). When tissues become injured or inflamed, they release chemicals such as histamine that cause the nociceptors to become much more sensitive. This means that the affected nociceptors will react to even a mild stimulus.

Paraffin wax embedding

- Paraffin wax embedding is the standard method for the preparation of finely sectioned specimens for histological analysis by microscopy. Paraffin wax fills the tissue, supporting all cellular components and resisting distortion during sectioning.

Sensation: Itch

- Receptor: Free nerve endings - Function: An itch is felt when free nerve endings are stimulated by specific chemicals. Bradykinin, a vasodilator produced in local inflammatory responses, can stimulate the free nerve endings and elicit such a response.

Sensation: vibration

- Receptor: Meissner's corpuscles - Function: Detect relatively low-frequency vibrations. - Receptor: Pacinian corpuscles - Function: Detect higher-frequency vibrations.

Sensation: Pressure

- Receptor: Meissner's corpuscles - Function: Detect stimuli, giving rise to the sensation of pressure. - Receptor: Pacinian corpuscles - Function: Detect stimuli, giving rise to the sensation of pressure. - Receptor: Merkel discs - Function: Detect stimuli, giving rise to the sensation of pressure.

Sensation: Touch

- Receptor: Meissner's corpuscles - Function: Sensitive to light touch, they rapidly adapt, therefore respond mainly at the onset of touch, signaling information about change in a stimulus. - Receptor: Merkel discs: - Function: Slow adapting receptors, they send signals as long as a stimulus persists. - Receptor: Hair root plexus - Function: Fast adapting receptors that detect movement to hairs.

Referred pain

- Referred pain is a phenomenon that occurs when pain is felt in a different location to the site of the causative injury. It occurs because the nerves supplying the viscera and the skin converge as they enter the central nervous system. The brain deals with pain from the skin more often, and so often falsely interprets visceral pain as cutaneous. - For example, the nerves of T1-T5 receive pain from both the heart and the skin of the left chest and arm, and from here, the neurons follow the same path to the thalamus. Because of this, the brain may become confused about the location of the pain and assume it is coming from the chest and arm, rather than the heart

Introduction: cell biology Dr. K

- Robert Hooke in the 17th Century, was the first to use a microscope to see that a thin slice of cork was compartmentalized into "cellulae," a latin word for cells, because the microscopic view of cork reminded him - Hooke and other early microscopists developed the "cell theory" which includes the following tenets: - all organisms are composed of cells, including us. - the cell is the smallest unit having properties of life. - new cells arise from growth and division of other cells.

Sebaceous glands

- Sebaceous glands produce sebum, an oily secretion that prevents the hair and skin from becoming brittle and dry. They are flask-shaped glands located in the dermis. They are abundant throughout the body, but are absent on palms of the hands and soles of the feet. Where present, most of these glands open into hair follicles, however, some sebaceous glands, such as those around the lips, glans penis, labia minora, and tarsal glands of the eyelids, open directly onto the skin

Sensory receptors

- Sensory receptors distributed throughout the body enable us to make sense of stimuli from the internal and external environment by converting them into nerve impulses that are interpreted by the brain. - These receptors form part of the somatosensory system, with somatic sensation referring to stimulation from any sensory receptor in the skin, the subcutaneous layer, mucous membrane, muscles, tendons, joints, and inner ear. - The skin contains sensory receptors known as cutaneous receptors, which convey cutaneous somatic sensation arising from stimulation of the skin. The different types of cutaneous receptors are classified according to their structure, the type of stimuli they respond to, and the way in which they respond.

Serous membranes

- Serous membranes, also known as serosae, are found covering organs (visceral serous membrane) and lining body cavities (parietal serous membrane) that do not open into the external environment. - Anatomically, visceral and parietal serous membranes are continuous with each other. Due to the embryological development of the organs as they grow into body cavities, the visceral and serous membranes become folded so that they lie immediately adjacent to each other, separated by serous fluid. - One method of picturing this is to imagine a balloon with some water inside it. Now imagine pushing your fist into the side of that balloon. Your fist represents the organs as they develop. After doing this, you would now have three layers surrounding your fist. The first layer would be the balloon immediately touching your fist (visceral layer). The second layer would be the water inside the balloon (serous fluid) and the third layer would be the other side of the balloon (parietal layer). - Examples of this include the parietaland visceral pleura, which covers the thoracic cavity and lungs, the parietal and visceral pericardium, which covers the heart cavity and heart, and the parietal and visceral peritoneum, which covers the abdominal cavity and the abdomen. As with mucous membranes, each serous membrane is histologically divided into two layers: the epithelial layer, which consists of mesothelium (a simple squamous epithelium) with secretory cells that secrete a watery, serous fluid that lubricates the organs and cavity walls, reducing friction and surface tension, and the connective tissue layer, which is made up of areolar connective tissuethat supports the overlying epithelium, anchoring it to underlying structures.

Skeletal muscle

- Skeletal muscle tissue is made up of long, thin, cylindrical skeletal muscle fibers. These vary from 10-100 μm in diameter, and from millimeters to many centimeters in length, depending on their location. Individual skeletal muscle fibers lie parallel to one another, forming skeletal muscles that attach to bones and perform voluntary movement and maintenance of posture. - Skeletal muscle fibers are filled with contractile proteins arranged such that they form striations of alternating light and dark bands. The sarcoplasm (muscle fiber cytoplasm) also contains mitochondria and glycogen for energy production, a specialized smooth endoplasmic reticulum known as sarcoplasmic reticulum, and hundreds of nuclei located at the periphery of the cell, just deep to the sarcolemma(muscle fiber cell membrane).

Excretion

- Small quantities of metabolic waste products can leave the body via the skin. The body achieves this by regulating the volume and chemical composition of sweat. Water and salts can leave the body via the sweat glands, as can ammonia and urea, which are waste products resulting from the breakdown of protein. Carbon dioxide can also leave the body through the skin.

Smooth muscle

- Smooth muscle tissue is made of non-striated muscle fibers that are thickest in the center before tapering towards the ends. They have a central diameter of 3-8 μm and are 15-500 μm in length, depending on their location. They contain one, centrally located, cigar-shaped nucleus. They are often connected via gap junctions, promoting powerful, synchronized contraction. Smooth muscle tissue constitutes the walls of hollow internal structures, such as vessels, tracts, and organs. It enables involuntary visceral contraction, such as during vasoconstriction, which restricts blood flow, and peristalsis, which aids digestion and the elimination of waste from the body.

Spongy bone

- Spongy bone (also known as cancellousor trabecular bone) is found within the heads of long bones and throughout most irregular bones, such as those forming the ankle. It lacks the repeating osteons of compact bone, consisting instead of a network of fine, bony projections known as trabeculae. The trabeculae contain lamellae, osteocytes, lacunae, and canaliculi. Spongy bone is less dense than compact bone and the trabecular structure enables spongy bone to resist stress in many directions. - The intervening marrow spaces are usually filled with red bone marrow, where the cellular elements of the blood are formed during a process known as hemopoiesis. Yellow bone marrow may also be found within the marrow spaces of long bones. It is not present at birth, but red bone marrow is converted to yellow throughout childhood and until adulthood, by which time approximately half of all bone marrow is yellow.

Hypothermia

- Stimulus: Decrease in body temperature. - Receptor: Thermoreceptors in the skin, leading to increased stimulation of cold thermoreceptors and decreased stimulation of warm thermoreceptors. - Control center: Nerve impulses from the receptors are conveyed via sensory nerves to the thermoregulatory center in the hypothalamus. - Effectors: 1. 1. Blood vessels near the surface of the skin undergo vasoconstriction. In addition,arrector pili muscles in the skin contract, pulling the hair up perpendicular to the skin's surface. 2. Skeletal muscles undergo rapid contraction and relaxation, known as shivering. 3. The adrenal medulla increases the release of epinephrine and norepinephrine, which increase the basal metabolic rate. 4. The thyroid gland is activated, releasing the hormones T3 and T4, which also increase the basal metabolic rate - Response: These homeostatic mechanisms cause warming, thus body temperature returns to normal levels. As with most homeostatic mechanisms, this forms a negative feedback loop, with the response leading to a reduction in stimulus.

Hyperthermia

- Stimulus: Increase in body temperature. - Receptor: Thermoreceptors in the skin, leading to increased stimulation of warm thermoreceptors and decreased stimulation of cold thermoreceptors. - Control center: Nerve impulses from the receptors are conveyed via sensory nerves to the thermoregulatory center in the hypothalamus, which processes the information and sends out nerve impulses to the effectors. - Effectors: 1. Blood vessels near the surface of the skin undergo vasodilation. 2. Sweat glands of the skin produce increased volumes of sweat. - Response: These homeostatic mechanisms lead to cooling, thus body temperature returns to normal levels. As with most homeostatic mechanisms, this forms a negative feedback loop, with the response leading to a reduction in stimulus.

Quadrants of the abdomen

- The abdomen can be divided by two lines into four quadrants - The two lines that divide the abdomen into quadrants form a cross, the center of which is positioned over the umbilicus (belly button). These quadrants are often used to indicate the location of pain - The primal picture model is built from a real human specimen. This specimen has a u shaped transverse colon, a normal anatomical variation, which means that it does enter the lower left quadrant of the abdomen.

Arrector pili muscle

- The arrector pili (plural: arrectores pilorum) is formed by smooth muscle cells which extend from the hair follicle to the papillary layer of the dermis. Innervated by the autonomic nervous system, they cause the hair to stand on end in what is commonly known as 'goose bumps'. This action has a major role in thermoregulation for animals with thick fur, but in humans it of minor importance. - Growth of the hair occurs in cycles, which consist of a growth stage, regression stage, and resting stage.

Bulb

- The bulb is an onion-shaped structure deep in the dermis, where cell growth occurs. - A frontal section through a hair reveals a complex internal structure. The shaft is composed of three layers of cells, the medulla, cortex, and cuticle, arranged in concentric rings. These extend into the root and bulb.

Layers of the epidermis

- The cells of the epidermis are arranged into four or five layers which rest on a basement membrane. - Stratum corneum: The most superficial layer of the epidermis, consisting of 20-30 layers of dead keratinocytes. These dead cells have lost their organelles and have become keratinized. Glycolipids present in this layer help waterproof the skin and prevent water loss. - The stratum corneum resists friction and protects the rest of the skin from physical damage. This layer is especially thick over the soles of the feet and palms of the hands. - Stratum lucidum: Only found in the hairless, thick skin of the fingertips, palms and soles of the feet, the stratum lucidum is an additional layer appearing between the stratum granulosum and corneum. It consists of three to five layers of flat, dead keratinocytes. The cells appear clear and have thickened plasma membranes. - Stratum granulosum: Consists of three to five layers of mature keratinocytes. Mature keratinocytes produce two types of granules: keratohyalin granules (keratin producing) and lamellar granules. The latter contains water-resistant glycolipids which stick cells together and which are responsible for the waterproof properties of skin. - As mature keratinocytes close to the stratum their keratin content increases. In addition, they start to die, mainly due to insufficient nutrition as they move further from the capillaries which supply the skin. - Stratum spinosum: Consists of eight to ten layers of living keratinocytes joined together by desmosomal connections. Langerhans cells, epidermal dendritic cells, and melanin granules are also present in this layer - Stratum basale: A single layer of cuboidal-shaped cells on a basal membrane. This layer contains stem cells, keratinocytes, and melanocytes. It is also sometimes called the stratum germinativum , due to its role in cell germination, i.e., new skin cells are produced at the basal membrane pushing the older cells towards the surface.

Dermis

- The dermis lies immediately beneath the epidermis and is much thicker. It is responsible for the elasticity and strength of skin, supplies the epidermis with nutrients, and plays an important role in thermoregulation. - It contains two types of fibers: collagen and elastic. Collagen fibers provide the skin with its tensile strength and resistance to stretching forces, while elastic fibers provide its recoil properties. - The dermis is much more complex than the epidermis, being composed of numerous cell types (including macrophages, fibroblasts, and adipocytes) containing several important structures of epidermal origin (such as hair follicles and sweat glands), and providing the nutritional requirements for the epidermal growth (via capillaries). - The dermis can be divided into two sub-layers: - Papillary region: The papillary region is composed of areolar connective tissue, and is formed by protrusions of the dermis into the epidermis, increasing the contact surface area. The interior of these protrusions contains capillary blood vessels that supply the nearby epidermis with oxygen and nutrients. This region also contains tactile receptors, known as Meissner's corpuscles. - The papillary region usually constitutes approximately 20% of the dermis. - Reticular region: The reticular region is composed of dense connective tissue containing thick bundles of collagen fibers which give the skin its strength. - The reticular region usually constitutes approximately 80% of the dermis.

Cells of the epidermis

- The epidermis is composed of four main types of cells: keratinocytes, melanocytes, Langerhans cells, and Merkel cells: - Keratinocytes: Approximately 90% of epidermal cells are keratinocytes. They produce a substance called keratin, which is a tough and fibrous protein that serves to protect the skin. Keratinocytes also produce lamellar granules, which release a water-repellent substance that helps waterproof the skin. - The structure of keratinocytes changes dramatically as they mature: they change from square-shaped cells to flat cells. Throughout their life they become engorged with keratin before eventually dying, losing all of their internal structures - Melanocytes: Melanocytes make up 8% of epidermal cells and produce melanin granules. Melanin absorbs UV radiation thereby protecting the skin from damage, and is also partly responsible for skin color. - Melanocytes have protrusions that transfer melanin granules to the keratinocytes. These granules surround the external side of the keratinocyte nucleus thus protecting it from harmful UV radiation. - Langerhans cells: The epidermis contains a small number of Langerhans cells. These cells are part of the immune system and can recognize foreign microbes, engulf and destroy them, and present their antigens to the immune system for further action. - Langerhans cells originate in the bone marrow before migrating to the epidermis - Merkel cells: Merkel cells, otherwise known as tactile cells, are found at the border between the epidermis and the dermal layer. They have small dendrites that protrude in between nearby keratinocytes in the stratum spinosum. - Each Merkel cell is associated with a sensory nerve ending, called a Merkel disc (or tactile disc), and together, they act as a slowly-adapting touch receptor.

Extracellular matrix

- The extracellular matrix is made up of fibers (fibrillar proteins) and a ground substance component. The composition of each different type of connective tissue is unique, giving it the properties it requires to function efficiently.

Neurons

- The human brain has around 100 billion neurons (nerve cells). Individual neurons are the functional units of the nervous system. Each neuron is composed of a cell body, containing one nucleus and giving off a number of short branches, known asdendrites, and a single thin projection from the cell body, known as an axon, which ends in one or more axon terminals. - A key feature of neurons is their ability to respond to a stimulus by converting it into an action potential (electrochemical signal). The action potential is propagated along the surface of the neuronal axon until it reaches an axon terminal, where it triggers the release of a neurotransmitter into a synapse (a small gap between the axon terminal and another neuron). Neurotransmitters can diffuse across this gap and stimulate the adjacent neuron, which in turn may transmit an action potential. This is the basis of neuronal communication. The activity of networksof communicating neurons leads to brain functions including sensation, thought, and memory. Neurons are also responsible for many other functions, including the control of skeletal muscle activity and glandular secretions.

Hypodermis

- The hypodermis (also known as the subcutaneous layer) is not classified as a skin layer as such and lies below the dermis. It is composed of connective tissue that contains fat, blood vessels, and sensory receptors. It functions as a protective cushion and an insulator.

Types of skin

- The layers of the skin are largely uniform throughout the body, although their thickness, the distribution of the hair and glands, and the vascularization and innervation of the layers do vary. There are two major types of skin: - Hairy skin: Skin with hair is commonly referred to as thin skin as it only has an epidermal thickness of 0.10 - 0.15 mm. - The epidermis lacks the strata lucidumlayer and both the strata spinosum and stratum corneum are very thin. - Epidermal ridges are also lacking due to poorly defined dermal papillae. Hairy skin has a dermal thickness of 1 - 2 mm. Within this layer, sebaceous glands are present, but sudoriferous glands and sensory receptors are sparsely distributed. - Non-hairy skin: Skin without hair has a much thicker epidermis (0.6 - 1.5 mm) than hairy skin: the stratum lucidum, spinosum, and corneum are much thicker. For this reason, hairless skin is often called thick skin. - Epidermal ridges (whorling patterns not seen in skin that has hair) are present, as dermal papillae are abundant and organized into parallel rows. Hairless skin can have a dermal thickness of 3mm. Hair follicles and sebaceous glands are absent, whereas sudoriferous glands and sensory receptors are abundant.

Choose the action of the buccinator muscle. 1. keeps food from collecting between teeth and cheeks 2. closes eye as in winking 3. raises the upper eyelid 4. raises the upper lip as in smiling 5. closing and pursing the lips

1. keeps food from collecting between teeth and cheeks

Nail

- The nail is a clear plate of dead keratinized epidermal cells that covers and protects the dorsal aspect of the finger tips and toes. It can be described as follows: - Plate: The nail plate is the translucent, visible portion of the fingernail and lies dorsally at the distal end of the digit, overlying the nail bed. It can be described in three separate parts: - Root: The proximal end of the nail, which lies beneath the skin and extends several millimeters into the finger. - Body: The main portion of the nail that overlies the nail bed. - Free edge: The distal overhang of nail plate over the pulp of the digit. - Bed: Also known as the sterile matrix, it is a type of connective tissue that lies beneath the nail plate. It adds material (in the form of keratin) just below the nail, making it thicker and stronger as it grows forwards. - Lunule: The white, half-moon-shaped area at the proximal end of the nail. - Matrix: Also known as the germinal matrix, it is the layer of keratinocytes that surround the nail root. A major part of active nail growth takes place in this region. - Hyponychium: Underneath the free edge of the nail is an area called the hyponychium, or nail bed, which is a thickened area of skin made from the stratum corneum. It serves to secure the nail to the fingertip.

pH Values

- The pH Scale is a measure of the hydrogen ion concentration in a solution such as blood, water or orange juice. - Most acid solution starts at a pH of 0 such as HCl. - Neutral solutions such as pure water are at pH 7.0 - Most basic solution is NaOH at at pH 14. - The normal pH of human blood ranges from 7.35 - 7.45 and the normal ph inside cells ranges from 7.0 - 7.2. Stomach acid has a pH from 1.0 - 3.0. - Normal rain water has a pH around 5.5, slightly acidic. Acid rain may have a pH as low as 3.0. - Why does normal rain water have a lower pH than pure water at a pH of 7.0?( Answer? )

Membrane structure and function

- The plasma membrane (cell membrane) is formed of a lipid bilayer (two rows) - The primary lipid in the cell membrane is the phospholipid which has a hydrophobic and hydrophilic side so that when the phospholipids form a bilayer membrane, the hydrophilic (water loving) side faces out and the hydrophobic (water fearing) side faces inward. See the graphic of a lipid bilayer and note that the hydrophobic sides of the phospholipids face inward and are arranged as far away as possible from the water molecules and the hydrophilic end faces the water molecules.

