Biology owo

Erythropoietin

A hormone produced and released by the kidney that stimulates the production of red blood cells by the bone marrow.

Female sexual development

FSH causes estrogen secretion which develops/maintains female repro system and female secondary sexual characteristics Estrogen also leads to thickening of lining in uterus (endometrium) each month to prepare for fertilization LH stimulates corpus luteum to produce progesterone which is involved in the maintenance and development of the endometrium.

Ingestion

Intake of food; eating

Two types of refractory periods

absolute refractory period where no amount of stimulation can cause another action potential to occur relative refractory period - there must be greater than normal stimulation to cause and action potential because the membrane is starting from a potential that is more negative than its resting value

direct hormones

are secreted and then act directly on the target tissue ex: insulin

Neurotransmitters

chemical messengers that cross the synaptic gaps between neurons neurotransmission -NTs stored in membrane-bound vesicles in the nerve terminal - diffuse across synaptic cleft to bind to receptors - NTs brought back into the presynaptic neuron via reuptake - NTs may diffuse out of the synaptic cleft

Nerves and Tracts

nerves may carry more than one type of info; nerves are collections of neurons in the PNS tracts can only carry one type of info; tracts are collections of neurons in the CNS

induction

one group of cells influence the fate of nearyby cells

Punnett Square

diagrams that predict the relative genotypic and phenotypic frequencies that will result from the crossing of two individuals; the alleles of the two parents are arranged on the top and side of the square, with genotypes of the progeny represented at the intersections of these alleles the genotypes of the progeny will be the product of the two parental alleles

Bacterial growth curve

lag phase, log phase, stationary phase, death phase

chromosomal mutations

larger-scale mutations in which large segments of DNA are affected deletion mutations occur when a large segment of DNA is lost from a chromosome; small deletion mutations are considered frameshift mutations duplication mutations occur when a segment of DNA is copied multiple times in the genome inversion mutations occur when a segment of DNA is reversed within the chromosome insertion mutations occur when a segment of DNA is moved from one chromosome to another; small insertion mutations are considered frameshift mutations translocation mutations occur when a segment of DNA from one chromosome is swapped with a segment of DNA from another chromosome

accessory organs of digestion

liver, pancreas, gallbladder originate as an outgrowth of endoderm from the gut tube during development

WBCs: Agranulocytes

lymphocytes (specific immune response) and monocytes (phagocytize foreign matter) lymphocytes can be primary responders to infection and others function to maintain a long term memory bank of pathogen recognition lymphocyte maturation takes place in different locations 1. mature in bone marrow - B cells (responsible for antibody generation) 2. mature in thymus - T cells (kill virally infected cells and activate other immune cells) once monocytes leave the bloodstream and enter an organ, they are renamed macrophages -each organ's macrophage population may have a specific name as well (in the CNS they are called microglia; in the skin they are called LAngerhans cells; in the bone they are called osteoclasts)

two types of summation

temporal summation - multiple signals are integrated during a relatively short period of time spatial summation - the additive effects are based on the number and location of the incoming signals

gene mapping

the recombination frequency is the likelihood of two alleles being separated during crossing over in meiosis; genetic maps can be made using recombination frequency as the scale in centimorgans (one map unit/centimorgan corresponds to 1 percent change of recombination occurring between two genes)

simple twitch

the response of a single muscle fiber to a brief stimulus at or above the threshold stimulus and consists of a latent period, a contraction period, and a relaxation period the latent period is the time that the action potential spreads along the muscle and allows for calcium to be released from the SR the muscle then contracts, and, assuming calcium is cleared from the sarcoplasm, it relaxes

dihbyrid cross

we can extend a Punnett Square to account for the inheritance of two different genes using a dihybrid cross * remember that according to Mendel's law of independent assortment), the inheritance of one gene is independent of the inheritance of the other - this will hold true for unlinked genes, although it will be more complicated for linked genes this creates a 4x4 punnett square -if we cross two plants that are heterozygous for both traits, then the offspring will have a phenotypic ratio of 9:3:3:1 (9 tall and purple, 3 tall and white, 3 dwarf and purple, and 1 dwarf and white) - note that the 3:1 phenotypic ratio still holds for each trait, reflecting Mendel's second law

cleavage

the zygote undergoes rapid miotic cell division in a process called cleavage the first cleavage officially creates the embryo as it nullifies the zygote's unicellularity indeterminate cleavage results in cells that can still develop into complete organisms determinate cleavage results in cells with fates that are already determined (differentiation)

nephron function

two main goals of the kidney: keep what the body needs and lose what it doesn't; and concentrate the urine to conserve water nephron function revolves around the proximal convoluted tubule and the loop of henle

two types of neurons in the autonomic NS

two neurons work together to transmit messages from the spinal cord preganglionic neuron and postganglionic neuron the soma of the preganglionic neuron is in the CNS and its axon travels to a ganglion in the PNS - here it synapses on the cell body of the postganglionic neuron, which then stimulates the target tissue

supraspinal circuits

used in scenarios require input from the brain or brainstem

Test Cross

used to determine an unknown genotype in a test cross, the organism with an unknown genotype is crossed with an organism known to be homozygous recessive if all the offspring (100%) are of the dominant phenotype, then the unknown genotype is likely to be homozygous dominant if there is a 1:1 distribution of dominant to recessive phenotypes, then the unknown genotype is likely to be heterozygous because a test cross is used to determine the genotype of the parent based on the phenotypes of its offspring, test crosses are sometimes called back crosses

Hematocrit

percentage of blood volume occupied by red blood cells

the synapse

presynaptic neuron and postsynaptic neuron if a neuron signals to a gland or muscle, rather than another neuron, the postsynaptic cell is called an effector most synapses are chemical in nature (neurotransmitter)

recognition of self and nonself

self-antigens are the proteins and carbs present on the surface of every cell of the body -under normal circumstances, these self-antigens signal to immune cells that the cell is not foreign and should not be attacked -when the immune system fails to make the distinction between self and nonself, it may attack cells expressing particular self-antigens, a condition called autoimmunity - another problem arises when the immune system misidentifies a foreign antigen as dangerous when it is not - allergies like pet dander, pollen, and peanuts are not inherently threatening to human life but some people's immune systems are hypersensitive to these antigens and become overactivated when these antigens are encountered --> allergic reaction, hypersensitive reactions

Ohm's law applied to circulation

(change in) P=CO x TRP (change)P:pressure differential across the circulation CO: cardiac output TRP: total peripheral (vascular) resistance arterioles and capillaries act much like resistors in a circuit decreased resistance means increase in cardiac output

endocrine glands: anterior pituitary

- AP synthesizes and secretes seven different products: four of which are tropic hormones and the other three are direct hormones - FLAT (FSH, LH, ACTH, TSH) PEG (Prolactin, endorphins, GH) - prolactin stimulates milk production in the mammary glands; endorphins decrease the perception of pain; growth hormone promotes the growth of muscle and bone - GH prevents glucose uptake in certain tissues and stimulates the breakdown of fatty acids to increase the availability of glucose overall, allowing muscle and bones to use it

organs of the endocrine system

- Adrenal glands - Ovaries - Pancreas (islets of Langerhans) - Parathyroid glands - Pineal gland - Pituitary gland - Testes - Thymus gland - Thyroid gland

Pancreas

- has both exocrine and endocrine functions - exocrine tissues secrete substances directly into the ducts; the pancreas produces a number of digestive enzymes - from an endocrine standpoint, small clusters of hormone-producing cells are grouped together into islets of Langerhans throughout the pancreas --> they contain alpha, beta, or delta cells alpha cells secrete glucagon --> secreted in times of fasting when glucose levels are low; glucagon increases glucose production by triggering glycogenolysis, gluconeogenesis, and the degradation of protein and fat; certain gastrointestinal hormones increase glucagon from alpha cells; when blood glucose concentrations are high, glucagon is inhibited beta cells secrete insulin --> -antagonistic to glucagon; so it's secreted when blood glucose levels are high -insulin induces muscles and liver cells to take up glucose and store it as glycogen for later use -insulin stimulates anabolic processes such as fat and protein synthesis -in excess --> hypoglycemia; underproduction --> diabetes mellitus (hyperglycemia) delta cells secrete somatostatin --> inhibitor of insulin and glucagon secretion; high blood glucose and amino acid concentrations stimulate the secretion of somatostatin; it is produced by the hypothalamus where it decreases GH secretion in addition to its effects on insulin and glucagon

endocrine gland: thyroid

- the thyroid is controlled by the thyroid-stimulating hormone from the anterior pituitary -two major functions of the thyroid: setting basal metabolic rate and promoting calcium homeostasis; it mediates the first function by releasing triiodothyronine (T3) and thyroxine (T4), while it carries out the second function through the release of calcitonin

Cell Theory

-all living things are composed of cells -the cell is the basic functional unit of life -cells arise only from preexisting cells -cells carry genetic info in the form of DNA and this genetic material is passed on from parent to daughter cell

Growth Hormone (GH)

-bone originates in special regions of the bone known as epiphyseal plates, which seal shut during puberty -an excess of GH released in childhood (before this closure) can cause gigantism, and a deficit results in dwarfism -acromegaly: abnormal growth in the hands, feet, and head

calcium's functions

-bone structure and strength -release of NTs from neurons -regulation of muscle contraction -clotting of blood -role in cell movement and exocytosis of cellular materials

Cytotoxic immunity

-cell-mediated immunity -centered on the function of T-cells; they mature in the thymus where they undergo negative and positive selection -positive selection refers to allowing only the maturation of cells that can respond to the presentation of antigens on MHC -negative selection refers to the causing apoptosis in cells that are self-reactive (activated by proteins produced by the organisms itself) -the maturation of T cells is facilitated by thymosin; once the T cells leave the thymus, it is mature but naive- upon exposure to antigen, T cells will undergo clonal selection so that only those with the highest affinity for a given antigen proliferate there are three major types of T cells 1. helper T cells (Th) also called CD4+ T cells --> coordinate the immune response by secreting chemicals known as lymphokines (capable of recruiting other immune cells); the loss of these cells occurs in HIV infection and AIDs; CD4+ T cells respond to antigens presented on MHC II molecules- most effective against bacterial, fungal, and parasitic infections 2. cytotoxic T cells (Tc or CTL) also called CD8+ T cells --> are capable of directly killing virally infected cells by injecting toxic chemicals that promote apoptosis into the infected cell; responds to antigens presented on MHC-I molecules; most effective against viral infections and intracellular infections 3. Suppressor or regulatory T cells (Treg) --> also expresses CD4, but can be differentiated from helper T cells because they also express a protein called Foxp3 - these cells help to tone down the immune response once infection has been adequately contained; these cells also turn off self-reactive lymphocytes to prevent autoimmune diseases: self tolerance memory T cells can be generated - these cells lie in wait until the next exposure to the same antigen; when activated, they carry out a more robust and rapid response

Thermoregulation (Skin)

-cooling mechanisms include sweating, which absorbs heat from the body through evaporation of water from sweat, and vasodilation. Sweat glands are innervated by postganglionic cholinergic sympathetic neurons. -warming mechanisms include piloerection, in which arrector pili muscles contract, causing hairs to stand on end (trapping a layer of warmed air around the skin), vasoconstriction, shivering and insulation provided by fat

amino acid derivative hormones

-less common than peptide and steroid -derived from one or two amino acids, usually with a few additional modifications -important hormones include epinephrine, norepinephrine, triiodothyronine, and thyroxine -the chemistry of these hormones is less predictable -know that catecholamines (norepinephrine and epinephrine) bind to G protein-coupled receptors VS. thyroid hormones bind intracellularly

peptide hormones

-made up of amino acids -derived from larger polypeptides that are cleaved into smaller units (post-translational modification) -transported to Golgi apparatus for modification (activation) - they activate the hormones and direct them to the correct locations in the cell -packaged into vesicles and released by exocytosis -charged so they cannot pass through plasma membrane - the peptide hormone (first messenger) binds to an extracellular receptor (SURFACE receptor) and triggers transmission of a second signal (second messenger) -- type of receptor will determine what happens once the hormone has stimulated the receptor -common secondary messengers are cAMP, IP3, and calcium -the connection between the hormone at the surface and the effect brought about by second messengers within the cell is known as a signaling cascade; at each step there is the possibility of amplification - these peptide hormones have rapid and short lived effects, they act through transient 2nd messengers -Water soluble so they travel freely in bloodstream (do not require carriers) Have names that end in -in or -ine (insulin, vasopressin)

6 products secreted by stomach

1. HCl (kills microbes, denatures proteins, and converts pepsinogen into pepsin) 2. pepsinogen (cleaved in the stomach to pepsin; an enzyme that partially digests proteins) 3. mucus (protects mucosa) 4. bicarbonate (protects mucosa) 5. water (dissolves and dilutes ingested materials) 6. intrinsic factor (required for normal absorption of vitamin B12)

Composition of blood

55% liquid and 45% cells -plasma is the liquid portion of blood, an aq mixture of nutrients, salts, respiratory gases, hormones, and blood proteins -plasma can be further refined via the removal of clotting factors into serum -cellular portion of blood: erythrocytes, leukocytes, platelets -All blood cells are formed from hematopoietic stem cells which originate in bone marrow

Cells of the Adaptive Immune System

B cells govern the humoral response T cells mount the cell-mediated response all cells of the immune system are created in the bone marrow but B cells mature in the bone marrow and T cells mature in the thymus once we are exposed to a pathogen, it might take a few days for physical symptoms to be relieved because the adaptive immune system takes time to form specific defenses against pathogens

Thyroid: Calcitonin

C-cells produce calcitonin (c-cells are also called parafollicular cells) calcitonin decreases plasma calcium levels in three ways: 1. by increasing calcium excretion from the kidneys 2. by decreasing calcium absorption in the gut 3. by increasing storage of calcium in the bone high levels of calcium in the blood stimulate secretion of calcitonin from the C cells calciTONin TONes down calcium levels in the blood

Summary of Digestive Processes

Figure 9.5 in Kaplan (page 317)

absorption of carbohydrates and amino acids in the small intestine

Figure 9.7 in Kaplan (page 320)

absorption of lipids in small intestine

Figure 9.8 in Kaplan (page 321)

PNS (peripheral nervous system)

Made up of the nerve cells and their fibers that are outside the brain and spinal cord. Allows the brain and spinal cord to communicate with the rest of the body. includes all 31 pairs of spinal nerves and 10 of the 12 pairs of cranial nerves

intrapleural space

Space between the two membranes, visceral pleura and parietal pleura, that cover the lungs. contains a thin layer of fluid- helps lubricate the two pleural surfaces

Thyroid: T3, T4

T3 and T4 -both produced by the iodination of the amino acid tyrosine in the follicular cells of the thyroid (FOLLICULAR CELLS PRODUCE THYROID HORMONE) -the numbers refer to the number of iodine atoms attached to tyrosine -the thyroid is capable of resetting the basal metabolic rate of the body by making energy production more or less efficient, as well as altering the utilization of glucose and fatty acids -increased T3 and T4 will lead to increased cellular respiration: increasing the synthesis and degradation of proteins and fatty acids - high plasma levels of thyroid hormone will lead to decreased TSH and TRH synthesis; negative feedback prevents the secretion of T3 and T4 - hyperthyroidism: a deficiency of iodine or inflammation of the thyroid; thyroid hormones are secreted in insufficient amounts or not at all - cretinism: a deficiency of thyroid hormone in children at birth will cause intellectual disability and developmental delay - hyperthyroidism: an excess of thyroid hormone; vs. hypothyroidism

Capillaries

are vessels with a single endothelial cell layer and are so small that red blood cells must pass through the capillaries in a single-file line the thin wall allows for easier diffusion of gases (O2 and CO2), nutrients, and wastes interface for communication of the circulatory system with the tissues allow endocrine signals to arrive at their target tissues

the vasculature

arteries, arterioles, capillaries, venules, veins all blood vessels are lined with endothelial cells - helps maintain the vessel by releasing chemicals that aid in vasodilation and vasoconstriction; these cells also allow white blood cells to pass through the vessel wall and into the tissues during inflammatory response ; also released chemicals when damages that are involved in blood clots that repair the vessel and stop bleeding the same types of cells comprise the different vessels and arteries have much more smooth muscle than veins

oxygen exchange in blood

carried by hemoglobin when binds to the heme's iron central group - changes in its oxidation state oxidation reduction reaction partial pressure of oxygen - 70-100mmHg (found out from taking a sample from the blood arteries) oxygen saturation is the percentage of hemoglobin molecules carrying oxygen whereas the partial pressure of O2 is oxygen within blood oxygen comes into the lungs and diffuses into the alveolar capillaries oxygen binds to a heme group - induces a conformational change of the shape of the hemoglobin hemoglobin is now relaxed, and can take other oxygen atoms more easily (higher affinity) *positive feedback* same with leaving the hemoglobin - after one leaves, easy for the other three to leave double positive feedback system *** COOPERATIVE BINDING ***

cell migration, cell death, and regeneration

cell migration: cells must be able to disconnect from adjacent structures and migrate to their correct location apoptosis (programmed cell death) occurs at various times in development necrosis is the process of cell death in which a cell dies as a result of injury. in necrosis, internal substances can be leaked causing irritation of nearby tissues or even an immune response regenerative capacity is the ability of an organism to regrow certain parts of the body (varies from species to species); complete regeneration vs. incomplete regeneration (humans; newly formed tissue is not identical to the tissue injured or lost) senescence is biological aging

Bacterial Flagella

chemotaxis - detect chemical stimuli to move bacterial flagella are composed of a filament, basal body, and a hook.