Shaft and root

- The shaft is the region of hair extending beyond the epidermis. The root is the region of hair which penetrates into the dermis, deep to the shaft.

Protection

- The skin forms a very effective chemical, biological, and physical barrier. The following substances help provide protection: - Keratin: The layers of keratinized stratified squamous epithelium form a physical barrier against pathogens, and protect deeper tissue against abrasion and heat - Sweat: Sweat is secreted onto the skin regularly. It is relatively acidic and salty, both of which help inhibit microbial growth - Defensins: Epithelial cells produce cationic proteins called defensins which have antimicrobial properties and help prevent the colonization of the skin. - Langerhans cells: Epidermal Langerhans cells alert the body to pathogens while dermal macrophages engulf viruses and bacteria that have managed to pass thus far. - Glycolipids: Glycolipids and the oily secretions of the sebaceous glands prevent both the absorption of water into the skin, and excessive evaporation of water from the skin. - Melanin: Melanin absorbs ultraviolet (UV) radiation to protect deeper tissue from damage. - Normal flora: Some non-pathogenic micro-organisms grow on the epidermal surface, which helps prevent colonization by other pathogenic microbes.

General functions of the skin

- The skin plays a significant role in homeostasis: it protects our bodies from trauma, acts as a barrier to bacteria and viruses, protects us from UV rays, senses touch, pressure, and heat, controls water levels, secretes waste products, produces vitamin D, and regulates body temperature.

Vitamin D synthesis

- The synthesis of vitamin D starts in the skin. When ultraviolet light penetrates the skin, it converts 7-dehydrocholesterol into cholecalciferol, which is then transported in the blood to the liver and kidneys for further processing into calcitriol, which is a biologically active form of vitamin D. - Among other functions, calcitriol helps to regulate the level of calcium in the blood.

Which vertebral type has the largest body? 1. lumbar 2. cervical 3. sacral 4. coccygeal 5. thoracic

1. lumbar

Thermoregulation

- The temperature of the body must remain roughly constant at 98.6 oF (37 oC) in order for the underlying biochemical reactions that control the body to proceed at optimal conditions. - Hyperthermia occurs when body temperature rises above the normal level, whereas hypothermia occurs when body temperature drops below normal. If either of these states occurs, under normal conditions the body is able to activate a variety of homeostatic mechanisms which correct the temperature change and return body temperature to normal levels. Disease states or severe atmospheric conditions however, can overwhelm the homeostatic mechanisms, leading to prolonged or extreme hyper- or hypothermia, which can be fatal. - In order to maintain homeostasis of body temperature, any heat produced by the body must equal any heat that is lost. Heat is produced throughout the body as a byproduct of chemical reactions and 80% of heat loss occurs through the skin through a number of physical processes.

Histology images

- The thumbnail below shows a photomicrograph of a section of skin from a finger tip. Note the dermis and the major strata of the epithelium, especially the keratinized stratum corneum at the apical surface.

Histology images

- The thumbnail below shows the histology of a sebaceous gland. Note the distribution about the hair follicle. - The thumbnail below shows the histology of a sweat gland. Note the simple tubular structure of the ducts.

Cutaneous sensation

- There are a number of sensations that arise from the skin such as touch, pressure, vibration, tickle, temperature, and pain. This is known as cutaneous sensation. The detection of these different stimuli and subsequent processing have different functions. - Many different and specialized nerve endings are required to detect such a diverse array of sensations

Interactive learning

- There are four types of somatic sensation: tactile sensation, thermoreception, pain, and proprioception. Cutaneous somatic sensation only arises from stimulation of the skin and therefore only includes tactile sensation, thermoreception, and pain. Proprioception provides information about the relative position of body parts and movement, conveyed from proprioceptors located within joints, muscles, tendons, and the inner ear.

Anatomical planes

- There are three major anatomical planes: axial, coronal, and sagittal - Axial (transverse or horizontal) plane: - This plane cuts the body horizontally, into superior (upper) and inferior (lower) portions - Coronal (frontal) plane: - This plane cuts the body vertically, into anterior (front) and posterior (back) portions - Sagittal plane: - This plane cuts the body vertically down the midline, into equal left and right portions. Any deviation from this line and the plane is referred to as a parasagittal plane.

Skin color

- There are three pigments that contribute towards skin color: melanin, hemoglobin, and carotene - Melanin: Melanin is produced by melanocytes, which are located in the stratum basale of the epidermis. Melanin helps to protect the skin and underlying tissue from harmful UV radiation. These cells are most abundant in the penis, nipples, areolae, face, and limbs, but can also be found in mucous membranes. - The number of melanocyte cells is approximately the same throughout the human race. However, the amount of pigment that each melanocyte produces varies. Melanin may accumulate in certain areas producing freckles, or age spots, and a nevus (mole) can develop due to a benign, localized overgrowth of melanocytes. - Melanocytes produce the enzyme tyrosinase, which converts tyrosine into melanin. Enzymatic activity in the melanozome, the organelle where melanin is produced, increases upon exposure to UV radiation. Thus, increased exposure to sunlight produces increased melanin production and a darker skin appearance. Two types of melanin are produced, pheomelanin, which has a pink to red color, and eumelanin, which varies in color from yellow to brown to black. The type and amount of melanin produced influences the final skin color of an individual. - Hemoglobin: Hemoglobin is the oxygen-carrying molecule in red blood cells. When oxygenated, hemoglobin appears red. In light skinned individuals, the translucent epidermis lacks significant quantities of melanin, meaning that the skin appears pink to red, depending on the oxygen content of blood in the underlying capillaries. - Carotene: Carotene, found in many sources of food, is a precursor to Vitamin A and produces a yellow to orange color. It is stored in the stratum corneum and the fatty areas of the dermis and subcutaneous layers. Upon excessive consumption of carotene, the skin can appear orange. - In evolutionary terms, skin color is predominantly dictated by a trade-off between two factors: allowing sufficient levels of ultraviolet light into the skin necessary for the synthesis of vitamin D, while also preventing excessive damage caused by these same rays. Therefore, different ethnic groups will have sufficient melanin concentrations that reduce ultraviolet damage, without compromising the ability to produce vitamin D.

Skin glands

- There are three types of glands found in the skin: 1. Sebaceous glands, which secrete sebum to soften the skin and hair. 2. Sweat glands, which secrete salt and water as sweat, the evaporation of which helps to lower body temperature 3. Ceruminous glands, which secrete cerumen in the external ear, protecting, lubricating, and cleaning it.

Which part of the temporal bone has a large prominence for the insertion of the sternocleidomastoid muscles? 1. mastoid process 2. squamous part 3. tympanic part 4. petrous part

1. mastoid process

Connective tissue classification

- There are two major subclasses of connective tissue: embryonic connective tissue, present in the embryo through its development into a fetus, and mature connective tissue, present in the newborn through its development into adulthood and beyond. - Embryonic connective tissue includes mesenchyme, found almost exclusively in the embryo and from which all other connective tissues are derived, and mucous connective tissue, a form of mesenchyme found in the umbilical cord of the fetus. - Mature connective tissue includes loose connective tissue, dense connective tissue, cartilage, bone, and liquid connective tissue. In addition, they all have their individual subtypes.

Sweat (sudoriferous) glands

- There are two types of sweat glands: merocrine and apocrine. They consist of simple, coiled tubes embedded in the dermis or hypodermis, and they open either into the hair follicles or directly onto the skin's surface. Sweat differs in composition between merocrine and apocrine glands. - Sensible perspiration is when sweat is secreted and forms a visible layer, whereas insensible perspiration is when sweat is secreted, but evaporates before a visible layer is formed. - Merocrine glands: Also known as eccrine glands, these are the more abundant of the two types of sweat glands and are found all over the skin. High concentrations are found on the palms of the hands and soles of the feet. A merocrine gland consists of a twisted tube located within the dermis, which opens directly onto the surface of the skin as a sweat pore - Sweat from merocrine glands contains water, and a range of other components, including ions, urea, uric acid, ammonia, amino acids, and lactic acid. - Merocrine glands are activated by the sympathetic nervous system in response to hyperthermia. The evaporation of the resultant increase in sweat leads to cooling of the body. Merocrine glands can also release sweat due to emotional stress. Fear or embarrassment for example, can lead to emotional sweating or to what is commonly known as 'a cold sweat'. - Apocrine glands: Apocrine glands are large sweat glands that develop during puberty, and are mainly located in the armpits and anogenital areas. In addition, mammary glands within the breast are considered to be a specialized type of modified apocrine sweat gland. - The secretory part of the gland is located in the dermis and the duct opens into a hair follicle. Apocrine glands produce a viscous, off-white secretion that contains many of the substances found in merocrine sweat plus additional fatty organic compounds. Bacteria break down these organic compounds to produce a characteristic odor sometimes referred to as body odor. - Unlike merocrine glands, apocrine glands do not contribute to thermoregulation, but may be activated in response to emotional stress. - The term apocrine gland is known to be something of a misnomer. It was originally thought that the cells comprising these glands secreted their products by pinching off a section of the cell containing these products, which is known as apocrine secretion. However, it is now known that these cells secrete their product by endocytosis, which is known as merocrine secretion. To avoid potential confusion the term apocrine gland has been retained.

Regression stage

- This stage, commonly called the catagen stage occurs when the cells in the hair matrix stop dividing, preventing further growth. The hair follicle then shrinks. This stage usually takes 2 to 3 weeks.

Thermoreception

- Throughout the skin, thermoreceptors, consisting of free nerve endings, detect temperature. They have a receptive field of about 1mm in diameter on the skin's surface. Thermoreceptors adapt quickly to a stimulus, but also continue to generate impulses at a lower frequency upon continued stimulation. - Receptor: Cold receptors - Function: Cold receptors can be found in the stratum basale layer of the epidermis. Most cold receptors are attached to medium-diameter, myelinated A fibers, however, some are attached to small-diameter, unmyelinated C fibers. The receptors are stimulated by temperatures between 50°F (10°C) and 105°F (40°C). - Temperatures below 50°F stimulate pain receptors. - Receptor: Warm receptors - Function: Warm receptors are found in the dermis, connected to small-diameter, unmyelinated C fibers. These receptors are stimulated by temperatures between 90°F (32°C) and 118°F (48°C). - Temperatures above 118°F stimulate pain receptors.

Skin wound healing

- When damage to the skin occurs, a healing process is initiated in order to repair the structure of the skin and return its original function. Epidermal wound healing takes place when only the epidermis has been penetrated, whereas deep wound healingtakes place when the dermis has been penetrated.

Evaporation

- When sweat is secreted onto the surface of the skin, the sweat absorbs heat from the skin and evaporates, effectively taking heat away from the body. This is particularly effective in hot climates as it is the only way that heat can be lost from the skin. However, in humid climates, when there is already a lot of water present in the air, heat loss through sweating and subsequent evaporation is diminished.

Papilla of the hair

- Within the bulb is an indentation called the papilla, which contains blood vessels and connective areolar tissue

What anatomic feature is represented and able to be palpated in the region of the medial or inner portion of one's ankle? 1. medial malleolus 2. medial condyle 3. anterior border 4. tibial tuberosity 5. lateral condyle

1. medial malleolus

Which movement about a synovial joint describes twisting the foot so that the sole faces inward toward the center line of the body? 1. inversion 2. protraction 3. adduction 4. pronation 5. abduction 6. retraction

1. inversion

Choose the correct classification for muscle contraction which involves no change in length or tension. 1. isometric contraction 2. eccentric isotonic contraction 3. concentric isotonic contraction 4. isotonic contraction

1. isometric contraction

Which of the following statements best describes what happens during the initial phase of muscle contraction. 1. Creatine phosphate passes phosphate quickly to ADP to make more ATP 2. glucose and fatty acids delivered from bloodstream provides source of energy for ATP production. 3. glycolysis will begin and accumulate ATP and lactic acid until muscle contraction ceases due to cramping 4. aerobic respiration of glucose from glycogen (stored in muscle) generates needed ATP

1. Creatine phosphate passes phosphate quickly to ADP to make more ATP

What is the name for the cup-shaped depression on the side of the hip formed by the ilium, ischium and pubis? 1. acetabulum 2. iliac crest 3. ischial tuberosity 4. anterior superior iliac crest 5. obturator foramen

1. acetabulum

Two proteins, troponin and tropomyosin, are found along the surface of the __________ filaments. 1. actin 2. cross bridges 3. calcium ions 4. myosin

1. actin

Aerobic exercise works muscles at a rate at which the body can keep them supplied with oxygen and results in what changes in the muscles being exercised? 1. all of the above 2. there is an increase in size and number of mitochondria 3. muscle tissues contain more of the oxygen-binding pigment myoglobin. 4. the number of blood capillaries in the muscle increases

1. all of the above

Skeletal muscle contraction requires ___________. 1. all of the above 2. arrival of a nerve impulse 3. ATP 4. calcium ions

1. all of the above

The function of amphiarthroses can be best described by which one of the following? 1. allows a small degree of movement 2. provides no movement 3. allows free movement

1. allows a small degree of movement

What happened to the body portion of the atlas (C1 vertebra)? 1. became attached to axis (C2) body to form dens 2. became attached to occipital condyles 3. disappeared during the fetal maturation process 4. became attached to the first thoracic

1. became attached to axis (C2) body to form dens

Choose the correct order for the stages of bone remodeling? 1. bone resting, bone resorption, bone reversal, bone formation, bone mineralization 2. bone reversal, bone formation, bone mineralization, bone resting, bone resorption 3. bone resorption, bone reversal, bone formation, bone mineralization, bone resting 4. bone formation, bone mineralization, bone resting, bone resorption, bone reversal

1. bone resting, bone resorption, bone reversal, bone formation, bone mineralization

Which one of the following ions is released into the cytosol of muscle fibers in response to an action potential and plays a key role in skeletal muscle contraction? 1. calcium 2. potassium 3. sodium 4. phosphate 5. chloride

1. calcium

What is the insertion for the diaphragm? 1. central tendon 2. lumbar part of L1 - L3 3.xiphoid process of sternum 4. costal part of ribs 1 - 6

1. central tendon

Which movement about a synovial joint describes lifting the scapula upwards? 1. elevation 2. extension 3. depression 4. flexion 5. plantar flexion 6. dorsiflexion

1. elevation

Which one of the following terms describes the sheet of thick connective tissue that surrounds the entirety of a skeletal muscle? 1. epimysium 2. perimysium 3. hypomysium 4. automysium 5. endomysium

1. epimysium

Which one of the following is the term used to describe the ability of a muscle to stretch without injury? 1. extensibility 2. contractility 3. excitability 4. convertibility 5. elasticity

1. extensibility

Which one of the following muscle groups acts to increase the size of the throrax by drawing the ribs upwards and outwards? 1. external intercostals 2. diaphragm 3. internal intercostals 4. innermost intercostals 5. transverse abdominis

1. external intercostals

What muscle forms the outermost layer of the sidewalls of the abdomen? 1. external oblique 2. internal oblique 3. transversus abdominis 4. rectus abdominis

1. external oblique

Which terms below best describe the joints that become the sutures in the skull? 1. fibrous and synarthroses 2. cartilaginous and amphiarthroses 3. synovial and diarthroses 4. synovial and synarthroses 5. fibrous and diarthroses

1. fibrous and synarthroses

Which one of the following bony features is best described as a small pit or depression that provides attachment for muscles and ligaments? 1. fovea 2. trochanter 3. crest 4. eminence 5. spine

1. fovea

Which one of the following types of fracture occurs when one bone is forcefully driven into another, affecting both ends of the bone? 1. impacted 2. green stick 3. open 4. spiral 5. compression

1. impacted

Which one of the following rotator cuff muscles serves to extend the shoulder and laterally rotate the arm? 1. infraspinatus 2. supraspinatus 3. teres minor 4. subscapularis

1. infraspinatus

What is the insertion for the semispinalis capitis muscle? 1. spinous processes of T3 - T6 vertebra 2. C1 - C3 transverse processes 3. clavicle 4. scapula 5. transverse processes of T3 - T6 vertebra

2. C1 - C3 transverse processes

An elastic cartilage model of the long bone forms first 1. true 2. false

2. False

pick the term below that best describes what a foramen is. 1. an opening of a canal through a bone 2. a round hole through a bone 3. a bony groove that houses a tendon, nerve or blood vessel 4. a cavity or recess in a bone 5. a slit through a bone

2. a round hole through a bone

Which of the following statements best describes what happens in muscle fibers after 5 - 10 minutes of strenuous exercise. 1. glycolysis will begin and accumulate ATP and lactic acid until muscle contraction ceases due to cramping 2. aerobic respiration of glucose from glycogen (stored in muscle) generates needed ATP 3. Creatine phosphate passes phosphate quickly to ADP to make more ATP 4. glucose and fatty acids delivered from bloodstream provides source of energy for ATP production.