lymphatic system structure

circulatory system that consists of one-way vessels with intermittent lymph nodes that move toward the center of the body -these vessels carry lymphatic fluid (lymph) and most join to form a large thoracic duct in the posterior chest, which then delivers the fluid into the left subclavian vein (near the heart) lymph nodes are small, bean-shaped structures along the lymphatic vessels - lymph nodes contain a lymphatic channel as well as an artery and vein - they provide a space for the cells of the immune system to be exposed to possible pathogens

cardiovascular system

consists of the heart, blood vessels, and blood heart - pumps and distributes blood through the vasculature (arteries, capillaries, and veins) after blood travels through veins, it is returned to the right side of the heart where it is pumped to the lungs to be reoxygenated then, the oxygenated blood returns to the left side of the heart where it is once again pumped to the rest of the body

function of respiratory system: control of pH

control pH through bicarbonate buffer system (know equation) when blood pH decreases (acidemia), respiration rate increases to compensate by blowing off CO2. this causes a LEFT shift in the buffer equation, reducing hydrogen ion concentration when blood pH increases (alkalemia), respiration rate decreases to compensate by trapping CO2. this causes a RIGHT shift in the buffer equation, increasing hydrogen ion concentration

digestion and absorption

digestion involves the breakdown of food into its constituent organic molecules: starches and other carbs into monosaccharides, lipids into free fatty acids and glycerol, and proteins into amino acids -digestion can be mechanical (the physical breakdown of large food particles into smaller food particles) or chemical (the enzymatic cleavage of chemical bonds) absorption involves the transport of products of digestion from the digestive tract into the circulatory system for distribution to the body's cells and tissues

Patterns of Evolution

divergent evolution refers to the independent development of dissimilar characteristics in two or more lineages sharing a common ancestor parallel evolution refers to the process whereby related species evolve in similar ways for a long period of time in response to analogous environmental selection pressures convergent evolution refers to the independent development of similar characteristics in two or more lineages not sharing a recent common ancestor

Pancreas (accessory organ)

endocrine functions: release of insulin, glucagon, and somatostatin - peptide hormones necessary for maintenance of proper blood sugar levels; the hormone function of the pancreas is limited to the cells residing in islets of Langerhans scattered throughout the organ the bulk of the pancreas is made of exocrine cells called acinar cells that produce pancreatic juices --> pancreatic amylase breaks down the large polysaccharides into small disaccharides (responsible for carb digestion; pancreatic peptidases (trypsinogen, chymotrypsinogen, and carboxypeptidases A and B) are released in their zymogen form but are activated and responsible for protein digestion; also produces pancreatic lipase which breaks down fats into fatty acids and glycerol pancreatic juices are transferred to the duodenum via a duct system that runs along the middle of the pancreas; acinar cells secrete their products into ducts (these ducts then empty into the duodenum through major and minor duodenal papillae)

Genetic Leakage

flow of genes between species; in some cases, individuals from different (but closely related) species can mate to produce hybrid offspring the hybrid carries genes from both parent species, so this can result in a net flow of genes from one species to another

Atrial natriuretic peptide (ANP)

hormone secreted from atrial cells of the heart; aids in the loss of salt within the nephron, acting as a natural diuretic with loss of fluid ANP is a fairly weak diuretic - some fluid is lost but not enough to counter the effects of a high-salt diet on BP

Divisions of the immune system

innate immunity is composed of defenses that are always active against infection but lack the ability to target specific invaders; and for this reason it is also called nonspecific immunity/nonspecific immune response adaptive immunity refers to the defenses that target a specific pathogen; this system is slower to act, but can maintain immunological memory of an infection to mount a faster attack in subsequent infections; specific immunity/specific immune response -has two divisions: humoral immunity (driven by B cells and antibodies) and cell-mediated immunity (driven by T cells)

diabetes mellitus

insulin is not secreted adequately or tissues are resistant to its effects diabetics often report polyuria (increased frequency of urination) and polydipsia (increased thirst) Type I (insulin-dependent) diabetes mellitus is caused by autoimmune destruction of beta cells in the pancreas, resulting in low or absent insulin production; require regular injections of insulin to prevent hyperglycemia Type II (non-insulin-dependent) diabetes mellitus is the result of receptor-level resistance to the effect of insulin; partially inherited and partially due to environmental factors (high-carb diets and obesity)

Functions of the respiratory system: immune function

multiple mechanisms, including vibrissae, mucous membranes, and the mucociliary escalator, help filter the incoming air and trap particulate matter lysozyme in the nasal cavity and saliva attacks peptidoglycan cell walls of gram-positive bacteria macrophages can engulf and digest pathogens and signal to the rest of the immune system that there is an invader mucosal surfaces are covered with IgA antibodies - help protect against pathogens that contact mucous membranes mast cells have antibodies on their surface that, when triggered, can promote the release of inflammatory chemicals; mast cells are often involved in allergic reactions as well

Oxygen debt and muscle fatigue

muscles require ATP to function -> slow twitch (red) fibers have high levels of mitochondria to use oxidative phosphorylation to make ATP: this means that high conc of oxygen are required to generate the large amount of ATP muscle cells needed there are two supplemental energy reserves in muscle -creatine phosphate is created by transferring a phosphate group from ATP to creatine during times of rest; this reaction can then be reversed during muscle use to quickly generate ATP from ADP -myoglobin is a heme-containing protein that is a muscular oxygen reserve oxygen debt: the difference between the amount of oxygen needed by the muscles and the actual amount present

WBCs: thrombocytes

platelets cell fragments or shards released from cells in bone marrow known as megakaryocytes their function is to assist in blood clotting and they are present in high conc. the production of blood cells and platelets is called hematopoiesis and is triggered by a number of hormones, growth factors, and cytokines -thrombopoietin is secreted by the liver and kidney and it stimulates mainly platelet development

distal convoluted tubule (DCT)

responsive to aldosterone and is a site of salt reabsorption and waste product excretion, like the PCT

pineal gland

secretes the hormone melatonin (involved in circadian rhythms); pineal gland receives projections directly from the retina but is not involved in vision --> decrease in light intensity releases melatonin

Mendel's Second Law: Law of Independent Assortment

states that the inheritance of one gene does not affect the inheritance of another gene allows for greater genetic diversity in offspring this second law has been complicated by the discovery of linked genes second law aligns with prophase I of meiosis

biometric techniques

statistical analysis of biological data used heavily in genetics ex. Punnett square, mapping of chromosomes with RF, Hardy Weinberg equilibrium

Thymosin

stimulates the maturation of lymphocytes into T cells of the immune system

theory of punctuated equilibrium

suggests that changes in some species occur in rapid bursts rather than evenly over time

blood antigens

surface proteins; in general, an antigen is any specific target to which the immune system can react two major antigen families for blood groups are the ABO antigens and the Rh factor

Cardiac Output (CO)

total blood volume pumped by a ventricle in a minute product of heart rate HR- beats per minute and stroke volume SV- volume of blood pumped per beat the two pumps are connected in series so the volumes of blood passing through each side must be the same *for humans the cardiac output is about 5 liters per min

bacterial genetic recombination

transformation: the integration of foreign genetic material into the host genome conjugation is the transfer of genetic material from one bacterium to another across a conjugation bridge; a plasmid can be transferred from F+ cells to F- cells, or a portion of the genome can be transferred from an Hfr cell to a recipient transduction is the transfer of genetic material from one bacterium to another by bacteriophage (viruses that can infect bacteria; they have tail sheaths that inject the genetic material and tail fibers that attach to the host cell)

Cells of the innate immune system: natural killer cells

type of nonspecific lymphocyte that is able to detect the downregulation of MHC and induce apoptosis in these virally infected cells; cancer cells may be downregulate MHC production so NK cells also offer protection from the growth of cancer as well the cell destroys the body's own cells that have become infected with pathogens

muscle contraction: relaxation

*Acetylcholine is degraded* in the synapse by the enzyme known as acetylcholinesterase. --> this results in termination of the signal at the neuromuscular junction and allows the sarcolemma to repolarize As the *signal decays*, calcium release ceases, and the SR takes up calcium from the sarcoplasm.--> the SR tightly controls the intracellular calcium conc so that muscles are contracted only when necessary *ATP* binds to the *myosin heads*, *freeing* them from actin. Once the myosin and actin disconnect, the sarcomere can return to its *original width*.

Stomach (Digestive System)

- (Humans) located in the upper left quadrant of the abdominal cavity, underneath the diaphragm - uses hydrochloric acid and enzymes to digest food (creates a harsh environment); its mucosa is quite thick to prevent autodigestion (the mucosa contains gastric glands and pyloric glands) - the stomach can be divided into: the fundus and the body (which contain mostly gastric glands); the antrum and pylorus (which contain mostly pyloric glands); the internal curvature is called the lesser curvature; and the external curvature is called the greater curvature - the lining of the stomach is thrown into folds called rugae - the gastric glands respond to signals from the vagus nerve of the parasympathetic system which is activated by the brain in response to sight, taste, and smell of food - 3 types of gastric glands - pepsin digests proteins by cleaving peptide bonds near aromatic amino acids (active in a low pH environment) via parietal and chief cells - pyloric glands contain G cells that secrete gastrin (peptide hormone): it induces the parietal cells in the stomach to secrete more HCl and signals the stomach to contract, mixing its contents -chyme is the acidic semifluid mixture of food particles in the stomach

Lung Capacities and Volumes

- Determined using spirometry equipment - Reserve of tidal volume at rest allows increase in tidal volume during maximal exercise. commonly tested lung volumes: -total lung capacity -residual volume -vital capacity -tidal volume -expiratory reserve volume -inspiratory reserve volume

Structure of antibodies

- Y-shaped proteins that have two heavy chains and 2 light chains - disulfide linkages and noncovalent interactions hold the heavy and light chains together -each antibody has an antigen-binding region at the end of which is called the variable region (domain), at the tips of the Y; and within this region there are specific polypeptide sequences that will bind only one specific antigen sequence - part of the reason for why the response takes a while is that each B cell undergoes hypermutation of its antigen-binding region, trying to find the best match for the antigen; only those B cells that can bind the antigen with high affinity will survive, providing a mechanism for generating specificity called clonal selection -the rest of the antibody molecule is called constant region (domain) - NK cells, macrophages, monocytes, and eosinophils have receptors for this region; and it can initiate the complement cascade - each B cell makes only one type of antibody, but we have many B cells so our immune system recognizes many antigens -antibodies come in five different isotypes (IgM, IgD, IgG, IgE, and IgA) -cells can change which isotype of antibody they produce when stimulated by specific cytokines in a process called isotype switching - a hinge between the arms and stem make the arms flexible

Liver (accessory organ)

- bile ducts connect the liver with both the gallbladder and small intestine; bile is produced in the liver and travels down the bile ducts to where it might be stored in the gallbladder or secreted into the duodenum - the liver also receives all blood draining from the abdominal portion of the digestive tract through the hepatic portal vein; this nutrient rich blood can be processed by the liver before draining into the inferior vena cava on its way to the right side of the heart - the liver synthesizes and produces nutrients (glycogenesis and glycogenolysis; storage and mobilization of fats; gluconeogenesis) - the liver detoxifies both endogenous compounds and exogenous compounds - production of urea - production of bile (bilirubin travels to the liver, where it is conjugated- attached to a protein, and secreted into the bile for excretion) - if the liver is unable to process or excrete bilirubin, then jaundice or yellowing of the skin may occur - the liver also produces proteins necessary for proper body functioning --> albumin maintains plasma oncotic pressure and also serves as a carrier for many drugs and hormones, and clotting factors used during blood coagulation

atrial natriuretic peptide (ANP)

- endocrine hormone (peptide) -released by heart when cells in atria are stretched from excess blood volume - regulates salt and water balance -promotes excretion of sodium and increases urine volume - lowers blood pressure and volume; no effect on blood osmolarity -functionally antagonistic to aldosterone

the heart

- four-chambered structure composed predominantly of cardiac muscle - the heart is composed of two pumps supporting two different circulations in series - the right side of the heart accepts deoxygenated blood returning from the body and moves it to the lungs by way of the pulmonary arteries (the first pump, pulmonary circulation) - the left side of the heart receives oxygenated blood from the lungs by way of the pulmonary veins and forces it out to the body through the aorta (second pump, systemic circulation) each side of the heart consists of an atrium and a ventricle - the atria are thin walled structures where blood is received either from the venae cavae (deoxygenated blood entering the right heart) or the pulmonary veins (oxygenated blood entering the left heart); the atria contract to push blood into the ventricles - after the ventricles fill, they contract to send blood to the lungs (right ventricle) and the systemic circulation (left ventricle) - the ventricles are far more muscular than the atria, allowing for more powerful contractions that are needed to push blood through the rest of the body the atria are separated from the ventricles by the atrioventricular valves; the ventricles are separated from the vasculature by the semilunar valves --> these valves allow the heart muscle to create the pressure within the ventricles necessary to propel the blood forward within the circulation, while also preventing backflow of blood the valve between the right atrium and the right ventricle is known as the tricuspid valve (three leaflets) the valve between the left atrium and left ventricle is known as the mitral or bicuspid valve (two leaflets) the valve that separates the right ventricle from the pulmonary circulation is known as the pulmonary valve, while the valve that separates the left ventricle from the aorta is known as the aortic valve (both semilunar valves have three leaflets)

Starling forces

- hydrostatic and oncotic pressures -balance of these forces maintains proper fluid volumes & solute concentrations inside & outside the vasculature -Imbalance of these pressures results in too little or too much fluid in tissues the movement of solutes and fluids at the capillary level is governed by pressure differentials (just like the movement of carbon dioxide and oxygen in the lungs)

milk ejection

- infant latches on to breast -nipple stimulation causes activation of hypothalamus -oxytocin is released from posterior pituitary leading to contraction of smooth muscle of breast and milk ejection -hypothalamus stops releasing dopamine on anterior pituitary allowing prolactin release (produces milk and regulates milk supply)

Rh factor

- surface protein expressed on red blood cells *Rh+ and Rh- refer to presence or absence of a specific allele called D (can be dictated by a plus or minus sign on ABO blood type: ex is O+) *Rh+ is dominant so if present, it is expressed; Rh negative individual will only create anti-Rh antibodies after exposure to Rh-positive blood *If a woman is Rh+ and her fetus is Rh-, her immune system will make antibodies against it *Not a problem for 1st child b/c mother starts producing the antibodies after the child is born *Any subsequent pregnancies in which fetus is Rh+ will be problematic b/c maternal anti-Rh antibodies can cross the placenta and attack fetal blood cells (erythroblastosis fetalis (fatal) ) -Avoided by giving the Rh- mother Rh-immunoglobulin during pregnancy & immediately after delivery *immunoglobulin absorbs the fetus's Rh+ cells preventing production of anti-Rh antibodies by mother

Modes of Natural Selection

-Stabilizing selection: keeps phenotypes within a specific range by selecting against extreme phenotypes (eg: human birth weight is maintained within a narrow band by stabilizing selection; fetuses that weigh too little may not be healthy enough to survive, and fetuses that weight too much may experience trauma during delivery -- it is advantageous to keep birth weights within a narrow range) -Directional selection: developed from adaptive pressures; shifting toward a new standard phenotype (eg: development of antibiotic resistance in a species of bacteria overtime) -Disruptive selection: two extreme phenotypes are selected over the norms (ex: galapagos finches); disruptive selection is facilitated by the existence of polymorphisms (naturally occurring differences in form between members of the same population); adaptive radiation is a related concept that describes the rapid rise of a number of different species from a common ancestor (allows for various species to occupy different niches) niche - a specific environment, including habitat, available resources, and predators, for which a species is specifically adapted; adaptive radiation is favored by environmental changes or isolation of small groups of the ancestral species

steroid hormones

-derived from cholesterol -produced by gonads and adrenal cortex -can easily cross the cell membrane because steroid hormones are derived from nonpolar molecules -INFLUENCES CELL BEHAVIOR BY MODIFYING TRANSCRIPTION -Bind to intracellular receptors or intranuclear; upon binding to the receptor, the steroid hormone-receptor complex undergoes conformational changes and then can bind to DNA to alter gene transcription (decreasing or increasing) -dimerization is one common form of conformational change: pairing of two receptor-hormone complexes -Slower and longer lived (have direct actions on DNA) -Not water soluble --> must be carried by proteins in bloodstream --> inactive while attached to carrier protein (must dissociate from carrier to function) -Have names that end in -one, -ol, or -oid (testosterone, cortisol, glucocorticoids)

measuring evolutionary time

-evolution is a slow process, featuring changes in the environment and subsequent changes in genotypes and phenotypes of a population over time -the rate of evolution is measured by the rate of change of a genotype over a period of time and is related to the severity of the evolutionary pressures put on the species molecular clock model: the degree of difference in the genome between two species is related to the amount of time since the two species broke off from a common ancestor

adrenal medulla

-nestled inside the adrenal cortex - production of sympathetic hormones epinephrine and norepinephrine; the specialized nerve cells in the medulla are capable of secreting these compounds directly into the bloodstream - both of these sympathetic hormones are amino-acid derivatives that belong to a class of molecules called catecholamines -involved in fight or flight response - epinephrine can increase the breakdown of glycogen into glucose (glycogenolysis) in both the liver and muscle; and increase basal metabolic rate -both hormones will increase heart rate, dilate the bronchi, and shunt blood flow to the systems that would be used in sympathetic response (there is vasodilation of blood vessels too)

oral cavity (digestion)

-plays a role in mechanical and chemical digestion -mechanical digestion in the mouth involves breaking up the food particles using teeth, tongue, and lips (mastication = chewing); chewing helps increase the surface area to volume ratio of food, creating more surface area for enzymatic digestion -chemical digestion vis saliva produced by three pairs of salivary glands; aids in mechanical digestion by moistening and lubricating the food -- salivary glands are innervated by the parasympathetic NS -salivation is triggered by food in the oral cavity and when food is near; saliva contains salivary amylase (lipase/ptyalin) that is capable of hydrolyzing starch into smaller sugars while lipase hydrolyzes lipids -our tongue forms the food into a bolus, which is forced back to the pharynx and swallowed

tropic hormones

-require an intermediate to act - usually originate in the brain or anterior pituitary gland b/c these structures are involved in coordination of processes within the body -cause release of another hormone at the organ level -GnRH causes release of FSH and LH which act on the gonads (testes and ovaries) -CRF causes release of ACTH which acts on the adrenal cortex -TRH causes release of TSH which acts on the thyroid