2. aerobic respiration of glucose from glycogen (stored in muscle) generates needed ATP

Which of the muscles listed below are involved in increasing intra-abdominal pressure in processes like coughing, urination, defecation, childbirth, vomiting and respiration? 1. internal oblique 2. all of the listed muscles 3. transverse abdominis 4. rectus abdominis 5. external oblique

2. all of the listed muscles

Identify the small triangular muscle on the lateral side of the elbow with an origin on the lateral epicondyle of the humerus, insertion on the olecranon of ulna and action of extending the elbow. 1. pronator quadratus 2. anconeus 3. flexor pollicis longus 4. brachioradialis 5. extensor digitorum

2. anconeus

As the electrical impulse spreads over the muscle fiber at the start of contraction, it causes the sarcoplasmic reticulum (smooth ER) in the muscle fiber to release _____________ ions. 1. potassium 2. calcium 3. sodium 4. phosphate

2. calcium

Which one of the following terms best describes the shortening of a muscle while maintaining constant tension within that muscle? 1. eccentric isotonic contraction 2. concentric isotonic contraction 3. isometric contraction

2. concentric isotonic contraction

When the diaphragm contracts, what happens to the air pressure inside the thoracic cavity? 1. stays the same 2. decreases 3. increases

2. decreases

Which one of the following muscles is multipennate? 1. omohyoid 2. deltoid 3. triceps brachii 4. pronator quadratus 5. rectis femoris

2. deltoid

Which movement about a synovial joint describes moving the foot to close the angle between the foot and the leg? 1. flexion 2. dorsiflexion 3. plantar flexion 4. extension 5. depression 6. elevation

2. dorsiflexion

The epiglottis is an example of which one of the following types of cartilage? 1. fibrocartilage 2. elastic cartilage 3. hyaline cartilage

2. elastic cartilage

Which muscle below is located on the anterior forearm and divides into four tendons which insert on fingers 2 - 5 and act to extend the wrist and fingers 2 - 5? 1. pronator quadratus 2. extensor digitorum 3. ancones 4. flexor pollicis longus 5. brachioradialis

2. extensor digitorum

All of each I band is contained within a sarcomere. 1. true 2. false

2. false

Along the bottom edge of the internal oblique, a tunnel is formed for passage of the round ligament in females. 1. true 2. false

2. false

At the cellular level, the loss of bone as we age is due to osteoclasts producing more bone than osteoblasts breakdown. 1. true 2. false

2. false

Bones are not considered organs because they do not contain the four basic tissue type 1. true 2. false

2. false

Cardiac muscles can only contract if they are stimulated by nerves or by artificial means. 1. true 2. false

2. false

Epiphyseal plate formation is the first step in long bone formation . 1. true 2. false

2. false

In muscle contraction, the actin ""head"" contains an enzyme, ATPase, which breaks down ATP to ratchet (move) the myosin filament forward as long as ATP is present. 1. true 2. false

2. false

Muscles composed of thousands of muscle fibers follow the all or none principle for contraction. 1. true 2. false

2. false

The all or none principle for muscle fiber contraction means that all the muscle fibers of a muscle contract or none do when the muscle is stimulated to contract. 1. true 2. false

2. false

The axial skeleton consists of the bones of the skull, pectoral girdle, rib cage, and vertebral column. 1. true 2. false

2. false

The diploe of flat bones is typified by the presence of a diaphysis, epiphysis and medullary cavity. 1. true 2. false

2. false

The insertion of the biceps is the scapula. 1. true 2. false

2. false

The intervertebral foramen is the opening between the pedicles which allow for the passage of the spinal cord and meninges 1. true 2. false

2. false

Pick the description that best fits the term "spine" as in the anterior superior iliac spine. 1. an elevation or projection 2. a narrow ridge of bone 3. a sharp, pointed, narrow process 4. a small pit or depression 5. a rough projection of bone for attachment of muscles 6. a small, rounded projection 7. a shallow, broad or elongated pit

3. a sharp, pointed, narrow process

Pick the description that best fits the term "fovea" as in the fovea of the head. 1. a shallow, broad or elongated pit 2. an elevation or projection 3. a small pit or depression 4. a narrow ridge of bone 5. a rough projection of bone for attachment of muscle 6. a sharp, pointed, narrow process 7. a small, rounded projection

3. a small pit or depression

Muscles that act to move a limb away from the midline of the body commonly have which one of the following terms as part of their name? 1. extensor 2. levator 3. abductor 4. adductor 5. pronator

3. abductor

In movements possible around a synovial joint, __________ describes the movement of an arm or leg being moved closer to the body. 1. hyperextension 2. flexion 3. adduction 4. extension 5. abduction 6. circumduction

3. adduction

The combination of a Haversian Canal, concentric lamellae (rings around canal) and osteocytes is called what? 1. Haversian System 2. osteon 3. all of the above

3. all of the above

Pick the description that best fits the term "eminence" as in the intercondylar eminence. 1. a shallow, broad or elongated pit 2. a small, rounded projection 3. an elevation or projection 4. a narrow ridge of bone 5. a sharp, pointed, narrow process 6. a small pit or depression 7. a rough projection of bone for attachment of muscles

3. an elevation or projection

in a joint, cartilage fills the space between bones resulting in not much movement such as with breastbone (sternum) and some ribs 1. synovial 2. fibrous 3. cartilaginous

3. cartilaginous

In which one of the following stages of a twitch contraction does crossbridge formation occur? 1. latent period 2. relaxation period 3. contraction period

3. contraction period

Which one of the following is not one of the common properties associated with all muscles? 1. extensibility 2. electrical excitement 3. convertibility 4. contractility 5. elasticity

3. convertibility

What is the action of the temporalis muscle? 1. keeps food from collecting between teeth and cheeks 2. raises the upper lip as in smiling 3. elevates and retracts the mandible 4. closes eye as in winking 5. closing and pursing the lips

3. elevates and retracts the mandible

This bone is a single bone in the midline of the cranium and contains air cells and the cribiform plate. 1. sphenoid 2. temporal (tympanic part) 3. ethmoid 4. occipital 5. frontal

3. ethmoid

In movements possible around a synovial joint, __________ describes the movement which causes the angle between two bones to widen. 1. circumduction 2. flexion 3. extension 4. hyperextension 5. abduction 6. adduction

3. extension

Which one of the following best describes the action of the triceps brachii? 1. flexion of the elbow and shoulder 2. adduction and medial rotation of the humerus 3. extension of the elbow and adduction of the arm 4. flexion of the shoulder and adduction of the arm 5. supination of the forearm

3. extension of the elbow and adduction of the arm

Which of the thorax muscles below are most active during inspiration (breathing in)? 1. internal intercostals 2. innermost intercostals 3. external intercostals

3. external intercostals

What bone forms the bump or lateral malleolus located on the lateral side of the ankle? 1. talus 2. calcaneus 3. fibula 4. tibia

3. fibula

What is the action of the iliacus and psoas major muscles of the hip? 1. flexing the leg 2. extending the hip and trunk 3. flexing and abducting the hip and flexing the trunk 4. extending the leg

3. flexing and abducting the hip and flexing the trunk

Which thin muscle of the posterior forearm forms into four thin tendons distally with an origin on the common flexor tendon, insertion on middle phalanges 2 - 5 and action of flexing fingers 2 - 5? 1. pronator teres 2. brachioradialis 3. flexor digitorum superficialis 4. flexor digitorum profundus 5. flexor pollicis longus

3. flexor digitorum superficialis

Choose from the options below the correct order for the stages of intramembranous ossification. 1. calcification of the osteoid matrix, formation of trabeculae, development of the periosteum, formation of an ossification center 2. development of the periosteum, formation of an ossification center, calcification of the osteoid matrix, formation of trabeculae 3. formation of an ossification center, calcification of the osteoid matrix, formation of trabeculae, development of the periosteum 4. formation of trabeculae, development of the periosteum, formation of an ossification center, calcification of the osteoid matrix

3. formation of an ossification center, calcification of the osteoid matrix, formation of trabeculae, development of the periosteum

The roof of the orbits along with the supercilliary arch are regions of what bone? 1. sphenoid 2. ethmoid 3. frontal 4. temporal (tympanic part) 5. occipital

3. frontal

pick the description that best fits the term "fossa" as in the iliac fossa. 1. a rough projection of bone for attachment of muscle 2. a small pit or depression 3. an elevation or projection 4. a shallow, broad or elongated pit 5. a sharp, pointed, narrow process 6. a narrow ridge of bone 7. a small, rounded projection

4. a shallow, broad or elongated pit

Which of the hamstring muscles below have an origin on the ischial tuberosity? 1. semitendinosus 2. biceps femoris 3. semimembranosus 4. all do 5. none do

4. all do

In a healthy knee, what structure(s) does the synovial fluid come in contact with? 1. articular cartilage 2. articular capsule 3. articular fat pad 4. all of the listed options

4. all of the listed options

Starting from the point at which ATP binds to the heads of the myosin filaments, place the following in the correct sequence to describe the muscle contraction cycle 1. crossbridge formation, ATP hydrolysis, crossbridge detachment, power stroke 2. crossbridge formation, power stroke, crossbridge detachment, ATP hydrolysis 3. crossbridge detachment, ATP hydrolysis, crossbridge formation, power stroke 4. ATP hydrolysis, crossbridge formation, power stroke, crossbridge detachment

4. ATP hydrolysis, crossbridge formation, power stroke, crossbridge detachment

Pick the description that best fits the term "crest" as in the iliac crest 1. a small pit or depression 2. a small, rounded projection 3. a sharp, pointed, narrow process 4. a narrow ridge of bone 5. an elevation or projection 6. a shallow, broad or elongated pit 7. a rough projection of bone for attachment of muscles

4. a narrow ridge of bone

Which thin muscle below is located on the front of the forearm with origin on the humerus, insertion on the styloid process of radius and flexes the elbow. 1. anconeus 2. pronator quadratus 3. flexor pollicis longus 4. extensor digitorum 5. brachioradialis

5. brachioradialis

Choose the action of the orbicularis oris muscle. 1. closes eye as in winking 2. raises the upper lip as in smiling 3. raises the upper eyelid 4. keeps food from collecting between teeth and cheeks 5. closing and pursing the lips

5. closing and pursing the lips

In order to regulate the levels of calcium in the blood, which one of the following hormones is secreted by the thyroid gland and opposes the effects of parathyroid hormones by reducing osteoclastic activity in bone? 1. insulin-like growth hormone 2. thyroid hormone T3 3. human growth hormone 4. calcitriol 5. calcitonin

5. calcitonin

pick the term below that best fits what a sulcus is. 1. a round hole through a bone 2. a cavity or recess in a bone 3. an opening of a canal through a bone 4. a slit through a bone 5. a bony groove that houses a tendon, nerve or blood vessel

5. a bony groove that houses a tendon, nerve or blood vessel

pick the term below that best fits what a sinus is. 1. a bony groove that houses a tendon, nerve or blood vessel 2. a slit through a bone 3. a rounded hole through a bone 4. an opening of a canal through a bone 5. a cavity or recess in a bone

5. a cavity or recess in a bone

Which one of the following neurotransmitters is released by somatic motor neurons where they synapse with skeletal fibers? 1. glutamate 2. serotonin 3. dopamine 4. norepinephron 5. acetylcholine

5. acetylcholine

pick the term below that best fits what a meatus is. 1. a cavity or recess in a bone 2. a round hole through a bone 3. a slit through a bone 4. a bony groove that houses a tendon, nerve or blood vessel 5. an opening of a canal through a bone

5. an opening of a canal through a bone

what anatomic feature on the hip bone is injured when one has a hip pointer? 1. obturator foramen 2. acetabulum 3. ischial tuberosity 4. lateral condyle 5. anterior superior iliac crest 6. medial malleolus

5. anterior superior iliac crest

pick the description that best fits the term "tubercle" as in the lesser tubercle of the humerus 1. a narrow ridge of bone 2. a sharp, pointed, narrow process 3. an elevation or projection 4. a shallow, broad or elongated pit 5. a small pit or depression 6. a small, rounded projection 7. a rough projection of bone for attachment of muscle

6. a small, rounded projection

In movements possible around a synovial joint, __________ describes the spreading of one's fingers. 1. adduction 2. extension 3. hyperextension 4. cicrumduction 5. flexion 6. abduction

6. abduction

Which movement about a synovial joint describes bringing the fingers together? 1. abduction 2. pronation 3. protraction 4. supination 5. retraction 6. adduction

6. adduction

What is the origin of the coracobrachialis muscle in the shoulder? 1. infraspinous fossa of scapula 2. supraspinous fossa of scapula 3. subscapular fossa of scapula 4. inferior angle of scapula 5. lateral border of scapula 6. coracoid process of scapula

6. coracoid process of scapula

What is the action for the brachialis muscle? 1. extend the wrist 2. extend the elbow 3. extend the shoulder 4. flex the wrist 5. flex the shoulder 6. flex the elbow

6. flex the elbow

Which movement about a synovial joint describes the movement of rotating the forearm so that the palms face upwards or in the anterior direction? 1. retraction 2. protraction 3. adduction 4. abduction 5. pronation 6. supination

6. supination

which bone below forms the inferior and lateral walls of the orbits? 1. lacrimal 2. maxilla 3. nasal 4. hyoid 5. palatine 6. zygomatic 7. mandible

6. zygomatic

pick the description that best fits the term "tuberosity" as in the ischial tuberosity. 1. an elevation or projection 2. a sharp, pointed, narrow process 3. a shallow, broad or elongated pit 4. a small, rounded projection 5. a small pit or depression 6. a narrow ridge of bone 7. a rough projection of bone for attachment of muscle

7. a rough projection of bone for attachment of muscle

Impulse Conduction in a Neuron

A nerve impulse is an electrochemical event which enables a signal to be transmitted along a nerve axon or dendrite. The important electrical and chemical events which cause an impulse to be formed and conducted along an axon or dendrite follow: Neurons exhibit a constant membrane electrical potential termed a resting membrane potential, i.e., a separation of charge between the inside and outside of the external neuron cell membrane (positive charge outside, negative charge inside membrane). When nerve impulse conduction is stimulated, a change in electrical potential occurs termed the action potential, i.e, a reversal of charge on the outside surface from + to -. Electrical activity in cells is determined by the separation of sodium and potassium ions. (sodium ions tend to be present outside cells and potassium ions are located inside of cells). During impulse conduction, channel proteins permit sodium ions to rush into neurons and potassium ions to leak out. (See in online text - click on Nervous System, Action Potentials, then read Depolarization phase.) All cells possess a resting potential but neurons also posses an action potential which is how the nerve impulse is conducted. Action Potentials Neuron membranes exhibit an electrical threshold for stimulation, i.e., if the stimulus is not high enough or strong enough, no electrical impulse or action potential occurs. When threshold is reached, action potential spike is an "all or nothing" event. No partial action potentials exist! The action potential and nerve impulse are examples of positive feedback. As sodium ions rush into cell membrane at specific site, they cause nearby membrane areas to be permeable to sodium also causing a nerve impulse to travel or be conducted down the nerve axon or dendrite.

Chemical Synapse

A neuromuscular synapse (see in Nervous System, Synapses, Synapses and Neurotrnasmitters) is a place where one neuron may stimulate another neuron or muscle cell by secreting neurotransmitters across a small space termed the synaptic cleft. The neurotransmitters then bind to receptors on the postsynaptic cell membrane to cause sodium ions to flow in and cause an action potential Acetylcholine or Ach is a neurotransmitter secreted by neurons to stimulate other neurons and also muscles to contract. In the disease, myasthemia gravis, Ach receptors are destroyed causing muscle weakness and fatigue. A synapse between a neuron and a muscle is termed a neuromuscular junction. An enzyme, acetylcholine esterase, destroys Ach in the synaptic cleft to stop stimulus response and is a way to control chemical transmission of nerve impulse because as long as Ach is in synaptic cleft, nerve transmission or muscle contraction will occur. Neuromodulators may modify the effect of neurotransmitters. Endorphins, for example, are highly effective pain killers and are secreted by the body during intense physical activityandcan produce what is known as the "runner's high", after one "hits the wall". Reflex Arcs - sensory and motor neurons sometimes take part in reflex reactions such as the reflex reaction involved with stretch receptors in muscles. (See Nervous System, Reflexes, Reflex Arc - also check out video clip) Another example is the patellar tendon reflex (the knee jerk when the tendon below the patella is tapped lightly).

Stress Response

Any change in the external environment that pushes on our body's homeostatic balance is considered stress. Stressors are the stimuli that can cause stress. Stressors might be just a change in external temperature or the sense of fear from being in danger. Eustress is considered "good stress" which can actually enhance the functional ability of the body but most of us are familiar with distress which is, for example, how our body responds to a "fight or flight" situation. Hormones of the Stress Response" The hypothalamus is the region of the brain that coordinates the three stages of the stress response, the first of which follows Fight or flight response The hypothalamus responds to any stress that appears to place the body in danger by sending nerve impulses to the sympathetic division of the autonomic nervous system. Epinephrine is released by the adrenal medulla which then causes the following stress responses. dilation of airways glycogen is converted to glucose increased heart rate and strength of contraction constriction of blood vessels in the viscera and in the skin reduction of blood flow to kidneys which results in increase of blood pressure increase in sweating Resistance Reaction This is the endocrine response which prolongs the stress response and the hormones causing this are listed below Corticotropin-releasing hormone: secreted by anterior pituitary gland and stimulates release of cortisol from the adrenal cortex. Growth-hormone-releasing hormone: stimulates release of human growth hormone from anterior pituitary gland which stimulates secretion of insulin-like growth factors by the liver. Thyrtropin-releasing hormone: stimulates release of thyroid-stimulating hormone from the anterior pituitary which stimulates secretion of thyroid hormones Stress Responses Cortisol stimulate lipolysis, gluconeogenesis and protein catabolism. Insulin-like growth factors also stimulate lipolysis and glycogenolysis (glycogen to glucose) Thyroid hormones stimulate ATP production from glucose to supply extra ATP to cells metabolically active during the stress response. Exhaustion Stress resistance by the body lasts until the body uses up all its resources and suffers from exhaustion. Chronic exposure to long term stress causes negative effects such as muscle wasting, pancreatic beta cell failure and immune suppression.

MUSCLES OF THE ARM

Biceps brachii - large muscle located on front of the arm. It has two heads that merge into a single thick tendon. It has a two-fold origin with the long head attaching to the scapula and the short head attaching to the coracoid process of the scapula, insertion on the radial tuberosity of the radius and action that flexes the elbow and shoulder, abducts the arm and supinates the forearm. Triceps brachii - large muscle on back of arm which has three heads that merges into a single tendon. Origin of long head is on scapula and lateral and medial heads attach to humerus, insertion is on the olecranon of the ulna and the action is to extend the elbow and adducts the arm. Brachialis - passes in front of the elbow with origin on the humerus, insertion on the coracoidprocess of the ulna and action to flex the elbow.

Overview of Skeleton

Bone remodeling occurs during the first 20 or so years of life. Bones are organized into two major divisions: Axial Skeleton - bones of skull, rib cage, and vertebral column Appendicular Skeleton - bones of Pectoral Girdle (shoulder) and upper extremities (arms), bones of Pelvic Girdle and lower extremities (legs). Ligaments connect bone to bone at places called joints. Tendons connect muscles to bone or sometimes muscles to other muscles. Axial and Appendicular Skeleton (See Online Anatomy & Physiology text) Axial Skeleton The Skull - composed of bones that protect the brain, inner ear and eyes. Provide jaws for attachment of teeth. Bridge of nose only boney part, rest of nose is cartilage. Sinuses are air spaces in bones such as the temporal that lighten the skull. Sinusitus sometimes occurs when bacterial infections invade sinuses causing trapped air to expand with low pressure externally causing headaches and discomfort in bones surrounding eyes. Vertebral column protects spinal cord from base of skull to pelvic girdle. Intervertebral disks support each vertebra and may be herniated or ruptured when undue stress is placed on them. Soft gel-like core of a disk may pop through (herniate) and place pressure on spinal nerves in that area causing pain and discomfort. Ribs connect to sternum to offer protection to lungs and heart.

Growth and Maintenance of Skeleton

Bones grow and change shape as the fetus grows and as the child grows after birth. Osteoblastsare involved in making new bone and osteoclasts are involved in bone resorption that is called bone remodeling. Note that the osteoclast does just the opposite of the osteoblast in that it resorbs bone (dissolves bone) while the osteoblast lays down new bone.

Mechanism of Remodeling (Shaping of Bone)

Calcium and phosphate are two key minerals needed by the body and are stored in bone. Hormones from the parathyroid gland are involved in releasing calcium from bone and also in storing it in bone. When blood calcium level is low, PTH (parathyroid hormone) is released and stimulates osteoclasts to dissolve bone, releasing calcium. When blood calcium is high, calcitonin is released and stimulates osteoblasts to make new bone.

Cardiac Muscle

Cardiac muscle is similar to skeletal muscle in that it is also striated but differs in a number of ways: 1. Presence of intercalated disks (see online text) 2. Fibers are branched forming a 3-dimensional of fibers 3. Single nucleus located in the center of the fiber 4. In tissue culture, cardiac cells beat spontaneously and rhythmically 5. Cardiac muscle is involuntary Intercalated disks are junctions of two cardiac muscle cells that occur only at I Band. Desmosomes occur in intercalated disks to provide strong adhesive force, lack of calcium can cause desmosomes to break apart, separating two cardiac cells. Gap junctions are also in the intercalated disk region and provide easier connection for electrical activity to be transferred from one cardiac fiber to another by way of ion exchange. T-System in Cardiac Fibers Fine structure analysis has shown that T tubules of cardiac muscle differ from those in skeletal muscle in the following ways: 1. They are larger than those for skeletal muscle. 2. The T tubules are located at Z line rather than at the A-I junction as in skeletal muscle. 3. No large terminal cisternae are found in sarcoplasmic reticulum. 4. The protein-polysaccharide coat of muscle cell's sarcolemma is also found inside enlarged T tubules, indicating that T tubules are there to provide for larger surface area to exchange nutrient and waste products between, inside and outside of cell. It has been estimated that no point in a cardiac cell is more than 2-3 microns from the extracellular space, either at the cell surface or in one of the T tubules.

Cerebral Cortex Close-up Look

Cerebral cortex (see Nervous System, Brain Module, Brain topic on subject area list on left in online text) - grey matter (unmyelinated cell bodies of neurons) on outer surface of cerebrum. Consists of four lobes: Occipital Lobe - located at the lower rear portion of the cerebrum, visual centers are located here. It is ocated under the occipital bone of skull. Parietal Lobe - located on the upper rear of the cerebrum, it contains the the somatosensory cortex, and receives signals from skin and joints. Frontal Lobe - primary motor cortex, coordinates instructions for motor responses. Temporal Lobe - located behind the ears on the sides of each cerebral hemisphere, processes information about hearing and complex visual associations such as identifying faces. Sperry's Split Brain Experiments In an attempt to cure severe epilepsy, Sperry cut the corpus callosum which serves to conduct impulses from one cerebral hemisphere to the other. Experiments showed that these patients were left with two separate minds, i.e., with two cerebral hemispheres that were able to exhibit two separate types of experiences, each out of the realm of the other. To understand the basic experiment, you need to know about how the brain maps a visual image. The basic idea is that the right side of each eye is visualized by the left cerebral hemisphere and the left side of each eye is visualized by the right cerebral hemisphere. (See Nervous System, Cranial Nerves, Optic Nerve in online text for view of how optic nerve crosses over to feed visual data from eye to brain hemispheres.) Sperry's Experiment - Sperry performed an experiment on a person who had their corpus callosum cut so that no crossing over of visual information occurred in

Vertebra Types

Cervical Vertebra: C1 is the atlas (remember that in Greek mythology, the God Atlas supported the heavens on his shoulders). The atlas does not have a body and is shaped like a ring of bone that articulates with the occipital bone of the cranium. C2 is the Axis which has the body of the C1 vertebra fused to its body to form an upward projection called the dens and the Atlas vertebra rotates around the dens. This means that when you move your head from right to left or left to right as in signifying "no", your C1 atlas is articulating with the C2 axis but when you nod your head up and down as in meaning "Yes", you are now articulating the atlas with the occipital condyles of the occipital bone of the skull. The transverse process on the cervical vertebra has a transverse foramen for the passage of the vertebral arteries to the brain. Only the cervical vertebra have transverse foramen. Thoracic Vertebrae (12): form the vertebral column of the thorax and possess facets on their transverse process for articulation with the ribs. Only the thoracic vertebra possess rib articulation facets on their transverse process. Lumbar Vertebra: are the largest vertebra with the largest body portion of all the vertebra due to these vertebra forming the main focal point for the weight of the upper body. Sacrum and Coccyx: five sacral vertebra fuse to form a triangular sacrum and from 3 - 5 coccygealvertebra fuse to form the coccyx. The sacrum articulates laterally with the hip bones.

THE DIAPHRAGM

Diaphragm is a dome-shaped musculofibrous sheet dividing the thorax from the abdomen. I t has openings for the inferior vena cava, esophagus and aorta. Origin is on the xiphoid process of the sternum, costal part of ribs 6 - 12, lumbar part (bodies) of L1 - L3, insertion on central tendon and action of when contracted, the dome flattens and lowers the floor of the thorax increasing the size lowering the pressure in the thoracic cavity and external air then is drawn into the lungs.

Muscle Function

Each skeletal muscle fiber is filled with myofibrils composed of large polymers of actin and myosinfilaments. A myofibril is composed of large polymers of the contractile proteins, actin and myosin. Many myofibrils form one muscle cell. The contractile unit in a muscle myofibril is the sarcomereand many sarcomeres are lined up sequentially in a muscle myofibril. A sarcomere is the area formed between two Z-lines. If you understand what happens in one sarcomere, you can understand how the entire muscle contracts. See online A & P text in Unit Muscular System, Contraction section for contracted and relaxed sarcomere. In the contraction process, the z-lines of a sarcomere move closer together with the actin filaments sliding over the myosin filaments. The myosin molecules in the large filaments have cross-bridges that, with the action of ATP as the energy source, ratchet the actin filaments toward each other. *Refer to the Physiology section - Muscle Contraction Cycle of the Muscular System unit in the online A & P text. Note the following points about the "sliding filament" hypothesis of muscle contraction. In ATP hydrolysis, the myosin head comes closer to the actin filament with the ADP and remaining phosphate group is attached to the myosin filament. In Crossbridge Formation , the myosin heads now attach to the actin filaments to form crossbridges with the remaining phosphate group being released. In the Power Stroke phase, the myosin head tilts toward the center of the sarcomere, releases ADP and slides the actin filaments along with it. In the Detachment of Myosin from Actin phase, , the myosin "head" contains an enzyme, ATPase, which breaks down ATP to ratchet (move) the actin filament forward as long as ATP is present. The breakdown of ATP releases the myosin "head" from the actin to start the ratcheting process all over again to continue contraction cycle. In the myosin "head", the enzyme called ATPase breaks down ATP causing release of myosin from actin. Without ATP, myosin remains attached to actin and accounts for "rigor mortis", the hard contraction of muscles after death when no more ATP is being made. This means that ATP is actually needed to cause muscles to relax rather than to

MUSCLES INVOLVED IN RESPIRATION

External intercostals - fibers run obliquely from the bottom of one rib to the top of the adjacent rib. Origin - inferior borders of ribs 1 - 11, Insertion - superior borders of ribs 2 - 12 and action of increasing size of thorax by drawing ribs upwards and outwards and are most active during inspiration. Internal intercostals - lie between external and innermost muscles and run obliquely backwards from bottom of one rib to top of adjacent rib. Origin - inferior borders of ribs and costal cartilages 1 - 11, insertion - superior borders of ribs 2 - 12 with action of decreasing the size of the thorax by drawing ribs downwards and inwards and are most active during expiration. Innermost intercostals - origin on internal aspect of ribs 1 - 11, insertion on internal aspect of ribs 2 - 12 and action of stiffening the chest wall during respiration and are most active during expiration.

Classification of Skeletal Muscles

Fascicular Arrangement of Skeletal Muscles There are five categories of skeletal muscles that can be classified according to their fasciculararrangement. 1. Fusiform muscles - formed by a central muscle belly that converges at one or both ends into a tendon. Fusiform muscles can have one head at each end like the extensor carpi radialis longus. 2-headed muscle - fusiform muscle with two tendons that merge and insert into one like the biceps brachii. 3-headed muscle - a fusiform muscle with three tendons that merge and insert as one like the triceps brachii. 2. Parallel muscles - muscle fibers lie parallel to each other and form flat, straight, quadrateand 2-bellied muscles. Flat muscle - a parallel muscle that forms a sheet of fibers such as the transversusabdominis. Straight muscle - long and strap-like and may be interrupted by tendinous intersection such as the rectus abdominis. Quadratus muscle - composed of short fibers such as the pronator quadratus. 2-bellied muscle - muscle interrupted by a tendinous intersection such as the omohyoid. 3. Pennate muscles - muscle fibers are attached obliquely to a central tendon like the barbs of a feather. Unipennate muscle - has a central tendon to which fibers converge on both sides such as the rectus femoris. Multipennate muscle - has several tendons toward which muscle fibers converge such as the deltoid. 4. Orbicular muscles - sphincter-like sheet of muscle encircling an oriface such as the mouth or palpebral fissures. Example is the orbicularis oculi. 5. Convergent muscles - also known as triangular muscles, fibers originate from large area but converge onto one attachment point such as the temporalis.

CRANIAL BONES

Frontal Bone: from the coronal suture to the roof of the orbits with superciliary arch (curved ridge above the eyebrows). Frontal sinus (mucous membrane lined space) is above the nasal part of frontal bone. Occipital bone: forms back and base of skull and contains foramen magnum, large hole through which spinal cord leaves cranial cavity. You can feel the external occipital protuberance as a lump on the back of the skull which is the attachments site for the nuchal ligament. On the lateral part of the occipital bone are the occipital condyles which are the sites fro articulation with the superior facet of the atlas, the first cervical vertebra. Temporal bone: Squamous part - has zygomatic process for articulation with the zygomatic bone. Also has mandibular fossa for articulation with mandibular condyle. Temporal Bone: Tympanic part - external acoustic meatus is circular opening into auditory canal. Styloid process - narrow downward projection which serves as a site of attachment of the stylomandibular ligament stylohyoid and two other muscles. Temporal Bone: Mastoid Process - large prominence located behind external acoustic meatus and is the insertion point for the sternocleidomastoid muscle. Temporal Bone: Petrous part - has the Internal acoustic meatus in the posterior region for the vestibulocochlear nerve to go from the internal ear to the brain. Inside the petrous part, the inner ear contains the three bones known as ossicles, the malleus, incus and stapes for the transmission of sound from the tympanic membrane to the cochlea. Ethmoid Bone: single bone in midline containing air cells forming sinus-like cells draining int the nasal cavity and the cribiform plate which has many holes (olfactory foramina) for the olfactory nerves to carry sense of smell signals from nose epithelium to the olfactory bulbs in brain. Sphenoid: located at base of skull and shaped like a butterfly. Has many openings for nerves such as ophthalmic, oculomotor, trochlear and abducens nerves to reach the brain. The pituitary fossa is a deep pit on the superior surface and is shaped like a saddle for the pituitary to fit into and be protected.

Bones of the hand

Hand: consists of eight cmall, irregular carpal bones in the wrist, five metacarpal bones in the palm, three phalanges in the fingers and two phalanges in the thumb. Carpal bones consist of scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate and hamate. The scaphoid and pisiform are palpable (able to be felt). The scaphoid is located in the floor what is known as the anatomical snuff box at the base of the outstretched thumb. See Anatomic snuff box for location of snuff box region and reason for calling it "snuff box". Metacarpals: five miniature long bones that support the palm of the hand. Phalanges: fourteen miniature long bones of the digits.

GLUTEALS

Gluteal muscles are the three large muscles forming the buttocks and responsible for extension, abduction and lateral rotation of the hip joint. Gluteus maximus - large, quadrilateral mass of muscles that forms the shape of the buttocks with origin on posterolateral ilium of the hip, insertion on the gluteal tuberosity of the femur and action to extend and abduct the hip. Gluteus medius - large muscle of outer surface of ileum with origin on lateral surface of hip, insertion on the gluteal tuberosity and action to extend and abduct the hip. Gluteus medius - large muscle of the outer surface of the ilium with origin on lateral surface of the ilium of the hip, insertion on the greater trochanter of the femur and action to extend and abduct the hip.

Smooth Muscle

Individual smooth muscles have only one nucleus per cell and usually display a long slender form. Smooth muscle fibers normally are arranged in bundles such that the thick portion of the fiber lies alongside the thin portion of the next fibers. The myofibrils in smooth muscle are not arranged in as orderly a fashion as they are in striated or skeletal muscle so there is no noticeable striated appearance. Smooth muscles also contain many mitochondria located near the myofibrils to supply ATP for contraction. The myofibrils in smooth muscle are formed from many myofilaments and are made up of two contractile proteins, actin and myosin, as are the myofilaments in striated and cardiac muscle fibers. In areas where smooth muscle fibers are arranged in bundles, such as in the intestine, reticular fibers form a network which wraps itself around individual muscle fibers. These reticular fibers are embedded within a protein-polysaccharide material which appears similar to the basement membrane. Since these reticular fibers connect to the surrounding connective tissue, when the smooth muscle cells contract, the force of contraction is transmitted to the surrounding connective tissue enabling the entire tissue and organ to contract. Intermediate filaments are arranged inside the cell along the membrane in a crossing pattern such that when the myofibrils contract, they pull on the intermediate filaments and produce a shortened cell that has many bulges. At the light microscope level, when smooth muscle cells are fixed in the contracted state, their nuclei appear wavy. Smooth muscle in various parts of the body also differ in their physiological response to hormones such as seen with oxytocin and vasopressin (produced by the pituitary gland). 1. Oxytocin causes contraction of the smooth muscle of the uterus in terminal stages of pregnancy 2. Vasopressin causes contraction of smooth muscle surrounding walls of arterioles and can thus increase blood pressure This differential response to smooth muscle in different areas of the body to the same hormone indicates that the sarcolemma of smooth muscle cells in different parts of the body must differ with respect to their receptor molecules in the sarcolemma. Another characteristic of smooth muscle cells is that they will contract upon stretching. In the bladder, intestine or stomach, when a certain degree of distention occurs, the muscle fibers will contract, which in the case of the bladder can be distressing at times.

Classification of Skeletal Muscle Contractions

Isotonic contraction - muscle changes length but tension doesn't change. Concentric isotonic contraction - shortening a muscles but maintaining constant tension such as in lifting a glass from a table. Eccentric isotonic contraction - muscle lengthening occurs with constant tension such as lowering a glass back onto the table. Isometric contraction contraction - muscle does not change in length and tension doesn't change either. No movement occurs with this type of contraction and is used for bearing loads such as lifting a heavy object up in the air.

MUSCLES ACTING ON THE HUMERUS

Latissimus dorsi - muscle of the shoulder and shoulder girdle with origin on T7 - T12 spinousprocesses, iliac crest of hip bone and ribs 9 - 12, Insertion on humerus with action of extending, adducting and medially rotating arm at shoulder joint Pectoralis major - muscle of anterior chest wall that acts on shoulder joint with origin on medial end of scapula, sternum and costal cartilages 1 - 6, insertion on humerus and action of adducting and internally rotating the humerus, extending the should joint from a flexed position and flexes it from an extended position.