ABO antigens

-the A and B alleles are codominant, while the O allele is recessive -an individual has antibodies for any ABO alleles he does not have - O is the universal donor; AB is the universal recipient giving the wrong blood type in a transfusion would lead to rapid hemolysis (rupture of blood cells)

endocrine glands: posterior pituitary

-the PP contains the nerve terminals of neurons with cell bodies in the hypothalamus; the PP receives and stores ADH and oxytocin (produced by the hypothalamus) -ADH is secreted in response to low blood volume or increased blood osmolarity; its action is at the level of the collecting duct where it increases the permeability of the duct to water; this increases the reabsorption of water, which results in increased blood volume and higher blood pressure -oxytocin allows for coordinated contraction of uterine smooth muscle; may be involved in bonding behavior; has a POSITIVE FEEDBACK LOOP (the release of oxytocin promotes uterine contraction, which promotes more oxytocin release)

hypothalamus interactions with anterior pituitary

-the hypothalamus secretes compounds into the hypophyseal portal system which is a blood vessel system that directly connects the hypothalamus with the anterior pituitary; once released from the hypothalamus into this portal bloodstream, the hormones travel down the pituitary stalk and bind to receptors in the anterior pituitary, stimulating the release of other hormones -the hypothalamus secretes several different tropic hormones and the anterior pituitary secretes other hormone(s) in response: GnRH --> FSH and LH GHRH --> GH TRH --> TSH CRF --> ACTH - one exception is prolactin-inhibiting factor (PIF; actually dopamine) is released by the hypothalamus and causes a decrease in prolactin secretion - each of the tropic hormones then causes a release of another hormone from an endocrine gland that has negative feedback effects (ex: CRF from hypothalamus to ACTH from ant. pituitary to cortisol from adrenal cortex)

hypothalamus interactions with the posterior pituitary

-the posterior pituitary does not receive tropic hormones through the hypophyseal portal system; rather, neurons in the hypothalamus send their axons down the pituitary stalk directly into the posterior pituitary, which then can release oxytocin and antidiuretic hormone -oxytocin stimulates uterine contractions during labor -antidiuretic hormone (ADH also called vasopressin) increases reabsorption of water in the collecting ducts of the kidneys; ADH is secreted in response to increases plasma osmolarity, or increased concentration of solutes within the blood

Mitosis

2 identical daughter cells are created from a single cell; this process occurs in SOMATIC cells (NOT in reproductive cells) prophase: chromosomes condense and spindle forms; nuclear membrane dissolves allowing spindle fibers to contact chromosomes metaphase: chromosomes align along the metaphase plate (equatorial plate) anaphase: sister chromatids separate telophase: new nuclear membranes form (reverse of prophase); then cytokinesis occurs

gastric glands of stomach

3 types: 1. mucous cells produce bicarbonate rich mucus that protects the muscular wall from harshly acidic (pH = 2) and proteolytic environment of the stomach 2 & 3. gastric juice is a combination of the secretions from the other two types of cells in the gastric glands: chief cells and parietal cells - chief cells secrete pepsinogen (inactive form of pepsin) - parietal cells secrete Hydrogen ions as HCl and it cleaves pepsinogen to pepsin; also secretes intrinsic factor (a glycoprotein involved in the proper absorption of vitamin B12)

gene pool

All the genes, including all the different alleles for each gene, that are present in a population at any one time

blood pressure (BP)

BP must be kept sufficiently high to propel blood forward; blood pressure provides info about the circulatory system BP is a measure of force per unit area exerted on the wall of the blood vessels measured with a sphygmomanometer - measures the gauge pressure in systemic circulation, which is the pressure above and beyond atm BP is expressed as a ratio of the systolic (ventricular contraction) to diastolic (ventricular relaxation) pressures pressure gradually drops from the arterial to venous circulations with the largest drop occurring across the arterioles normal BP is between 90/60 and 120/80 BP is regulated using baroreceptors in the walls of the vasculature; these are specialized neurons that detect changes in the mechanical forces on the walls of the vessel Chemoreceptors regulate osmolarity

prokaryotic domains

Bacteria and Archaea Archaea -contain genes and several metabolic pathways that are similar to eukaryotes -have the ability to use alternative sources of energy -both archaea and eukaryotes start translation with methionine, contain similar RNA polymerases, and associate their DNA with histones -archaea contain a single circular chromosome, divide by binary fission or budding, and share a similar overall structure to bacteria -archaea are very resistant to many antibiotics bacteria -contains a cell membrane and cytoplasm; may have flagella or fimbriae - many antibiotics target the bacterial ribosome -can be mutualistic symbiotes, pathogens, or parasites

Arteries

Blood vessels that carry blood away from the heart to lungs and other parts of the body; largest of which is the aorta in systemic circulation; most arteries contain oxygenated blood; highly muscular and elastic, creating tremendous resistance to the flow of blood --> this is why the left heart must generate much higher pressures to overcome the resistance caused by systemic arteries only the pulmonary arteries and umbilical arteries contain deoxygenated blood smaller, muscular arteries are arterioles after arteries are filled with blood, the elastic recoil from their walls maintains a high pressure and forced blood forward

Shifts in the Oxyhemoglobin Dissociation Curve

Causes of a right shift of the oxyhemoglobin curve: "*Exercise* is the *right* thing to do." The following occur during exercise: -Increased PaCO2. -Increased [H+] (decreased pH). -Increased temperature. ---- a left shift may occur due to decreased PaCO2, decreased [H+] (increased pH), decreased temp, and decreased 2,3-BPG (fetal Hb has a higher affinity for oxygen than adult Hb so therefore it has a left-shifted curve compared to adult Hb)

immovable joints

Consist of bones that are fused together to form sutures or similar fibrous joints. Found primarily in the head, where they anchor bones of the skull together.

The Cell Cycle

G1: pre synthetic gap; creates organelles for energy and protein production; increases in size; must pass the restriction point to get to S, this is the G1/S checkpoint that checks if the DNA is in good enough condition S: synthesis of DNA; replicates genetic material: each chromosome consists of two identical chromatids bound at the centromere G2: postsynthetic gap; passes another quality checkpoint (G2/M) to see if it's a good size and has enough organelles M: mitosis and cytokinesis (splitting of the cytoplasm and organelles); prophase, metaphase, anaphase, telophase CDK-cyclin complexes can phosphorylate transcription factors to promote transcription of genes for the next stage

MHC II

MHC class II molecules are mainly displayed by professional antigen-presenting cells like macrophages - remember that these phagocytic cells pick up pathogens from the environment, process them, and then present them on MHC-II an antigen is a substance, usually a pathogenic protein, that can be targeted by an antibody the innate immune system also presents antigens because these antigens originated from outside the cell, the MHC-II pathway is usually referred to as the exogenous pathway the presentation of an antigen by an immune cell may result in the activation of both innate and adaptive immune systems professional antigen-presenting cells include macrophages, dendritic cells in the skin, some B cells, and certain activated epithelial cells -macrophages and dendritic cells also have special receptors known as pattern recognition receptors (PRR), the best-described of which are toll-like receptors -PRRs can recognize the category of the invader; this allows for the production of the appropriate cytokines to recruit the right type of immune cells

Bacterial (Extracellular Pathogen) Infections

Macrophages engulf bacteria and release inflammatory mediators; these cells also digest bacteria and present antigens from the pathogens on their surface in conjunction with MHC II cytokines attract inflammatory cells (including neutrophils and additional macrophages) mast cells are activated by inflammation and degranulate, resulting in histamine release and increased leakiness of capillaries the dendritic cells then leaves the affected tissue and travels to the nearest lymph node, where it presents the antigen to B cells. B cells that produce the correct antibody proliferate through clonal selection to create plasma and memory cells antibodies then travel through the bloodstream to the affected tissue, where they tag the bacteria for destruction CD4+T cells are activated and these cells come in two types Th1 and Th2 -Th1 cells release interferon gamma which activates macrophages and increases their ability to kill bacteria -Th2 cells help activate B cells and are more common in parasitic infections after the pathogen has been eliminated, plasma cells die, but memory B and T cells remain - they allow for a much faster secondary response at a later time

impulse propagation

Movement of an action potential down an axon, resulting in neurotransmitter release at the synaptic bouton and transmission of the impulse to the target neuron or organ action potentials are propagated down the axon when proximal sodium channels open and depolarize the membrane, inducing distal sodium channels to open as well; because of the refractory character of these channels, the action potential can move in only one direction myelin maximizes the speed of transmission - prevents the dissipation of the electrical signal; the insulation is so effective that the membrane is only permeable to ion movement at the nodes of Ranvier - the signal jumps from node to node (saltatory conduction)