Characteristics of Bone

Let's focus first on the basic bone functions and bone structure. A primary function of bones is to form a framework for muscle attachment but bones also serve as organs and perform the following functions: Movement- with muscles attached to them, bones assist in maintaining or changing position of body parts. Protection- provide hard exterior compartment to house organs such as brain, lungs, heart and other organs. Support- bones support muscles and provide an attachment site for muscles Mineral Storage - bones serve as sites for storage of Calcium and Phosphate which can be released when body fluids require them. Blood Cell Formation- Some bones with spongy interiors serve as sites for blood cell formation. Bones vary in size from tiny ear bones to large femurs which make up the thigh bones. Bone shape can be categorized as (a) long , (b) short or cube-shaped and (c) irregular. Bones are organs in that they have all four basic tissue types in them, i.e, epithelium, connective tissue, muscle and nervous tissues. Bone is a living structure. Bone cells called osteocytes maintain structure of living bone in small compartments called lacunae. Terms to be familiar with from are: osteocyte - mature bone cell found in fully formed bone. They maintain bone and replace what is lost osteoblast - immature bone cell found in growing bone. They secrete bone matrix and can be found in areas of new bone formation. osteoclasts - are giant cells with up to 15 - 20 nuclei per cell. They function in bone resorption, i.e., shaping bone by resorbing bone in some areas. lacunae - small round spaces which house osteocytes compact bone - located in the shaft of long bones and appears solid but under the microscope has many lacunae with osteocytes in them as well as blood vessels to nourish the cells Haversian System (osteon) - the combination of a Haversian Canal, concentric lamellae(rings around canal) and osteocytes, Haversian Canal - space for blood vessel which brings nutrient to bone cells and takes waste products away Spongy Bone Tissue - found in the head of long bones and in the flat bones of the skull, contain red bone marrow and participate in red blood cell production red bone marrow - bone marrow in active formation of red blood cells and some types of white blood cells yellow bone marrow - bone marrow that has stopped producing blood cells and now is filled with fat tissue to give it a yellow color. How do long bones grow? First, a cartilage model of the bone is formed and then a bony collar forms around the future shaft area. Then blood vessels migrate into shaft area through boney collar and eventually two more areas of ossification occur at either end. An epiphyseal plate of cartilage forms at either end and is the future growth plate so bone may grow longer.

FACIAL BONES

Maxilla - paired bones forming much of the skeleton on the upper face and serve as site of support for teeth attachment. The palatine process extends horizontally to form most of the hard palate (what you can feel when you raise your tongue to touch the roof of the mouth cavity). It contains the maxillary sinus, the largest of the sinuses in our skull. Zygomatic Bone: forms the cheeks of the inferior and lateral walls of the orbit. Palatine Bone: forms part of palate at back of roof of mouth and also forms the floor of the orbit. Lacrimal Bone: paired bones which lie in the anterior part of the medial wall of orbit and contain the groove for the nasolacrimal duct known as the nasolacrimal canal. Fossa for lacrimal sac is a depression on lacrimal bone which collects tears from the eyes and empties into the nasal cavity. Nasal Bone: single bone that forms the upper part of the bridge of the nose. Inferior Nasal Concha: form lateral wall of nasal cavity and covered with mucous membrane. Vomer: flat bone forming lower part of nasal septum Mandible: largest movable bone in skull which forms the lower jaw with attachment of teeth. The coronoid process at the posterior portion is the site for attachment of the temporalis muscle which is what bulges out on the side of your jaw when your mouth is tightly clenched. Hyoid Bone: is a horseshoe-shaped bone located just superior to the larynx. It is the only bone that does not articulate with any other bone in the body and serves as the attachment site for muscles of tongue, pharynx and neck

MUSCLES OF THE LEG

Most leg muscles are involved in moving the ankle and toes. Muscles are also located in compartments but not all muscles or compartments will be covered here. Posterior Superficial Compartment Gastrocnemius - together with soleus, it forms the bulk of the calf musculature. It originates on the medial condyle (medial head) and lateral condyle (lateral head) of the femur, insertion on the calcaneus with action of flexing the knee and plantarflexes the ankle. Soleus - together with the gastrocnemius, it forms the Achilles tendon with origin on tibia and fibula, insertion on calcaneus and action to plantarflexes the ankle. Posterior Deep Compartment Popliteus - leg muscle acting on knee joint with origin on lateral condyle of femur, inserts on tibia and action is to rotate femur laterally. Flexor digitorum longus - becomes tendinous at back of ankle where it travels to sole of foot and divides into four tendons. Origin is the shaft of the tibia, inserts on the distal phalanges 2 - 5 with action to cause plantarflexion of the ankle and flexes the four lateral toes. Flexor halluncis longus - deep in calf, becomes tendinous at back of ankle and travels into sole of foot with origin on the shaft of fibula, insertion is on the distal phalanx of hallux and action is flexionof the big toe.

Neuron types

Motor Neurons - take information from the brain to muscles or glands; have many dendrites and one axon. Sensory Neurons - take information from receptors for heat, taste, touch, and light to the central nervous system (Brain and spinal cord). They have one axon and one dendrite. Interneurons - take information from one neuron to another neuron and reside entirely within the central nervous system. The rest of the cells in the nervous system are neuroglial cells to support and protect neurons. Some neuroglia can form layered coverings of neurons to enable faster impulse conduction. Other neuroglia can form macrophage cells which can phagocytose dead cells and invading microorganisms.

The Muscular System

Muscle cells in general have the common property of being able to contract (become shorter). Skeletal muscles contract in response to nervous stimulation but if the nerves are cut, the muscle will not contract unless stimulated artificially. Cardiac muscle responds to nervous stimulation to speed up or to slow down the contraction rate and if nerves are cut to the heart, muscle contraction still occurs. Cardiac muscle can contract on its own but needs nervous stimulation to increase or slow down heart rate. Smooth muscle contracts more slowly and responds to nervous stimulation and hormones.

Muscle Tension, Strength and Fatigue

Muscle tension is the collective force formed during contraction. A motor unit (see Contraction section of Muscular System in online A & P text.) is a motor neuron and all the muscle cells that it innervates and causes to contract. This means that one neuron innervates many skeletal muscle fibers and they all contract when that neuron stimulates them to contract. All or none principle for muscle fiber contraction - a threshold of stimulus activity must be reached before the muscle fiber will contract, but when it contracts, it does so with all its strength. Thus, a muscle (organ) exhibits graded contraction strength, i.e., the ability to contract strongly or weakly over a range of contraction strengths, by causing more and more muscle fibers (cells) to contract until all fibers are contracting and that is the limit of strength for that muscle. But, remember that each muscle fiber or cell (not muscle as an organ composed of thousands of muscle fibers or cells) contracts at its full strength or not at all, and a muscle fiber or cell does not exhibit graded muscle contraction

Skeletal Muscle Contraction

Muscles generate ATP in three ways: from creatine phosphate, anaerobic respiration and aerobic respiration. Creatine phosphate - creatine kinase transfers a phosphate from creatine phosphate to ADP making ATP. One ATP molecule is made from one molecule of creatine phosphate. There's usually enough creatine phosphate to supply for ATP for a sustained contraction of about 15 seconds so this type of energy source is used during short bursts of vigorous activity. The reverse process is used during muscle relaxation to make creatine phosphate. Anaerobic respiration - used when energy need of muscle is high and oxygen supply is low. Glucose produces ATP with production of pyruvic acid and then lactic acid which when it accumulates can eventually cause muscle cramping. Two molecules of ATP produced per glucose molecule through glycolysis. Aerobic cellular respiration - occurs when energy needs by muscle are not high and oxygenated myoglobin levels are high and muscle activity is low. Aerobic respiration releases 36 ATP molecules per glucose molecule but as soon as continued contraction occurs and oxygen levels and oxygenated myoglobin levels decrease, then respiration switches over to anaerobic. Muscle Fatigue - inability of muscle to maintain force of contraction caused by prolonged contraction and depletion of ATP, creatine phosphate, glycogen stores and oxygen with accumulation of ADP and lactic acid and a drop in muscle pH. Oxygen debt - increased muscle contraction builds up lactic acid and it takes time to replace ATP levels and remove lactic acid and the amount of oxygen necessary to do that is considered the oxygen debt.

MUSCLES OF THE HEAD

Muscles of Facial Expression - muscles that anchor skin to the skull and mandible and when contracted cause changes in facial expression. Scalp and Forehead: Occipitofrontalis: has two parts, one on forehead and the other on the back of the head which are joined together by an aponeurosis (broad sheet of fibrous tissue located on top of the head). Frontal belly of occipitofrontalis has its origin on the Galea aponeurotica, insertion on the skin of the forehead and its action is to raise the eyebrows and wrinkles the forehead. The occipital belly has its origin on the superior nuchal line of the occipitall bone, inserts of the Galea aponeurotica with an action of retracting the scalp (drawing it backwards). Ocular Region: Levator palpebrae superioris: thin muscle within upper eyelid and is the antagonist of the orbicularis oculi. Its origin is the lesser wing of the sphenoid, inserts on the superior tarsus (upper eyelid) and has an action of raising the upper eyelid. Orbicularis oculi: flat, circular muscle that surrounds the eye. It's origin is on the nasal part of frontal bone, frontal process and lacrimal bone with an insertion on the skin of the eyelid and action of closing the eye when you wink or squeeze your eyelid tight to keep out a foreign object. Oral Region: Orbicularis oris: circular muscle surrounding the mouth and lips with an origin on the Modiolus(concentration of fibrous tissue in cheek area for muscle attachment), insertion on the skin of the lips and action of closing and pursing the lips as after sucking on a lemon. Buccinator: sheet of muscle within the cheek with an origin on the maxilla and mandible, insertion on the Modiolus and action of compressing the cheek as in blowing up a balloon. It also aids in chewing by keeping the food from piling up between your teeth and cheeks. Zygomaticus minor: long, thin muscle of the cheek with an origin on the Zygomatic bone, insertion on the Oribularis oris and an action of raising the upper lip allowing us to smile and laugh. Platysma: Thin, flat, superficial muscle of the anterior neck with an origin on the superficial fascia of the thorax, insertion on the Mandible and Modiolus and action of wrinkling the skin of the neck which makes the Platysma the antagonist for the Zygomatic muscle You do not have to know this muscle but I am interested in knowing if you have Auricular muscles which have an action of wiggling the ears. I have them but not all people do. Many animals such as horses have them and are responsible for the twitching movement of their ears. If you can wiggle your ears, please let me know as I am curious as to how many people have auricular muscles.

Coordination of Movement

Muscles work together to produce a movement but usually one muscle may produce more of the movement than the others. The muscle doing the most for a movement is called the prime mover or agonist. Muscles that work in opposition to the prime mover and are known as antagonists. Prime mover (agonist) - muscle that is primarily responsible for a particular movement. Example is the triceps brachii being the prime mover in the extension movement at the elbow. Anatagonists - is the opposite of a prime mover and acts in opposition to the prime mover. An example is the biceps brachii being the antagonist to the triceps brachii and functions to flex the arm at the elbow. Synergists - a muscle that assists the prime mover by stabilizing and reducing any unwanted movement and acts to promote the same movement as that of the prime mover. An example is the brachialis as it works to flex the arm at the elbow and helps the biceps brachii to do this. Fixator - a muscle that holds the proximal end of another muscle, usually the prime mover, in place and helps the prime mover to act more efficiently. An example is the rotator cuff, latissimus dorsiand major pectoral muscles act together as fixators of the shoulder joint.

How solutes cross membranes

Neutral, small molecules get across but charged molecules do not cross membranes

MUSCLES ACTING ON THE SCAPULA

Pectoralis minor - muscle on anterior chest wall that acts on the scapula with origin on ribs 3 - 5, inserts on medial border and coracoid process of scapula with an action to pull the shoulder girdle forwards and downwards. Trapezius - large, triangular muscle on back of the neck, shoulders and upper back with origin on occipital bone, nuchal ligament and C7 - T2, insertion on clavicle and scapula and action of elevating and retracting the scapula (raises or lowers shoulders) and extending and laterally flexing the head and neck. Serratus anterior- side of thorax between ribs and scapula with origin on ribs 1 - 9, insertion on costal surface of medial border of scapula and action to protract (pull forward) the scapula and pectoral girdle. Action of trapezius, pectoralis minor and serratus anterior combines in throwing motion in which shoulder movers posteriorly, then forward and down.

Amino acids and proteins

Proteins are large polymers made of repeating amino acid subunits. There are 20 common amino acids. Example of structure.

Bones of the forearm

Radius: lateral bone of forearm (remember, arm is in anatomic position) which has several points of articulation. The Humeroradial joint with the capitulum of the humerus, the superior radioulnar joint with the radial notch of ulna, the middle radioulnar joint with the shaft of the ulna via the interosseous membrane and the radiocarpal joint with the scaphoid, lunate and triquetral bones of the carpal portion of the hand. Ulna: is the medial forearm bone and also has five articulations. The humeroulnar joint with the trochlea portion og humerus, the superior radioulnar joint with the head of the radius, the middle radioulnar joint with the shaft of the radius via the inteosseous memberane and the ulnocarpal joint with the carpal bones via the articular disc

ATP Formation and Levels of Exercise

Resting muscle cell has only a small amount of ATP ready for use in contraction. Creatinephosphate which is present in the muscle cells passes phosphate quickly to ADP to make more ATP during the initial phases of strenuous muscle contraction. After a while, aerobic respiration of glucose from glycogen (stored in muscle) generates needed ATP for 5 to 10 minutes. For the next half hour, glucose and fatty acids delivered from bloodstream provide a source of energy for ATP production. If strenuous muscle contraction continues and oxygen runs out, then glycolysis will begin and accumulate ATP and lactic acid until muscle contraction ceases due to cramping. Then oxygen debt is paid by rapid breathing to take in more oxygen quickly.

Types of Sensory Receptors

Sensory Receptors - microscopic structure There are three types of sensory receptors based on microscopic structure. Free nerve endings: formed by dendrites of sensory neurons and include sensory receptors for pain, heat, tickle, itch and touch. Encapsulated nerve endings: formed when dendrites are encased in connective tissue capsules such as those that detect pressure, vibration and touch. Specialized receptor cells: formed when individual cells form a synapse with sensory neurons such as receptors of special senses like rod and cone cells in retina, gustatory cells in taste buds and cochlea hair cells in inner ear. Sensory Receptors - location in body Exteroceptor: found near external body surface and pick up information about the external environment such as smell, taste, touch, vision and other environmental changes Interoceptor: in blood vessels, nervous tissue, muscles and visceral organs and provide information about internal environment. Proprioceptor: in joints, muscles, tendons and the inner ear and provide information about the relative position of body parts and movement. Sensory Receptors - type of stimulus modality Mechanoreceptor: stimulus is mechanical force such as touch, pressure, vibration and stretch. Thermoreceptor: change in temperature Photoreceptor: light is the stimulus Chemoreceptor: chemical stimulus Nociceptor: stimulated by chemicals released at the site of tissue damage Osmoreceptor: osmotic pressure It should also be noted that nerves are the organs of the nervous system.

MUSCLES OF THE SHOULDER

Shoulder is formed by the pectoral girdle and connects the upper limb to the axial skeleton. The rotator cuff is the name given to a complex of four muscles that orinate and insert into the greater and lesser tubercles of the humerus. The rotator cuff tendons blend with each other as well as the articular capsule of the shoulder joint to help reinforce it. The rotator cuff helps the shoulder to move and is also important to holding the head of the humerus within the glenoid cavity of the scapula. Supraspinatus - one of rotator cuff muscles, this thick muscle occupies the top of the scapula with an origin on the supraspinous fossa of the scapula, insertion on the greater tubercle of the humerus and action to abduct the arm Infraspinatus - one of rotator cuff muscles, this large, triangula muscle occupies back of the scapula with an origin on the infraspinous fossa of the scapula, insertion on the greater tubercle of the humerus and an action that extends and laterally rotates the arm Teres minor - one of the rotator cuff muscles, it is long and rectangular with an origin on the lateral border of the scapula, insertion on the greater tubercle of the humerus and adducts and laterally rotates the arm Subscapularis - one of four rotator cuff muscles, it is large, triangular muscle occupying the front of the scapula with an origin on the subscapular fossa of the scapula, insertion on the greater tubercle of the humerus with an action of adducting and laterally rotating the arm. Deltoid - thick, powerful muscle that covers the shoulder joint and upper humerus with an origin on the clavicle, spine of the scapula and acromion of the scapula, insertion on the deltoid tuberosity of the humerus and an action of abducting the shoulder. Teres major - forms part of the posterior wall of the axilla with the latissimus dorsi. It has an origin on the inferior angle of the scapula, inserts on the intertubercular groove of the humerus and has an action of extending the shoulder joint and adducts and medially rotates the humerus. Coracobrachialis - located on the front of the arm, its origin is on the coracoid process of the scapula, inserts on the humerus and has an action of flexing the shoulder and adducting the arm.

How Skeletal Muscles and Bones Interact

Skeletal muscles attach to bones at two sites which are referred to as the origin and insertion. Definition of Origin - during contraction, this end of the muscle stays relatively motionless. Definition of Insertion - during contraction, this end moves the most. Rule of thumb - the muscle insertion moves toward the origin Many muscles operate together to produce the same movement and are termed synergists while others work in the opposite direction and are termed antagonists. Example - biceps brachii (anterior portion of upper arm) can effect flexion of forearm onto upper arm. Triceps brachii (posterior region of upper arm) can effect extension by straightening forearm away from upper arm. Origin of biceps - scapula, insertion of biceps - radiusOrigin of triceps - scapula, insertion of triceps - ulna

MUSCLES INVOLVED IN MOVING HEAD AND NECK

Sternocleidmastoid - long, thick muscle located on the side of the neck with an origin on the clavicle and manubrium of sternum, insertion on the mastoid process of temporal bone and an action of flexing neck if both muscles act together or drawing head toward one shoulder if one acts individually. This muscle runs underneath the platysma. If the head is held in a fixed position, contraction of both sternocleidomastoid muscles raises the thorax and aids in forced inspiration (heavy breathing such as following exercise). You can palpate these muscles by pushing your chin up with your hand as you try to force your head down to your chest. Semispinalis capitis - a thin muscle of the posterior neck with an origin on the spinous processes of T3 - T6 vertebra, insertion on the C1 - C3 transverse processes and action of extending neck if both contract together and flexing and rotating the ehad if each muscle acts individually. MUSCLES OF THE TRUNK - contains muscles concerned with the movement of the vertebral coumn, respiration and control of intr-abdominal pressure. Muscles of the Abdomen - are important flexors of the vertebral column and responsible for increasing intra-abdominal pressure in processes like coughing, urination, defecation, childbirth, vomiting and respiration. Rectus abdominis - strap-like muscle on front of abdomen enclosed in rectus sheath with three tendinous insertions in each belly to form the "six pack". The origin is on the pubis of the hi bone, insertion is one the xiphoid process of the sternum and costal cartilages 5 - 7 and action whic flexes the vertebral column and increases intra-abdominal pressure External oblique - outer layer forming the sidewalls of the abdomen whose inferior border forms the inguinal ligament. The origin is on ribs 5 - 12 and the iliac crest of the hip bone, insertion is one the pubis of the hip bone and the linea alba and has an action to flex and rotate vertebral column and increases intra-abdominal pressure. Internal oblique - is the middle layers forming the sidewalls of the abdomen. Origin is one the thoracolumbar fascia, iliac crest of hip bone and the inguinal ligament, insertion on costal cartilages 9 - 12, line alba and xiphoid process of the sternum with an action of flexing and rotating the vertebral column and increases intra-abdominal pressure. Transversus abdominis- the innermost layer forming the sidewalls of the abdomen. Origin is lower costal cartilages, iliac crest of hip bone and inguinal ligament, insertion on costal cartilages 9 - 12, linea alba and xiphoid process of sternum with an action of flexing and rotating vertebral column and increases intra-abdominal pressure. Rectus sheath - tendons of abdominal muscles merge together at front of abdomen to form a fibrous sheath with a mid-portion known as the linea alba Inguinal ligament - forms along bottom edge of external oblique to create a tunnel which in females is the site for passage of the round ligaments of the uterus and in males the spermatic cord and other femoral vessels and nerves passing into the thigh.

Brain and Behavior

The Limbic System (see Nervous System, Brain, Limbic System in online text) is referred to as our emotional brain. The Limbic System is related evolutionarily to our olfactory or sense-of-smell region. That is why smells sometimes evoke many emotional responses andmemories. The Limbic System is composed of the thalamus, hypothalamus, amygdala and hippocampus. Raw emotions such as rage and hatred emanate from here but are controlled by linkage to the cerebral cortex. Other self-satisfying behavior such as eating, sex and other pleasure centers are also located in the limbic system. Functioning of the hypothalamus portion of the limbic system is the major brain activity affected by psychoactive drugs such as alcohol, nicotine, marijuana, cocaine, heroin and many other street drugs. The general rule is that many of these drugs attach to receptor proteins in the plasma membrane of neurons in brain. They may stimulate brain activity in the hypothalamus accentuating pleasures associated with eating or sex, and affect heart rate, respiration, sensory processing and muscle coordination. The body may develop tolerance to a drug by increasing liver enzymes needed to detoxify drug so that more drug may needed to feel any effect. Drug dependence or habituation may lead to addiction when one begins to crave the feelings associated with a drug and cannot begin to function "normally" without the drug. Drugs taken simultaneously may have certain dangerous interactions: synergistic effect - two drugs taken together have more of an effect than if taken separately. (Alcohol and barbituates both depress nervous system and when used together, can lethally depress respiratory centers in brain). antagonistic effect - one drug blocks the effect of another drug. potentiating effect - one drug enhances the effect of another drug (alcohol and antihistamines deepen the drowsiness caused by antihistamines in some people)

Divisions of Nervous System

The Nervous System is divided into two categories: Central Nervous System - consists of brain and spinal cord. Peripheral Nervous System - all nerves carrying signals to and from the central nervous system along with ganglia (swollen areas where cell bodies of sensory neurons reside)

Pelvic Girdle and Lower Extremities

The Pelvic girdle is larger and more basin-like in females than males for child bearing and birth. The Femur is the largest bone in the body and fits in a deep socket in the side of the pelvic girdle. The Tibia of the lower leg forms the "shin bone"; the fibula is more delicate and is not a weight-bearing bone of the leg but serves as a site for muscle attachment. The Patella is the kneecap and covers the vulnerable knee joint. Various ligaments in the knee joint can be torn or even separated due to injuries, especially while playing certain sports.

Peripheral Nervous System

The Peripheral Nervous System is composed of two general categories of nerves: Somatic Nerves - those nerves that innervate muscles and help move body parts; also included are those nerves that are sensory in function. Autonomic Nerves - those nerves innervating smooth muscles, cardiac muscle and glands. Autonomic nerves have two categories: Parasympathetic portion of autonomic system - nerves which function to preserve body resources, for example, slow down heart or respiration and stimulate digestive processes. Sympathetic portion of autonomic system - nerves which function in mobilizing body resources such as in "fight or flight" response. The heart rate and breathing rate increase and digestive functions stop

Actions of Skeletal Muscles

The body possesses over 600 muscles and their contraction produces movement. Gross movement of limbs and other parts of the body is the result of many muscles contracting through controlled and coordinated movements by groups of muscles as opposed to a muscle acting alone. Muscles many times attach to bones or soft tissue via tendons and usually attach at least to two points which most times spans a joint. The origin of a muscle is the attachment point that doesn't move and the insertion of a muscle is on the bone or soft tissue that moves is usually the most distal attachment. For the following discussion of classes of levers, be sure to review the definitions given in text for terms such as lever, fulcrum, effort and load. Classes of Levers and Examples the class of lever is dependent upon the position of the fulcrum in relation to the effort (force) and the load being moved. First class levers - in this class, the fulcrum is between the effort or force and the load. An example is the nodding movement at the atlantico-occipital joint. Second class lever - in this class, the load is placed between the fulcrum and the effort (force). An example is raising your heel from the ground. Third class lever - in this class, the effort (force) is between the fulcrum and the load. An example is the elbow joint.

States of Conciousness

The brain emits electrical signals which indicate levels of activity in brain neurons. These electrical outputs are called "Electroencephalograms"or EEG's. For example, a relaxed person emits an "alpha rhythm" so alpha waves are observed during meditation and early sleep. REM - (Rapid Eye Movement) accompanies dreaming and is a sign that someone is dreaming. EE Garousal - occurs during times of concentration when problem solving. Reticular Activating System (RAS) - located in the brain stem and controls changing levels of consciousness. For example, the RAS sleep center releases serotonin which cause drowsiness. Other neurotransmitters inhibit serotonin and keep us awake. Damage to the RAS can bring on coma, and anesthetics induce unconsciousness by suppressing the RAS. Memory is the ability to recall information about past experiences. Sensory information stimulates the cerebral cortex to bring on association, the packaging of information into larger pieces for recall. Short-term memory - is the ability to remember small amounts of data for periods lasting a few seconds to a few hours (a phone number or a street address). Long-term memory - is the ability to store memories for a lifetime and retrieved sometimes in response to certain cues. Alzheimer's Disease - usually occurs in late life but a few people in their 40's to 50's exhibit symptoms, i.e., forgetfulness, confusion, reduced ability to recover memories.

Length-Tension Relationship

The force with which a skeletal muscle can contract is related to the length of its sarcomeres (in experimental conditions, muscles can be stretched and the force of contraction measures). Minimal tension - when sarcomere filaments are completely understretched so few if any myosinheads are available for attachment to actin filaments. Understretched - sarcomere still understretched but a few more myosin and actin filaments are in contact with each other so some but not full contraction can take place. Maximal tension - happens when overlap zone of thin and thick filaments is ideal and happens when the overlap zone reaches from the H-band to the end of the thick filament. Overstretched - if sarcomere is overstretched, overlap between thick and thin filaments is reduced. Minimal tension - if no overlap between thick and thin filaments occurs because muscle is stretched beyond optimal range, no binding between actin and myosin filaments can occur.

BONES OF THE LOWER LIMB

The lower limb (appendicular skeleton) is connected to the axial skeleton by the pelvic girdle. The hip bones are known by several names but we'll refer to the collection of bones as the pelvis. The female pelvis is more round and wider than the male pelvis to permit passage of the head of the infant during childbirth. Hip Bone Each hip bone is made up of three bones - the ilium, ischium and pubis. It forms three articulations - sacroiliac joint with sacrum, pubic symphysis with the pubic cartilage and the hip joint with the head of the femur. Ilium: largest of hip bones, most superior edge known as the crest serves as attachment sites for abdominal muscles and can be palpated as the superior edge of the hip. The anterior superior iliac crest is a small projection at the most anterior point of the iliac crest and can also be palpated at the most anterior edge of the crest. This is the site of what is commonly known as a hip pointer, a painful injury following a blow to this region. Pubis smallest bone of hip, articulates with pubis bone on other side of pelvis. Ischium Tuberosity: large, roughened tuberosity on posteroinferior portion of ischium that provides attachment site for hamstring muscles. The ischial tuberosity is also palpable and is the site of the pelvis that we sit on. The Obturator formamen is a large foremen (hole) formed by the pubis and the ischium. The acetabulum is the cup-shaped depression formed by the ilium, ischium and pubis for articulation with the head of the femur. Femur Femur is the largest bone of the body and is located in the thigh. It articulates with the hip joint via the acetabulum, the knee joint with the tibial condyles and the knee via the posterior surface of the patella. The greater trochanter of the femur can be palpated on the side of the hip region. At the femur's most distal region, you can also palpate the lateral condyle located on the lateral surface of the knee joint and this articulates with the lateral tibial condyle, The medial condyle of the femur is located at the distal end and can be palpated in the medial portion of the knee joint where it articulated with the medial tibial condyle. Patella The patella is the largest sesamoid bone in the body and is embedded within the tendon of the quadriceps femoris muscle anterior to the knee joint. Tibia The tibia is the thicker bone of the leg and is the weight bearing leg bone. The anterior border can be palpated and is known as the "shin bone". The lateral and medial condyles can be palpated and articulate with the femur. The tibial tuberosity is located on the anterior aspect of the upper end of the tibial shaft and is the site for attachment of the patellar ligament. When you kneel on your knees, you are actually kneeling on your tibial tuberosity. The medial malleolus is located at the most distal end of the tibia and can be palpated as the bump on the medial portion of the ankle. Fibula The head of the fibula is located on the lateral surface of the knee and can be palpated. The lateral malleolus is located at the most distal region of the fibula in the lateral surface of the ankle. It articulates with the talus bone of the ankle. Bones of the foot Foot: composed of seven tarsal bones (all sesamoid), five metatarsals (miniature long bones) and two or three rows of phalanges (miniature long bones). Talus articulates with the tibia and fibula. The calcaneus is the largest tarsal bone and forms the heel on the foot.

Node to Node Hopping

The nerve axon on motor neurons is covered by a myelin sheath formed from SchwannCells that has nodes or indentations periodically so that impulse hops from node to node (see in online text, Nervous System, Nervous Tissue, click on Myelin sheath, also click on Myelination and read about Schwann cells). In multiple sclerosis, the myelin sheath is slowly destroyed causing muscle weakness, numbness and paralysis.

PANCREAS

The pancreas is located within the curve of the duodenum and stretches left horizontally as far as the spleen. The main functions of the pancreas are two-fold; (1) produce hormones glucagon and insulin which help control blood sugar levels by converting glucagon to glucose and vice versa. This constitutes its endocrine function. But, the pancreas also functions as an excocrine gland secreting pancreatic juice into the intestine for digestion of protein, starch and fats. The secretion of pancreatic juice into the intestine is through a main pancreatic duct which joins the common bile duct from the liver which opens into the intestine via the hepatopancreatic ampulla. About 99% of the pancreatic cells are exocrine and secrete many enzymes for digestion into the intestinal lumen. The remaining cells are organized into the Islets of Langerhans which secrete hormones into the bloodstream. The cells in the Islets of Langerhans and the hormones they secrete are listed below. Endocrine Glands Alpha (A) cells: secrete glucaogon and are located towards the periphery of the Islet of Langerhans. Beta (B) cells: secrete insulin and are located toward the center of the Islet of Langerhans. Delta (D) cells: secrete somatostatin and located on the periphery of the Islet of Langerhans. F cells: smaller number of cells that secrete pancreatic polypeptide. Exocrine Glands Pancreatic juice arises from pyramidal shaped cells located in clusters termed acini and contain digestive enzymes as well as bicarbonate to neutralize the acidic chyme (stomach acids and food) so that digestion can proceed in the more basic environment of the intestine. Hormones of the Pancreas Glucagon: produced by alpha cells of the Islets of Langerhans and target hepatocytes (liver cells). Principle action is to raise blood glucose by (1)speeding up conversion of liver glycogen to glucose, (2) speeding up conversion of lactic acid and amino acids to glucose and (3) stimulating hepatocytes to release glucose into blood stream. Insulin: polypeptide hormone composed of two amino acid chains which target most cells in body increase glucose uptake. Principle actions include (1) speed up glucose uptake by cells, (2) speed up conversion of glycogen to glucose by hepatocytes (glyconeogenesis), (3) increases amino acid uptake and protein synthesis, (4) speeds up fatty acid synthesis (lipogenesis), (5) slows down formation of glycogen from glucose and (6) slows down conversion of lactic acid and amino acid to glucose. Somatostatin: functions as an inhibitor of growth hormone and targets alpha cells, beta cells and cells of the GI tract. Principle action is of a paracrine nature in that ir inhibits insulin and glucagon release from alpha and beta cells. It also has endocrine action in that it slows absorption of nutrients from GI tract. Pancreatic polypeptide: is a polypeptide hormone that inhibits somatostatin secretion from Delta cells by paracrine action and inhibits secretion of digestive enzymes by pancreatic acini. Its endocrine action is to inhibit gallbladder contraction. Ghrelin: peptide hormone secreted by epsilon cells of pancreas and cells lining the fundus of the stomach and targets the brain to stimulate hunger. Control of the Secretion of Glucagon and Insulin Glucagon and insulin act antagonistically to regulate blood glucose levels. Hyperglycemia or hypoglycemia determines how much of these hormones are secreted. When blood glucose is high (hyperglycemic condition), more insulin is secreted and when blood glucose level is low (hypoglycemic condition), more glucagon is secreted. Hypoglycemia results from fasting and eating or feeding results in hyperglycemia.

Bones of the Pectoral Girdle and Arm

The pectoral girdle connects the arm via the head of the humerus to the scapula and the clavicle. Scapula: forms two articulations. Acromioclavicular joint between the acromion portion of the scapula with the acromial end of the clavicle. The glenoid fossa of the scapula articulates with the head of the humerus. Clavicle: slightly, S-shaped bone lies at base of neck and has two articulations. The acromioclavicular joint forms between the acromion of the scapula and the acromion portion of the clavicle. The sternoclavicular joint forms between the manubrium portion of the sternum and the clavicle. Humerus: articulates with the glenoid fossa of the scapula via the glenohumeral joint. Articulates with the trochlear notch of the ulna via the humeroulnar joint. Also articulates with the radial head via the humeroradial joint. Has the olecranon fossa which is a large fossa for articulation with the ulna. The medial epicondyle is a prominence that is an attachment for some muscles of the forearm but also is known as the site of the "funny bone" because the ulnar nerve runs nearby and when bumped at that site causes a tingling sensation in the forarm.

Skull

The skull is part of the axial skeleton and is made of 22 bones (most articulate via sutures). Cranial bones (neurocranium) surround and protect brain. Facial bones (viscerocranium) enclose, protect and support soft tissues of orbit, nasal and oral cavities. Eight bones are cranial bones which are the occipital bones, sphenoid bone, frontal bone, ethmoidbone, two parietal bones and two temporal bones. Fourteen bones are facial bones and they are two maxillae, two palatine bones, two zygomaticbones, two nasal bones, two lacrimal bones, the vomer, two inferior conchae and the mandible. The cranial cavity is the cavity in which the brain resides and has three large fossae - the anterior, middle and posterior cranial fossa.

Central Nervous System

The spinal cord is protected by vertebrae and ligments. Also surrounding the spinal cord are series of membranes termed meninges. The spinal cord consists of nerve tracts of myelinated and unmelinated fibers divided into white (myelinated) matter and gray (unmelinated) matter. White matter in spinalcord located on the outside and grey matter is on the inside in shape of a butterfly. Spinal cord functions consist of serving as a conduction pathway to and from the brain, and also as a site for reflex action (pulling hand away from a hot stove). Autonomic reflexes also exist such as emptying the urinary bladder when it becomes too full.

Spinal Cord

The spinal cord starts at the foramen magnum, descends in the vertebral column and consists of 31 spinal nerves (eight cervical, 12 thoracic, five lumbar, five sacral and one coccygeal. The spinal cord shows a cervical and a lumbar enlargement and ends at the conus medullaris at the level of L2. Cervical and Lumbar enlargement Cervical enlargement due to emergence of nerves of the brachial plexus and the lumbar enlargement due to emergence of nerves of the lumbar plexus. The conus medullaris is the termination of the spinal cord at the level of the second lumbar vertebrae. The cauda equine fills the vertebral canal below the second lumbar vertebra and consists of the nerve roots from the lumbosacral spine. There are three layers of fascia covering the spinal cord called meninges. The closest to the spinal cord is named the pia mater, then arachnoid mater and the outside layer is the duramater. The spinal meninges are continuous with the meninges surrounding the brain. Pia mater: rich with blood vessels supplying the spinal cord. Arachnoid mater: middle layer which forms a space around the pia mater for the presence of cerebral spinal fluid (CSF). A "spinal tap" is a procedure in which a hypodermic needles is inserted into the space between the arachnoid mater and pia mater so CSF may be removed for medical diagnosis. Dura mater: most superficial layer providing dense covering over spinal cord. Denticulate ligaments: thickenings of the pia mater that extend laterally and cover the posterior and anterior nerve roots on either side of the spinal cord. They anchor the spinal cord to the arachnoid mater and dura mater to keep the spinal cord suspended in the middle of the vertebral column, protecting it from sudden movements that could cause shock. Cross-Section of Spinal Cord In the spinal cord, the gray matter formed of neural cell bodies is located in the center and the white matter formed of myelinated nerve axons, vessels and neuroglia is located on the outside. This gray matter - white matter arrangement is just the opposite in the brain where the white matter is located on the outside and the gray matter on the inside. Nerve fibers similar origin and function travel together in the spinal cord in what is called spinal tracts. Spinal tracts are larger as you ascend the spinal cord because more nerves are traveling up and down the spinal cord as you go closer to the brain. Review in your online text in the spinal cord module the location and terms for describing the spinal cord such as for white matter, the anterior column located ventrally, lateral column and posterior column located dorsally. For the gray matter, note the location of the anterior or ventral horn, the lateral horn, the posterior or dorsal horn, the commissure and the central canal. Note that the gray matter is H-shaped in transverse section and is thickest in the cervical and lumbar sections because of the large number of neurons needed to supply the upper and lower limbs. The central canal runs the entire length of the spinal cord and extends into the medulla oblongata where it opens into the fourth ventricle and is lined by columnar epithelium and contains cerebrospinal fluid (CSF).