Blood flow through the heart

Right atrium, right atrioventricular (tricuspid) valve, right ventricle, pulmonary semilunar valve, pulmonary artery, lungs (gas exchange), pulmonary veins, left atrium, left atrioventricular (mitral) valve, left ventricle, aorta, arteries, arterioles, capillaries, venules, veins, venae cavae, right atrium

digestive enzymes

Table 9.1 in Kaplan (page 316)

Support for DNA as genetic material

The Griffith experiment demonstrated the transforming principle, converting non-virulent live bacteria into virulent bacteria by exposure to heat-killed virulent bacteria the Avery-MacLeod-McCarty experiment demonstrated that DNA is the genetic material because degradation of DNA led to the cessation of bacterial transformation The Hershey-Chase experiment confirmed that DNA is the genetic material because only radiolabeled DNA could be found in bacteriophages

Neuralation

The formation of the nervous system during weeks 5-8 of gestation. Neurulation begins when a section of the ectoderm invaginates and pinches off to form the neural groove, which ultimately forms the neural tube, from which the brain and spinal cord develop. first, a rod of mesodermal cells known as the notochord forms along the long axis of the organism like a primitive spine. the notochord induces a group of overlying ectodermal cells to slide inward to form neural folds, which surround a neural groove. the neural folds grow towards one another until they fuse into a neural tube, which gives rise to the central NS. at tip of each neural fold are neural crest cells- these cells migrate outward to form the peripheral NS as well as specific cell types in other tissues the ectodermal cells will migrate over the neural tube and crest to cover the rudimentary NS.

enteric nervous system

The nervous system of the gastrointestinal tract. The neurons line the walls of the digestive tract and trigger peristalsis (rhythmic contractions) of the gut tube in order to move materials through the system the system can function without input from the brain and spinal cord; it is heavily regulated by the autonomic NS the parasympathetic NS is involved in stimulation of digestive activities, increasing secretions from exocrine glands and promoting peristalsis the sympathetic division is involved in the inhibition of these activities

Blastulation

The process by which a morula develops into a blastula with a fluid-filled cavity called a blastocoel. - contains two cell groups: 1. trophoblast cells that give rise to the chorion and the placenta 2. inner cell mass gives rise to the organism itself

Bohr effect

The tendency of certain factors to stabilize the hemoglobin in the tense conformation, thus reducing its affinity for oxygen and enhancing the release of oxygen to the tissues. The factors include increased PCO2, increase temperature, increased bisphosphoglycerate (BPG), and decreased pH. Note that the Bohr effect shifts the oxyhemoglobin saturation curve to the right. greater unloading of oxygen to the tissues

Viral (Intracellular Pathogen) Infections

Virally infected cell will begin to produce interferons, these reduce the permeability of nearby cells, reduce the rate of transcription and translation in these cells, and cause systemic symptoms. (also reduces the ability of the virus to infect these cells and decreases the ability of the virus to multiply) They present intracellular proteins on their surface in conjunction with MHCI in a virally infected cell. CD8 will recognize the MHC I and antigen complex as foreign and will inject toxins into the cell to promote apoptosis. The infection can shut down before it is able to spread to nearby cells in the event that the virus downregulates the production and presentation of MHC I molecules, natural killer cells will recognize the absence of MHC I and will accordingly cause apoptosis of these cells once the pathogen has been cleared, memory T cells will be generated that it can allow a faster response for the second exposure

male sexual development

Y chromosome allows for androgen production, resulting in male differentiation Androgen production low during infancy/childhood Testosterone, produced by the testes, increases dramatically during puberty, and sperm production begins. FSH stimulates Sertoli cells for sperm maturation LH causes interstitial cells to produce testosterone testosterone exerts negative feedback on hypothalamus and anterior pituitary to limit its own production to appropriate levels

mutations

a change in DNA sequence, results in a mutant allele mutant alleles can be contrasted with their wild-type counterparts, which are alleles that are considered "normal" or "natural" and are ubiquitous in the study population mutations can occur in a variety of ways substances that cause mutations are called mutagens elements known as transposons can insert and remove themselves from the genome; if a transposon inserts in the middle of a coding sequence, the mutation will disrupt the gene flawed proteins can arise in ways without an underlying change in DNA sequence: incorrect pairing of nucleotides during transcription/translation, or a tRNA molecule charged with the incorrect AA for its anticodon, can result in derangements of the normal amino acid sequence

deep vein thrombosis (DVT)

a clot in the deep veins of the leg; the clot may become dislodged and travel through the right heart to the lungs, where it can cause a life-threatening condition called a pulmonary embolus

monohybrid cross

a cross in which only one trait is being studied is called monohybrid the parent or P generation refers to the individuals being crossed; the offspring are filial or F generation -multiple generations can be denoted F generations by using numeric subscripts key concept: crossing two heterozygotes for a trait with complete dominance results in a 1:2:1 ratio of genotypes and a 3:1 ratio of phenotypes!!! *** (1 PP, 2 Pp, 1 pp; 3 Purple, 1 White)

renin-angiotensin-aldosterone system

a hormone cascade pathway that helps regulate blood pressure and blood volume

inclusive fitness

a measure of an organism's success in the population, based on the number of offspring, success in supporting offspring, and the ability of offspring to then support others inclusive fitness promotes the idea that altruistic behavior can improve the fitness and the success of a species as a whole

adrenal glands

a pair of endocrine glands that sit just above the kidneys and secrete corticosteroids (three functional classes: glucocorticoids, mineralocorticoids, and cortical sex hormones) 1. glucocorticoids -steroid hormones that regulate glucose levels -affect protein metabolism -MCAT tests on cortisol and cortisone --> these hormones raise blood glucose by increasing gluconeogenesis and decreasing protein synthesis; both can decrease inflammation and immunologic responses -cortisol is known as the stress hormone, it increases blood sugar and provides a ready source of fuel in case the body must react quickly in a dangerous situation -glucocorticoid release is under the control of ACTH which is secreted by the anterior pituitary (and ACTH is under the control of CRF from the hypothalamus) 2. mineralocorticoids - used in salt and water homeostasis; their most profound effects on the kidneys -aldosterone increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron; water follows the sodium cations into the bloodstream and this increases blood volume and pressure; since water and sodium ions flow together, plasma osmolarity remains unchanged (this is in contrast to ADH); aldosterone decreases the reabsorption of potassium and hydrogen ions in the same segments of the nephron, promoting their excretion in urine -aldosterone is under the control of renin-angiotensin-aldosterone system: decreased blood pressure causes juxtaglomerular cells of the kidney to secrete renin, which cleaves an inactive plasma protein, angiotensinogen, to its active form angiotensin I -- angiotensin I is then converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs -- angiotensin II stimulates to adrenal cortex to secrete aldosterone --> once blood pressure is restored, there is a decreased drive to stimulate renin release, thus serving as the negative feedback mechanism for this system 3. cortical sex hormones - androgens and estrogens the three S's of corticosteroids: salt (mineralocorticoids), sugar (glucocorticoids) and sex (cortical sex hormones)

Speciation

a species is defined as the largest group of organisms capable of breeding to form fertile offspring; the formation of a new species through evolution is called speciation reproductive isolation (which means progeny of separated populations can no longer freely interbreed) can occur pre zygotically or post zygotically - prezygotic mechanisms prevent formation of the zygote completely (temporal isolation: breeding at different times; ecological isolation: living in different niches; behavioral isolation: a lack of attraction between members; reproductive isolation: incompatible reproductive anatomy; gametic isolation (intercourse can occur but fertilization cannot) - post zygotic mechanisms allow for gamete fusion but yield nonviable or sterile offspring (hybrid inviability: formation of a zygote that cannot develop to term; hybrid sterility: forming hybrid offspring that cannot reproduce; and hybrid breakdown: forming first generation hybrid that are viable and fertile but second generation offspring are inviable and infertile)

immunization

active immunity: the immune system is stimulated to produce antibodies against a specific pathogen; the means by which we are exposed to this pathogen may be natural or artificial (natural: antibodies are generated by B cells once an individual becomes infected; artificial through vaccines) passive immunity: results from the transfer of antibodies to an individual; the immunity is transient because only the antibodies, and not the plasma cells that produce them, are given to the individual; examples: the transfer of antibodies across the placenta during pregnancy

modern synthesis model (neo-Darwinism)

adds knowledge of genetic inheritance and changes in the gene pool to Darwin's original theory when mutation or recombination results in a change that is favorable to the organism's reproductive success, that change is more likely to pass onto the next generation; the opposite is also true - this process is called differential reproduction over time, those traits passed on by more successful organisms will become ubiquitous in the gene pool; because the gene pool changes over time, it is important to note that populations evolve, NOT individuals

Teratogens

agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm they interfere with development