MUSCLES OF THE THIGH

The thigh has four strong muscles located on the anterior surface called the quadriceps which function to extend the knee and on the back of the thigh, there is a group of muscles called the hamstrings which function to flex the knee. Anterior Compartment: Vastus lateralis - most lateral of the quadriceps with origin on the greater trochanter of the femur, insertion on the tibial tuberosity via the patella tendon and an action to extend the knee. Vastus medialis - most medial of the quadriceps with origin on linea aspera of femur, insertion on tibial tuberosity via patellar tendon and action is to extend the knee. Vastus intermedius - deepest of the quadriceps with origin on shaft of femur, insertion on tibial tuberosity via patellar tendon and action to extend the knee. Rectus femoris - most anterior of quadriceps with origin on anterior superior iliac spine and acetabulum of the hip bone, insertion on the tibial tuberosity via patellar tendon and action to extend the knee. Sartorius - longest muscle in the body, travels obliquely across front of thigh with origin on anterior superior iliac spine of hip, insertion on tibia and action to flex the hip and knee and rotate the femur. Posterior Compartment primary action of muscles in this compartment is to flex the knee joint and extend the hip. Biceps femoris - most lateral hamstring and arises from two heads with origin of long head on ischial tuberosity of hip and linea aspera of femur, insertion on head of fibula and action to flex the knee and extends the hip. Semitendinosus - the most middle hamstring and becomes a long tendon with origin on the ischialtuberosity of hip, inserts on the tibia with action that flexes the knee and extends the hip. Semimembranosus - most medial hamstring with origin on ischial tuberosity of hip, insetion on tibia and action to flex the knee and extend the hip. Medial Compartment Primary action of muscles in medial compartment is to adduct the hip joint but can help with lateral rotation and flexion of the hip. Adductor magnus - large flat muscle of the medial thigh with origin on pubis and ishium of hip, insertion on linea aspera on femur and has an action to adduct the hip. Adductor longus - flat muscle of medial thigh with origin on publis of hip, insertion on linea asperaof femur and action to adduct and laterally rotate the hip. Adductor brevis - short muscle of medial thigh with origin on pubis of hip, insertion on linea asperaof femur and action to adduct and laterally rotate hip. Gracilis - long thin muscle on medial side of the thigh with origin on pubis of hip bone, insertion on tibia and action to adduct the hip and flexes the knee.

THYROID AND PARATHYROID GLANDS

The thyroid and parathyroid glands are located anterior to the trachea with four parathyroid glands embedded in the posterior surface of the thyroid. The thyroid and parathyroid glands are, however, two separate endocrine glands. The thyroid regulates metabolism and also affects growth, development and normal functioning of several body systems. The parathyroid glands control the level of calcium circulating in the blood and within bones. The thyroid gland synthesizes and stores thyroid hormones that affect heart rate, blood pressure, body temperature, energy production and overall body metabolism thereby affecting all body organs. It has a right and left lobe with a central strip connecting the two lobes called the isthmus. It is located in front of the trachea at the level of C7 - T1. Microanatomy of the Thyroid Gland Histological views of the thyroid show it to be full of spherical follicles surrounded by a capillary network. The walls of the thyroid follicles are formed of epithelial cells which produce thyroid hormone precursor thyroglobulin. Thyroglobulin forms T3 and T4 as active thyroid hormones. Between the follicles, there are present some secretory parafollicular cells which produce calcitonin. Calcitonin works in opposition to the hormones produced by the parathyroid glands in that it lowers level of calcium in the blood. Hormones of the Thyroid Gland T4 or tetraiodothyronine and T3 triiodothyronine are two different thyroid hormones produced by the thyroid follicular cells. They both are constructed from two linked tyrosine amino acids but differ in their iodine content. T4 increases oxygen consumption and body metabolism, increases heart rate and blood pressure and many other overall bodily functions (see online text for full list of functions) T3 appears more potent than T4 but its action is not as immediate. Calcitonin is a polypeptide produced by parafollicular cells sometimes called C cells. Calcitonin opposes action of parathyroid hormones and lowers blood level of calcium. Review in online text the "Synthesis, Secretion and Transport of T3 and T4" and also the "Actions of T3 and T4". If the basal metabolic rate (BMR) drops below a certain set point or the levels of T3 and T4 in blood becomes low, the hypothalamus secretes thyrotropin-releasing hormone into the hypophyseal portal system which takes it to the anterior pituitary which then secretes thyroid stimulating hormone or TSH. TSH then travels to thyroid where it stimulates the thyroid follicular cells to secrete more thyroglobulin and promotes release of T# and T4 into the blood. As the BMR gets back to normal the elevated levels of T3 triggers a negative feedback inhibition of TRH and TSH secretion. Cold and also pregnancy increases secretion of T3 and T4 which increases metabolic rate so that more ATP is produced. Parathyroid Glands Parathyroid glands are small, rice grain size, and form two superior and two inferior glands located on the posterior surface of the thyroid. Primary cells of parathyroid are the chieh cells which are numerous and secrete parathyroid hormone. There are also some larger and paler cells called oxyphil cells for which a function is not known. Review the "Actions of Parathyroid Hormone" in your online text. Calcium Homeostasis Review in your online text the components of the feedback loop for Hypercalcemia and Hypocalcemia. Know what the following terms and what they mean for each condition - stimulus, receptor, control center, effector and response.

RIBS

The twelve pairs of ribs all articulate with thoracic vertebra but only ribs 1 - 7 attach anteriorly to the sternum and these ribs are called true ribs. Ribs 8 - 10 attach by cartilage to the 7th costal cartilage and are known as false ribs. Ribs 11 and 12 do not attach to the sternum and are called floating ribs.

Appendicular Skeleton

The word "append" means to hang, thus the appendicular skeleton comprises those skeletal components which hang or dangle from our torso, i.e., arms, hands, legs and feet plus their supporting structures, the pectoral and pelvic girdles. Pectoral Girdle and Upper Limbs The Pectoral Girdle is composed of the clavicle and scapula. The Humerus of the upper arm articulates with both bones. Radius (thumb side) and ulna (little finger side) of forearm articulate with the humerus to form the elbow joint. We have a great range of movement at the pectoral girdle site of articulation of the upper arm because the pectoral girdle is relatively loosely attached to the body frame (axial skeleton). It is vulnerable, however, to damage from strong blows or from falls. The Proximal end of the ulna forms the elbow. At the wrist joint, tendons are enclosed in sheaths which can become inflamed due to repetitive movements, such as typing, to produce carpal tunnel syndrome.

MUSCLES OF THE HAND

Thenar group of muscles control the movement of the thumb in all directions. Hypothenar group of muscles control the movement of the little finger. Compartments of the upper limb - muscles of the upper limb are divided into compartments formed by layers of fascia which binds the muscles and forms septa between muscle groups.

MUSCLES OF THE BODY

There are over 600 muscles in the human body. For our study, I have chosen about 60 or so muscles for our study and I have listed them below according to their body locations. For the muscles below, you are expected to know their location, insertion, origin and action. Be sure to utilize the online text to see these muscles in their body location and to note what they move when they contract and to what bones and other body parts they are attached. Also keep in mind that movement of the body parts or regions is the result of more than one muscle contracting

Joints

There are three major types of Joints based on morphology (structure): Synovial joint are joints which have capsules that secrete slippery synovial fluid into joint to make movement more easy.Examples of synovial joints are the "ball and socket" joints - femur to pelvic girdle and hinge-like joints such as the knee or elbow joint Cartilaginous joints - cartilage fills space between bones, not much movement such as with breastbone (sternum) and some ribs Fibrous joints - fibrous tissue connects bones of fetal skull, permitting brain to grow after birth. This gives rise to "soft spots" on baby's head. These joints harden into sutures later when brain growth ceases. Joints may also be classified based on their function: Synarthroses - joints that do not provide any movementExample of synarthroses is the sagittal suture between two parietal bones. Amphiarthroses - joints that only provide a small degree of movementExample of amphiarthroses is the intervertebral joints between vertebral bodies. Diarthroses - joints that allow free movements such as the knee or shoulder joiints. In your online Anatomy & Physiology text, read and study information on anatomy of Synovial Joints under the topics - Articular cartilage, Synovial cavity, Articular capsule, Synovial fluid, Accessory ligaments, Articular fat pad and Bursae and tendon sheaths. Movements Possible about a Synovial Joint Abduction - adduction: Abduction is moving an arm or leg away from the body, adduction is moving arm or leg toward the body. With fingers - spreading fingers is abduction, bringing fingers together is adduction. Flexion - extension: Flexion is bringing two bones closer together, extension is widening the angle between two bones. Hyperextension is widening the angle between two bones more than the normal amount. Elevation - Depression: Elevation moves bone vertically upward such as lifting the scapula. Depression moves bone vertically downward such as lowering the scaplula downlwards. Protraction - Retraction: Moves a joint horizonatally forward such as moving the scauplaforward. Retraction moves a joint horizontally backwards such as moving the scapula backwards. Lateral excursion - Medial excursion: Lateral excursion moves mandible laterally. Medial excursion moves mandible medially. Circumduction - moving the arm in as wide a circle as possible. Combination of flexion, extension, abduction and adduction. Rotation: Moves a bone around its axis such as moving the head left and right as in saying no. Lateral rotation - Medial rotation: Turns a bone laterally on its longitudinal axis such as lateral rotation of the forearm. Medial rotation turns a bone medially on its longitudinal axis such as in medial rotation of the forearm. Supination - Pronation: Supination rotates forearm and hand and the foot and ankle upwards as in rotating the forearm so that the palms face upwards or in the anterior direction. Pronation rotates forearm and hand or the foot and ankle downwards such as rotating the forearm so the palms face downward or backward. Opposition - Reposition: Opposition moves the thumb towards the fingertips and reposition moves the thumb away from the fingertips. Dorsiflexion - Plantarflexion: Dorsoflexion flexes the ankle joint (moves foot to close angle between foot and leg). Plantarflexion extends ankle joint (moves foot away from leg). Inversion - Eversion: Inversion lifts medial side of the foot (twisting foot so that sole faces inward toward center line of the body. Eversion lifts lateral side of foot so that sole faces outward away from the center line of the body.

THORACIC CAGE

Thoracic cage formed from twelve thoracic vertebra, twelve ribs and the three bones of the sternum. Sternum: flat bone in middle of chest composed of manubrium, body and xiphoid process. The manubrium is the most superior portion of the sternum and articulates with the first and second ribs via their costal cartilages. The Body portion is the largest bone of the sternum and articulates with the costal cartilages of ribs 3 - 7. The Xiphoid process is the most inferior portion of the sternum.

MUSCLES OF THE HIP

Two muscles are strong flexors of the hip and together are termed the iliopsoas which originate in the trunk and pelvis and distally, their tendons merge to form a tendon that inserts on the lesser trochanter of the femur. iliacus - large fan-shaped muscle that occupies the inside the ilium and the origin is the iliac fossaof the hip, insert on the lesser trochanter of the femur and has an action of flexing and abducting the hip and flexes the trunk. Psoas major - long thick muscle that lies on the posterior abdominal wall and forms a conjoined tendon with the iliacus. The origin is on the T1 - L5 vertebra, insertion is on the lesser trochanter of the femur and action is flexing and abducting the hip and flexes the trunk.

SOME EXTENSORS OF THE WRIST AND HAND

We will look at only a few of the forearm extensors but all the extensor tendons travel beneath the extensor retinaculum which holds the extensor tendons in place when muscle contraction occurs. The primary action is to extend the elbow joint but do participate in supination of the forearm and abdunction/adduction of the hand. Superficial Extensors: Anconeus - small triangular muscle on lateral side of elbow with origin on the lateral epicondyle of humerus, insertion on olecranon of ulna and action of extending the elbow. Extensor digitorum - thin muscle of anterior forearm that divides into four thin tendons digitally which have an origin on the common extensot tendon and insertion on fingers 2 - 5 and an action of extending the wrist and finger 2 - 5. Deep Flexors: Brachioradialis - thin muscle located on the front of the forearm with origin on humerus, insertion on styloid process of radius and flexes the elbow. Pronator quadratus - small square muscle that lies on the anterior distal forearm with origin on ulna, insertion on radius and action to pronate the forearm. Flexor digitorum profundus - thin muscle of the posterior forearm that divides into four thin tendons distally with origin on ulna, insertion on phalanges 2 - 5 with an action to flex the wrist and fingers 2 - 5. Flexor pollicis longus - thin muscle of the posterior forearm and thumb with origin on the ulna, insertion on the 1st distal phalanx and action to flex the thumb. Superficial Flexors: Pronator teres - thin muscle that crosse the front of the elbow with origin on humerus and coronoidprocess of ulna, insertion on radius and action to flex elbow and pronate forearm Flexor digitorum superficialis - thin muscle of posterior forearm into four thin tendons distally with origin on common flexor tendon, insertion on middle phalanges 2 - 5 and action of flexes fingers 2 - 5.

Control of Contraction

What happens when a motor neuron stimulates a muscle to contract? (See Excitation-Contraction Coupling topic in Physiology section of online A & P text. An electrical signal termed an action potential or impulse speeds down the axon to the muscle fibers. At the neuromuscular junction (myoneural junction), the nerve endings release acetylcholine(Ach) into the space between the nerve ending and muscle fiber known as the synapse. The Ach begins the electrical impulse that spreads over the muscle fiber and causes the sarcoplasmic reticulum (smooth ER) in the muscle fiber to release Calcium ions. The Calcium ions bind to troponin molecules on the actin filament, it changes the conformation (shape) of actin filaments allowing myosin cross bridges to bind to actin. When electrical stimulation stops, energy from ATP is used to pump Calcium back into sarcoplasmic reticulum allowing troponin and tropomyosin to rebind with myosin stopping contraction and allowing the actin filaments to slide back to the relaxed position in the sarcomere.

Twitch Contractions

What is a twitch contraction? A twitch contraction is a fast, brief contraction of a muscle following a single stimulus and the recording of that twitch is called a myogram. Latent period - time that passes between stimulation of the muscle and contraction of that muscle (we're talking now about a muscle, not a muscle fiber.) During the latent period, the action potential caused by the stimulus is spreading over the myofiber sarcolemma causing Calcium to be released by the sarcoplasmic reticulum. This period lasts around 2 msec. Contraction period - during this period, crossbridge formation occurs due to buildup of Calcium ion concentration and sarcomere length is decreasing (undergoing contraction), muscle tension rises and this period lasts about 15 msec. Relaxation period - once peak tension has occurred and stimulation stops, calcium ions are taken back up into sarcoplasmic reticulum with coverage of myosin head binding sites. This causes detachment of crossbridges and reduction in muscle tension. This period lasts about 25 msec. Skeletal muscle fibers contract either slowly and are called "slow twitch fibers" or fast and are called "fast twitch fibers". Their speed is dependent upon how fast ATPase in the myosin heads can hydrolyze ATP. Slow twitch fibersThese fibers regenerate ATP mainly via aerobic respiration which is slow but have many large mitochondria and high levels of myoglobin which gives these muscles a red color. The high levels of mitochondrial enzymes provides them with a sustained mechanism by which they use energy and makes them fatigue resistant. Slow twitch fibers are found in large muscles such as the gluteals. Fast twitch fibers - generate ATP at a faster pace than slow twitch fibers. Their sarcoplasmicreticulum also releases and takes up calcium ions faster. They also hydrolyze ATP faster and rely upon anaerobic respiration to generate short term energy transfer for contraction. Fast twitch fibers develop tension 2-3 times the rate of slow twitch fibers but do tire more quickly because of that. An example of fast twitch fibers can be found in the intrinsic muscles of the eye. Frequency of Stimulation (see Contraction information in Skeletal Muscle unit of online A & P text) - When a muscle (such as in an isolated frog gastrocnemius muscle) is stimulated at different frequencies, the following types of myograms can be seen. Summation - wave summation is seen when the stimuli are delivered to a muscle fiber in quick succession which causes an increase in force of contraction. Incomplete tetanus - incomplete tetanus occurs when muscle stimulation occurs soon after the absolute refractory period (time when a following sequence causes no effect) but before the muscle can completely relax. The tension in the muscle gradually increases to its maximum. Complete tetanus - complete or fused tetanus occurs when sustained contraction happens with no chance for relaxation. Complete tetanus happens when a fiber is stimulated over 90 times a second. Complete tetanus is primarily a laboratory phenomenon and rarely happens in vivo.