Anatomy of breathing

air enters nares and through the nasal cavity, where it is filtered by mucous membranes and nasal hairs (vibrissae) next, air passes into the pharynx (common pathway for lungs and food destined for esophagus) and the larynx (only a pathway for air) -- to keep food out of the respiratory tract, the larynx opening is covered by the epiglottis during swallowing; the larynx has two vocal cords then, air passes into the trachea and then into one of the two mainstem bronchi - the bronchi and trachea contain ciliated epithelial cells to catch material that has made it past the mucous membranes in the nose and mouth in the lungs, the bronchi continue to divide into smaller structures called bronchioles, which divide further into alveoli where gas exchange occurs. each alveolus is coated with surfactant, a detergent that lowers the surface tension and prevents it from collapsing - a network of capillaries surrounds each alveolus to carry oxygen and carbon dioxide -- large SA for gas exchange the lungs are contained in the thoracic cavity, which also contains the heart. membranes known as pleurae surround each lung; the pleurae forms a closed sac against which the lung expands; the surface adjacent to the lung is the visceral pleura, and the outer part is the parietal pleura * the lungs do not fill passively; they require skeletal muscles to generate the negative pressure for expansion * the most important of these muscles is the diaphragm, a thin muscular structure that divides the chest cavity from the abdominal cavity; under somatic control even though breathing is under autonomic control

MHC I

all nucleated cells display MHC class I molecules any protein produced within a cell can be loaded onto MHC-I and presented on the surface of the cell; this allows the immune system to monitor the health of these cells and to detect if the cells have been infected with a virus or another intracellular pathogen only those cells that are infected would be expected to present an unfamiliar (nonself) protein on their surfaces the MHC-I pathway is often called the endogenous pathway because it binds antigens that come from inside the cell

glial cells

also called neuroglia; play supportive and structural roles for neurons astrocytes: nourish neurons and form the blood-brain barrier, which controls the transmission of solutes from the bloodstream into nervous tissue ependymal cells: line the ventricles of the brain and produce CSF, which physically supports the brain and serves as a shock absorber microglia are phagocytic cells that ingest and break down waste products and pathogens in the CNS oligodendrocytes (CNS) and Schwann cells (PNS) produce myelin around axons

skeletal structure

axial skeleton: consists of the skull, vertebral column, ribcage, and hyoid bone (a small bone in the anterior neck used for swallowing); provides the basic framework of the body appendicular skeleton consists of the bones of the limbs (humerus, radius and ulna, carpals, metacarpals, and phalanges in the upper limb; and femur, tibia and fibula, tarsals, metatarsals, and phalanges in the lower limb); the pectoral girdle (scapula and clavicle); and pelvis both skeleton types are covered by other structures (muscles, connective tissue, and vasculature) the skeleton is created from two major components: the bone and cartilage

digestive tract

begins with the oral cavity (mouth) followed by the pharynx (a shared pathway for both food entering the digestive system and air entering the respiratory system); then the food enters the esophagus, which transports it to the stomach; then it travels to the small intestine then the large intestine; waste products of digestion enter the rectum, where feces are stored until an appropriate time of release salivary glands, the pancreas, liver, and gallbladder help to provide the enzymes and lubrication necessary to aid in the digestion of food

Hematopoiesis

blood cell formation; occurs in red bone marrow

superior vena cava and inferior vena cava

blood returns to the heart from the body via the venae cavae SVC returns blood from the portions of the body above the heart IVC returns blood from the portions of the body below the heart

portal systems

blood will pass through two capillary beds in series before returning to the heart; there are three portal systems hepatic portal system, blood leaving capillary beds in the walls of the gut passes through the hepatic portal vein before reaching the capillary beds in the liver hypophyseal portal system, blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituitary to allow for paracrine secretion of releasing hormones renal portal system, blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta

Penetrance and Expressivity

both reveal the complex interplay between genes and the environment penetrance is a population measure defined as the proportion of individuals in the population carrying the allele who actually express the phenotype (it is the probability that, given a particular genotype, a person will express the phenotype) - alleles can be classified by their degree of penetrance - individuals with more than 40 sequence repeats have full penetrance - (100% of individuals with this allele show symptoms of Huntington's disease) - individuals with fewer sequence repeats shoe high penetrance, wherein most (but not all) of those with the allele show symptoms of the disease - with fewer sequence repeats, the gene comes to have reduced penetrance, low penetrance, or even nonpenetrance expressivity is defined as varying phenotypes despite identical genotypes - if expressivity is constant, then all individuals with a given genotype express the same phenotype - if expressivity is variable, then individuals with the same genotype may have different phenotypes

regulation of breathing

breathing requires input from our nervous control center; breathing is primarily regulated by a collection of neurons in the medulla oblongata called the ventilation center that fire rhythmically to cause regular contraction of respiratory muscles these neurons contain chemoreceptors that are primarily sensitive to carbon dioxide -as the partial pressure for Co2 in blood rises (hypercarbia or hypercapnia), the respiratory rate will increase so that more CO2 is exhaled, causing CO2 levels in the blood to fall -these cells also respond to changes in oxygen conc - in significant situations of low oxygen (hypoxemia) we can, to a limited extent, control our breathing consciously

sphincter

circular smooth muscles around the canal that can contract to allow compartmentalization of function

Coagulation

clots are composed of blood coagulation factors (proteins) and platelets, and they prevent (or at least minimize) blood loss when the endothelium of a blood vessel is damaged, it exposes the underlying connective tissue, which contains collagen and a protein called tissue factor when platelets come into contact with exposed collagen, they sense this as evidence of injury --> in response, they release their contents and begin to aggregate; coagulation factors also sense tissue factor and initiate a complex activation cascade the end point of the activation cascade is the activation of prothrombin to form thrombin by thromboplastin thrombin can then convert fibrinogen into fibrin (which ultimately forms small fibers that aggregate and cross-link into a woven structure that captures RBCs and other platelets - forming a stable clot over the area of damage) a clot that forms on a surface vessel that has been cut is called a scab *ultimately, the clot will have to be broken down- this is done by plasmin, which is generated by plasminogen

macroscopic bone structure

compact done: dense and strong spongy (cancellous) bone; the lattice structure is visible under microscopes and consists of bony spicules (points) known as trabeculae -the cavities between trabeculae are filled with bone marrow (red marrow is filled with hematopoietic stem cells, which are responsible for the generation of all the cells in our blood; yellow marrow is composed primarily of fat and is relatively inactive) bones in the appendicular skeleton are typically long bones (characterized by cylindrical shafts called diaphyses that swell at each end to form metaphyses, and that terminate in epiphyses) the outermost portions of bone are composed on compact bone; the internal core is made of spongy bone long bone diaphysis and metaphysis are full of bone marrow the epiphyses use their spongy cores for more effective dispersion of force and pressure at the joints at the internal edge of the epiphysis is an epiphyseal growth plate - which is a cartilaginous structure and the site of longitudinal growth periosteum surrounds the long bond to protect it as well as serve as a site for muscle attachment - a healthy periosteum is necessary for bone growth and repair structures in the musculoskeletal system are held together with dense connective tissue; tendons attach muscle to bone and ligaments hold bones together at joints

Functions of the parasympathetic nervous system

conserves energy vagus nerve is responsible for much of the parasympathetic innervation of the thoracic and abdominal cavity

nutrients, waste, hormones (blood)

concentration gradients guide much of the movement of these substances to and from the tissues -carbohydrates and amino acids are absorbed into the capillaries of the small intestine and enter the systemic circulation via the hepatic portal system -fats are absorbed into lacteals in the small intestine, bypassing the hepatic portal circulation to enter systemic circulation via the thoracic duct (when released from intestinal cells, fats are packaged into lipoproteins, which are water soluble) -wastes enter the bloodstream by traveling down their conc gradients from the tissues to the capillaries- the blood eventually travels to the kidney where these waste products are filtered or secreted for elimination from the body -hormones enter the circulation in or near the organ where it is produced; occurs by exocytosis

Esophagus (digestive system)

connects the pharynx to the stomach; the top third is composed of skeletal muscle and the bottom third is composed of smooth muscle, and the middle third is a mix of both. the top is under somatic motor control (voluntary) and the bottom is under autonomic nervous control (involuntary) peristalsis proceeds down the digestive tract; certain exposure to chemicals, infectious agents, physical stimulation in the posterior pharynx and even cognitive stimulation can lead to the reversal of peristalsis (emesis = vomiting) swallowing is initiated in the muscles of the oropharynx (the upper esophageal sphincter) which pushes the bolus down to the stomach; then a muscular ring known as the lower esophageal sphincter (cardiac sphincter) relaxes and opens to allow the passage of food