Muscles that act to move a limb away from the midline of the body commonly have which one of the following terms as part of their name?

abductor

what is the origin of the external intercostals?

inferior borders of ribs 1 - 11

Carbohydrates

o Carbohydrates: - Carbohydrates are a group of organic compounds formed by the elements carbon, hydrogen, and oxygen. The term carbohydrate refers to the ratio of carbon to hydrogen and oxygen atoms in the molecule: for every atom of carbon there are two hydrogen atoms and one oxygen atom, the same as in water. Each carbon is, therefore, 'hydrated'. - Carbohydrates account for approximately 1-3% of our body mass. They are commonly consumed in our diet in a variety of food stuffs as simple sugarsand complex carbohydrates. Within the body, carbohydrates play a central role as the main source of energy. Some also form the structural components of DNA and RNA. There are three main classes of carbohydrate: monosaccharides, disaccharides, and polysaccharides. - Monosaccharides are simple sugars. They are the smallest and simplest of the carbohydrates and form the basic units, or monomers, of the more complex carbohydrates. Common monosaccharides include glucose and fructose, which occur naturally in fruit and plant juices. Monosaccharides are known as fast release carbohydrates, as they are easily absorbed into the bloodstream, releasing energy quickly. Other monosaccharides include the structural carbohydrates deoxyribose and ribose, that form the backbone of DNA and RNA molecules. - Disaccharides are made up of two monosaccharides joined together and include sucrose, which is commonly known as table sugar, lactose, found in dairy products such as milk, and maltose, found in grains such as barley. Disaccharides are too large to pass through cell membranes. As a result, they must first be broken down into monosaccharides before they can be used as an energy source. - Polysaccharides are complex carbohydrates that contain long chains of monosaccharides. Like disaccharides, they cannot pass through cell membranes, so are broken down or stored in the body for future use. Common polysaccharides include starch, cellulose, and glycogen. They are known as slow release carbohydrates, as they take time to break down, thereby maintaining a steady blood glucose level. Starch is commonly found in potatoes and grain products such as pasta, rice, and bread. - Cellulose is found in the cell walls of plants such as fruits, vegetables, nuts, and grains. Unlike starch, our bodies lack the enzyme that breaks down cellulose, making it largely indigestible. It therefore forms a large proportion of dietary fiber, important in the healthy functioning of the intestinal tract. Glycogen is found in the diet in the form of animal meat and liver. It is also made and stored in the body in liver and muscle cells. Any ingested starch and soluble cellulose not required for energy is metabolized into monosaccharides, which are then synthesized into long, branching chains of glucose monomers in the form of glycogen in the liver and muscles. o Monosaccharides: - Monosaccharides are the simplest type of sugar ('mono' = one, 'saccharide' = sugar). They are the basic units (monomers) used to build larger, more complex carbohydrates. - Structure: - Monosaccharides consist of a carbon backbone, either as a ring or as a chain, from which other chemical groups project. They have the general structural formula of Cx(H2O)ywhere x is a number from three to seven.Monosaccharides are named according to the number of carbon atoms they possess. For example, glyceraldehyde is a triose because it has three carbons, and glucose is a hexose because it has six carbons. - Source: - Common monosaccharides include pentose sugars (such as ribose and deoxyribose), and hexose sugars (such as glucose, fructose, and galactose). Glucose, fructose, and galactose are commonly obtained from fruit and plant juices. - Function: - Monosaccharides function mainly as a short term energy source. - Structural compoenent of DNA and RNA - Deoxyribose is a pentose that is used as a building block for the backbone of DNA molecules. Deoxyribose molecules provide structural support and form a framework between the bases of DNA, enabling the formation of the structurally stable double helix.Ribose performs a similar structural role in RNA, although RNA does not form a double helix. o Disaccharides: - Disaccharides are also simple sugars. They are often sweet to taste, and are soluble in water. Many foods contain disaccharides; however, they must first be broken down into their simpler, smaller molecules before they can provide useful energy. Artificial sweeteners are often used in place of disaccharides such as sucrose. They are sweeter, contain fewer calories, and limit tooth decay. - Structure: - Disaccharides consist of two monomers joined together via glycosidic bonds. These two monosaccharides unite via a dehydration reaction to create a disaccharide, where one water molecule is removed per glycosidic bond created. - Source: - Sucrose is formed from glucose and fructose. It is commonly referred to as table sugar. Maltose is formed from two glucose molecules. It is commonly found in grains such as barley. Lactose is formed from glucose and galactose. It is commonly found in dairy products. - Function à energy source - Disaccharides function mainly as a short-term energy source. The metabolism of disaccharides into monosaccharides feeds into metabolic processes, such as glycolysis and anaerobic respiration, where the breakdown of carbohydrates contributes to the production of ATP. o Polysaccharides: - Polysaccharides are known as complex carbohydrates. They are often insoluble in water, and unlike monosaccharides and disaccharides, do not taste sweet. - Structure: - Polysaccharides are very large molecules of sometimes hundreds of monosaccharides linked together by glycosidic bonds through dehydration synthesis reactions - Source: - Glycogen is a large, branched structure that is synthesized in the body in times of excess blood glucose levels. It is used as a storage molecule for sugar, in the skeletal muscle cells and in the liver cells, in order to act as a reservoir of energy when glucose levels in the body drop. Starch, also known as amylose, is a term given to the polysaccharides made in plants from glucose. It is taken into the body through the consumption of foods rich in starch, e.g., rice and pasta.Cellulose, commonly referred to as fiber, is a largely indigestible polysaccharide that is a major component of plant cell walls. - Function --> energy storage: - Polysaccharides are large insoluble molecules, which make them useful storage products. Ingested starch and soluble cellulose that is not required for immediate energy is metabolized into monosaccharides, which are then synthesized into long, branching chains of glucose monomers in the form of glycogen in the liver and muscles. - Function --> regulate of blood glucose levels - When blood glucose levels fall, glycogen stores are broken down during a process known as glycogenolysis, and released into the blood to bring blood glucose levels back to normal. When blood sugar levels rise, glucose is taken up from the blood by cells in the liver and skeletal muscle and used to form glycogen, in a process called glycogenesis.

Cell division

o Cell division: § Cell division is the process by which cells reproduce. There are two types of cell division: somatic cell division and reproductive cell division. Somatic cell division is simple replication, in which a single cell divides into two cells; the chromosomes in the replicated 'daughter' cells are identical to the original 'parent' cell. It occurs in every cell in the body apart from the sex cells, or gametes.Reproductive cell division occurs in the gametes, and is a process of reductional cell division, that is, the offspring cells have half the number of chromosomes as the original cell. o Somatic cell division § Somatic cells are diploid, meaning that they contain two sets of chromosomes, or 23 pairs of chromosomes, giving a total of 46. Somatic cell division is the process by which a diploid somatic cell replicates itself to form two identical diploid somatic cells i.e., the diploid somatic cell's products are identical to that of the starting somatic cell. Somatic cell division is important in the production of new cells during tissue growth, and the constant replacement of dead or damaged cells throughout life. The divisional process is known as the cell cycle. o Cell cycle § The cell cycle is the sequence of events that occurs leading up to and during somatic cell division. There are two main parts of the cell cycle: interphase (during which a cell prepares to divide) and the mitotic phase (during which division occurs).Interphase itself consists of three main subphases: G1, S, and G2. § During G1, the cell becomes highly active, preparing for division by duplicating many of its organelles and synthesizing proteins.In the S phase, the cell replicates its DNA, so there are two complete copies available.The final part of interphase is G2, during which the cell continues to increase in size and produce further proteins necessary for division.After G2, the cell enters the second part of the cell cycle: the mitotic phase. The mitotic phase consists of two processes, mitosis (the division of the nucleus) and cytokinesis (the division of the cytoplasm). § Mitosis has four stages: prophase, metaphase, anaphase, and telophase.By the end of mitosis, the DNA that was duplicated in the S phase of interphase has been separated into two identical sets, each within its own nucleus.Cytokinesis is the division of the cytoplasm to form two separate cells. Occurring at the same time as the final phases of mitosis, a contractile ring develops and deepens to divide the cell in two. Therefore, at the end of the mitotic stage, one cell has divided to form two daughter cells, each with a complete set of DNA.After dividing, the daughter cell re-enter G1. Each cell may then prepare to divide again, or pause, in which case, it is referred to as being in G0, or the quiescent phase.A cell may remain in G0 indefinitely, or later return to complete G1. o Interphase § Interphase is the longest phase in the cell cycle, accounting for DNA replication, production of additional organelles, and cytosol and cell growth. During this time, the cell contains a tangled mass of chromatin within a fully formed nuclear envelope. Interphase is subdivided into four phases: G0,G1, S phase, and G2. S denotes synthesis and refers to DNA replication, and G denotes gaps when no DNA replication is occurring. o G0 Phase § Some cells enter a quiescent, non-dividingstate after mitosis, where the cell cycle is suspended, and they do not enter G1. This is known as the G0 phase and is common in fully differentiated cells, such as skeletal muscle cells and neurons. o G1 Phase § The G1 phase, also known as gap 1 (or growth phase 1), can range between 8 and 10 hours. The cell is highly metabolically active during G1, with the following cellular activities taking place: - Replication of organelles. - Synthesis of cytosolic components (e.g., enzymes required during the S phase). - Beginning of centrosome replication. o S Phase § The S phase, also known as the synthesis phase, lasts about 8 hours, during which DNA replication occurs, ensuring that the two daughter cells produced acquire equal and identical sets of chromosomes. For more information, see 'Cell Biology: Protein Synthesis and DNA Replication'. o G2 Phase § The G2 phase, also known as gap 2, lasts about4-6 hours, during which the following occurs: - Replication of organelles completed. - Synthesis of cytosolic components completed. - Centrosome replication completed. - Protein synthesis. - Energy production for cell division o Mitosis § Mitosis is the term used to describe nuclear division. It is the exact duplication of 46 chromosomes into two separate nuclei. This process occurs during the mitotic phase of cell division along with cytokinesis: the division of the cytoplasm. Mitosis occurs in four phases known as prophase, metaphase, anaphase, and telophase. o Prophase § Early prophase: · During early prophase, chromatin fibers condense and shorten to form chromosomes. The nuclear membrane and nucleolus disappear, and centrioles begin to move towards the poles. As this genetic material was duplicated earlier in the S phase of the cell cycle, each chromosome is formed by a pair of identical strands known as chromatids. The chromatids are held together by a central body known as a centromere, which is surrounded by a protein complex known as the kinetochore. § Late prophase: - During late prophase, the mitotic spindle, formed of microtubules, extends frompericentriolar material at either pole to the center of the cell.The spindle microtubules attach to the kinetochore of each chromosome as the nuclear envelope breaks up and the nucleolus diminishes. o Metaphase § During metaphase, chromosomes are led by the mitotic spindle to line up along the metaphase plate, which lies across the midline of the cell. o Anaphase § Early anaphase: - During early anaphase, the centromere and kinetochore at the center of each chromosome splits, allowing them to separate into individual sister chromatids. The sister chromatids become distinct sister chromosomes and are pulled to opposite poles of the cell by the mitotic spindle microtubules still attached to the kinetochore § Late anaphase: - During late anaphase, the sister chromosomes are pulled further apart as the microtubules shorten. Additional microtubules, extending from pole to pole and not attached to a kinetochore, start to lengthen, elongating the cell in preparation for cytokinesis, and the cytoplasm of the cell begins to divide. o Telophase § In the final phase of mitosis, telophase, the nuclear envelope reforms, the nucleolus reappears, and the chromosomes uncoil back into chromatin.Microtubules, extending from pole to pole and not attached to a kinetochore, lengthen, elongating the cell in preparation for cytokinesis. Once the cell has split in two, the microtubules of the mitotic spindle break up. Towards the end of mitosis, cytoplasmic division, known as cytokinesis, occurs. Together, mitosis and cytokinesis result in two daughter cells, each containing a complete set of the chromosomes. o Cytokinesis § Cytokinesis is the term used to describe cytoplasmic division. Cytokinesis occurs from midway through anaphase, through to the end of telophase when the cytoplasm has divided fully: forming two separate cells. o Contractile ring § Towards the end of late anaphase, a contractile ring develops along the line previously occupied by the metaphase plate. o Cleavage furrow § The contractile ring pinches the cell cytoplasm along the midline, forming a cleavage furrow. As the cleavage furrow deepens, the cell splits into two identical diploid cells, each with its own nucleus and surrounding cytoplasm o Control of cell division § Within the cell cycle, a cell may have three possible fates: it can grow and proliferate, it may remain alive in a resting state without dividing, or it can die.The signals determining how and why a cell divides are not yet fully understood; however, it is known that an increase in cell size triggers cell division. The cell cycle is also tightly regulated by various chemical signals that stimulate the interaction of specific proteins, triggering the various stages of the cell cycle. The most important of these are cyclin, and cyclin-dependent kinases. o Cyclin § Cyclins are a family of regulatory proteins that vary in concentration throughout the cell cycle. In general, the levels of cyclins rise throughout the cell cycle, but decrease rapidly towards the end of mitosis. § Function: - Cyclin binds to the active site on the enzyme CDK. The formation of this complex causes and increase in CDK activity, which drives the cell cycle. o Cyclin-dependent kinase § Cyclin-dependent kinases (CDKs) are a family of enzymes maintained at a constant level of concentration throughout the cell cycle. § Function: - When bound to a cyclin protein, the active site of the CDK enzyme becomes only partially active. For complete activation to occur, CDK catalyzes the transfer of a phosphate group from ATP, to a specific protein at different stages of the cell cycle. The activation of these proteins initiates a cascade of events, allowing the cell to progress through to the next phase of the cell cycle. o Cell cycle checkpoints § Throughout the cell cycle, there are a number of checkpoints, which help to ensure that cell division is proceeding correctly. These checkpoints look for inaccuracies, or errors that occur within a cell during cell division, before that cell continues to the next phase.Some of the important checkpoints include: § G1 Phase checkpoint - Also known as the restriction point, the G1 checkpoint is located midway through the G1 phase of the cell cycle. If cell division is halted at this point, a cell will enter the G0 phase, until it is signaled to re-enter the cell cycle and continue dividing. § G2 Phase checkpoint - The G2 checkpoint is located towards the end of the G2 phase. This checkpoint requires a threshold level of a protein called M-phase promoting factor (MPF). When this threshold level is reached, a cell is allowed to progress to the mitotic phase. MPF is inactivated towards the end of the M phase. § M phase checkpoint - The M phase checkpoint is situated during the metaphase period of mitosis. If the chromosomes are successfully aligned along the metaphase plate, cell division continues onto anaphase. After the cell successfully divides, its daughter cells re-enter the G1 phase. § In addition to the regulatory controls that exist during the cell cycle, the body is able to eliminate poorly functioning or redundant cells by two different mechanisms. o Apoptosis § Apoptosis is the process of normal or programmed cell death. It is triggered by signals such as a cell failing to pass a checkpoint, or external signals that stimulate the production of damaging enzymes that degrade and digest the cell; phagocytes then ingest and remove the remaining cellular debris. o Necrosis § Necrosis is the term used to describe pathological cell death, as a result of external factors, such as infection, toxins or trauma. During necrosis, cells swell and burst, emptying their cytoplasmic contents into the interstitial fluid surrounding them, which usually triggers an inflammatory response by the immune system. o Reproductive cell division § Reproductive cell division only occurs in the gonads (ovaries and testes). It is the process by which gametes are formed from a germ cell. During reproductive cell division, diploid germ cells, containing two sets of chromosome pairs, must undergo mitosis, meiosis, and cellular differentiation before developing into mature gametes (ovum or sperm). The resulting gametes, or sex cells are haploid, meaning they contain only one set of 23 chromosomes, half the amount of somatic cells. The production of gametes is essential for the joining of two genomes during sexual reproduction. Before reproductive cell division, a germ cell must follow the equivalent preparatory steps as a somatic cell, proceeding through the G1 and S phases of the cell cycle. However, germ cells do not pass through the G2 phase; instead they stop at the end of the S phase.Unlike mitosis, which occurs in one single round, reproductive cell division occurs in two successive rounds: meiosis I and meiosis II. § Meiosis I - Meiosis I is sometimes referred to as reductional division, as the number of chromosomes in each cell is reduced from the diploid number of 46, to the haploid number of 23. § Prophase 1 - stage 1 - During early prophase I, chromatin fibers condense and shorten to form individual chromosomes. § Prophase 1 - Stage II - During late prophase I, the mitotic spindle, composed of microtubules, extends from pericentriolar material at each pole to the center of the cell. The spindle microtubules attach to the kinetochore of each chromosome as the nuclear envelope breaks up and the nucleolus diminishes. § Prophase 1 - Stage III - In contrast to mitosis, the chromosomes are arranged in homologous pairs. Each pair of chromosomes contain a maternal and paternal copy. These copies contain similar genes, arranged in the same location as one another. § Metaphase I - During metaphase I, homologous pairs of chromosomes line up along the metaphase plate.Sections of DNA may be exchanged between the two chromosomes of each homologous pair through a process known as crossing-over, which generates genetic variation. § Anaphase I - During anaphase I, the microtubules attached to each kinetochore shorten and one complete chromosome from each homologous pair is pulled towards each pole of the cell. Microtubules, extending from pole to pole and not attached to a kinetochore, start to lengthen, elongating the cell in preparation for cytokinesisand the cytoplasm of the cell begins to divide.In contrast to mitosis, during meiosis I, the chromatids of each chromosome do not separate. § Telophase I - During telophase I, the nuclear envelope reforms.Cytokinesis is completed, and the microtubules of the mitotic spindle break up. The two haploid daughter cells each contain half the number of chromosomes as the original germ cell. In females, one of the daughter cells will form a polar body and degenerate. o Meiosis II § Daughter cells formed during meiosis I, which have not degenerated, now enter the second stage of meiosis (meiosis II). The events of meiosis II are similar to mitosis. § Prophase II: - The nuclear membrane breaks up and the mitotic spindle, formed of microtubules, extends from pericentriolar material at either pole to the center of the cell. The spindle microtubules attach to the kinetochore of each chromosome as the nuclear envelope breaks up and the nucleolus diminishes. § Metaphase II - Chromosomes, led by the mitotic spindle, line up along the metaphase plate along the midline of the cell. § Anaphase II - The centromere and kinetochore at the center of each chromosome split, allowing them to separate into individual sister chromatids. The sister chromatids become distinct chromosomes and are pulled to opposite poles of the cell by the mitotic spindle microtubules still attached to the kinetochore. Microtubules, extending from pole to pole and not attached to a kinetochore, lengthen, elongating the cell in preparation for cytokinesis, and the cytoplasm of the cell begins to divide. § Telophase II - The nuclear envelope reforms, the nucleolus reappears, and the chromosomes uncoil back into chromatin.Once the cell has split in two, the microtubules of the mitotic spindle break up.In females, one of the resultant daughter cells will degenerate into a polar body. At the end of meiosis, one diploid germ cell has been divided to form four gametes in males, whereas in females, only one functional gamete has been produced.