Anatomy of the Excretory System

consists of the kidneys, ureters, bladder, and the urethra kidneys: -each kidney is subdivided into a cortex and a medulla; the cortex is the outermost layer, while the medulla of the kidney sits within the cortex -each kidney has a renal hilum, which is a deep slit in the center of its medial surface -the widest part of the ureter, the renal pelvis, spans almost the entire width of the renal hilum -the renal artery, renal vein, and ureter enter and exit through the renal hilum -the kidney has one of the few portal systems in the body - the renal artery branches out, passes through the medulla, and enters the cortex as afferent arterioles; the highly convoluted capillary tufts derived from these afferent arterioles are known as glomeruli; after blood passes through a glomerulus, the efferent arterioles then form a second capillary bed- these capillaries surround the loop of Henle and are known as vasa recta -Bowman's capsule is a cuplike structure around the glomerulus; it leads to a long tubule with many distinct areas: the proximal convoluted tubule, the descending and ascending limbs of Loop of Henle, distal convoluted tubule, and the collecting duct --> the kidney's ability to excrete waste is tied to the specific placement of these structures bladder structure: -has a muscular lining known as detrusor muscle (parasympathetic activity causes the detrusor muscle to contract) -in order to leave the body, urine must pass through two sphincters - the internal and external urethral sphincters - the internal urethral sphincter consists of smooth muscle, it is contracted in its normal state; under involuntary control - the external urethral sphincter consists of skeletal muscle and is under voluntary control - micturition reflex: when the bladder is full, stretch receptors causes parasympathetic neurons to fire, and the detrusor muscle contracts; this contraction also causes the internal sphincter to relax - the next step is up to the individual: to urinate or to maintain the tone of external sphincter to prevent urination -urination itself is facilitated by the contraction of the abdominal musculature, which increases pressure within the abdominal cavity, resulting in compression of the bladder and increased urine flow rate

Viruses

contain genetic material, a protein coat (capsid) and sometimes a lipid-containing envelope are obligate intracellular parasites individual virus particles are called virions viral genomes may be made of various nucleic acids: -they are composed of DNA or RNA and may be single or double stranded -single stranded RNA viruses may be positive sense (that can be translated directly by the host cell) or negative sense (which requires a complementary strand to be synthesized by RNA replicase before translation) -retroviruses contain a single stranded RNA genome, from which complementary DNA strand is made using reverse transcriptase. the DNA strand can then be integrated into the genome

reflex arc

control reflexive behavior; purpose it to protect the muscles two types: monosynaptic and polysynaptic monosynaptic: a single synapse between the sensory neuron that receives the stimulus and the motor neuron that responds to it (ex: knee-jerk reflex) polysynaptic: there is at least one interneuron between the sensory and motor neuron (ex: stepping on a nail; withdrawal reflex)

Baroreceptors and chemoreceptors

detect changes in blood pressure when BP is too low they can stimulate the sympathetic NS which causes vasoconstriction, increasing BP chemoreceptors can detect when the osmolarity of the blood is too high, which could indicate dehydration - this promotes the release of ADH to increase the reabsorption of water, increasing blood volume and pressure (aldosterone release is also stimulated to increase the reabsorption of sodium and then water)

contraction of the heart

each heartbeat is composed of two phases: systole and diastole during systole, ventricular contraction and closure of the AV valves occurs and blood is pumped out of the ventricles during diastole, the ventricles are relaxed, the semilunar valves are closed, and blood from the atria fills the ventricles contraction of the ventricles generates a higher pressure during systole, whereas their relaxation during diastole causes the pressure to decrease the elasticity of the walls of the large arteries allows the vessels to maintain sufficient pressure while the ventricular muscles are relaxed

Tissue

epithelial, connective, muscle, and nervous tissue epithelial tissues cover the body and line the cavities, as a means of protection against pathogen invasion and desiccation; cells are joined together in the basement membrane; in most organs epithelial tissue constitute the parenchyma, the functional parts of the organs; cells are polarized; classified according to # of layers and shape of cells connective tissues support the body and provide a framework for the epithelial cells to carry out their functions; main contributors to the stroma or support structure; bone, cartilage, tendons, ligaments are all ex; most cells in connective tissues produce and secrete materials such as collagen and elastin to form the extracellular matrix

the menstrual cycle

estrogen and progesterone levels rise and fall in a cyclic pattern follicular phase begins when the menstrual flow, which sheds the uterine lining of the previous cycle, begins -egg develops, endometrial lining becomes vascularized and glandularized - increase in FSH, LH doesn't change -estrogen decreases then increases -progesterone decreases ovulation -a surge of LH induces ovulation, the release of the ovum from the ovary into the abdominal (peritoneal) cavity -FSH increases, estrogen increases, progesterone decreases luteal phase -after ovulation, LH causes the ruptured follicle to form the corpus luteum, which secretes progesterone to maintain the endometrium -progesterone starts to rise, while estrogen levels remain high -high levels of progesterone cause negative feedback on GnRH, FSH, and LH, preventing the ovulation of multiple eggs menstruation -assuming that implantation doesn't occur, the corpus luteum loses its stimulation from LH, and progesterone levels decline, and the uterine lining is sloughed off -the loss of high levels of estrogen and progesterone removes the block on GnRH so that the next cycle can begin

Loop of Henle

filtrate from the PCT enters the descending limb of the Loop of Henle, which dives deep into the medulla before turning around to become the ascending loop of Henle the descending limb is permeable only to water, and the medulla has an ever-increasing osmolarity as the descending limb travels deeper into it --> as the descending limb traverses deeper into the medulla, the increasing interstitial concentration favors the outflow of water from the descending limb, which is reabsorbed into the vasa recta the kidney is capable of altering the osmolarity of the interstitium - this creates a gradient that, coupled with selective permeability of the nephron, allows maximal reabsorption and conservation of water together the vasa recta and the nephron create a countercurrent multiplier system - this means that the flow of filtrate through the loop of Henle is in the opposite direction from the flow of blood through the vasa recta --> the filtrate is constantly being exposed to hypertonic blood, which allows max reabsorption of water as the descending limb transitions to become the ascending limb, a change in permeability occurs: -the ascending limb is only permeable to salts and is impermeable to water; the ascending limb maximizes salt reabsorption and takes advantage of the decreasing medullary osmolarity at the transition from the inner to outer medulla, the loop of Henle becomes thicker in what is termed the diluting segment - only section of the nephron that can produce urine that is more dilute than the blood; this is important in periods of overhydration and provides a mechanism for eliminating excess water

Noncellular Nonspecific Defenses

first line of defense is the skin (integument) - provides a physical barrier between the outside world and our internal organsm, preventing most bacteria, viruses, fungi, and parasites from entering the body; antibacterial enzymes called defensins can be found on the skin; sweat also has antimicrobial properties the respiratory system also has mechanisms to prevent pathogens from entering the body: mucous membranes, lined with cilia to trap particulate matter and expel it mucous membranes around the eye and in the oral cavity produce a nonspecific bacterial enzyme called lysozyme, which is secreted in tears and saliva gastrointestinal tract: -the stomach secretes acid, resulting in the elimination of most pathogens -the gut is colonized by bacteria and most of this bacteria lack the necessary characteristics to cause an infection - many antibiotics reduce the population of gut flora, providing an opportunity for the growth of pathogens resistant to that antibiotic complement system consists of a number of proteins in the blood that act as a nonspecific defense against bacteria -complement can be activated through a classical pathway (which requires the binding of an antibody to a pathogen) or an alternative pathway (which does not require antibodies) - complement proteins punch holes in the cell walls of bacteria, making them osmotically unstable interferons are proteins that prevent viral replication and dispersion; they cause nearby cells to decrease production of both viral and cellular proteins; they also decrease the permeability of these cells, making it harder for a virus to infect them -upregulate MHC class I and class II molecules, resulting in increased antigen presentation and better detection of the infected cells by the immune system -responsible for many "flu-like" symptoms that occur during viral infection, including malaise, tiredness, muscle soreness, and fever

fundamental concepts of genetics

genes are DNA sequences that code for heritable traits that can be passed from one generation to the next taken together, all genes are organized into chromosomes to ensure that genetic material is passed easily to daughter cells during mitosis and meiosis each gene may have alternative forms called alleles the genetic combination possessed by an individual is known as a genotype, and the manifestation of a given genotype as an observable trait is a phenotype each human being possesses two copies of each chromosome, called homologues, except for male sex chromosomes (XY) each gene has a particular locus, or location on a specific chromosome; a normal locus of a particular gene is consistent among human beings - a gene can be described by its location if only one copy of an allele is needed to express a given phenotype, the allele is said to be dominant and is usually represented by a capital letter; if two copies are needed, the allele is said to be recessive and is usually represented with a lowercase letter if both alleles are the same for a given gene, the individual is said to have a homozygous genotype; if the alleles are different, the individual has a heterozygous genotype a hemizygous genotype describes a situation in which only one allele is presented for a given gene as in the case for parts of the X chromosome in males

cardiac muscle

has characteristics of both smooth muscle and skeletal muscle -primarily uninucleated, but cells may contain two nuclei - like smooth muscle, cardiac muscle contraction is involuntary and innervated by the autonomic nervous system - unlike smooth muscle, cardiac muscle appears striated like skeletal muscle -cardiac muscle cells are connected by intercalated discs that contain gap junctions (these are connections between the cytoplasm of adjacent cells, allowing for the flow of ions directly between cells) --> this allows for rapid and coordinated depolarization of muscle cells and efficient contraction of cardiac muscle - cardiac muscle cells can define and maintain their own rhythm, called myogenic activity --> starting at the SA node, depolarization spreads using conduction pathways to the AV node; then depolarization spreads to the bundle of His and its branches, then to the Purkinje fibers --> the gap junctions allow for progressive depolarizations to spread via ion flow across the gap junctions between cells - the Nervous and endocrine systems have a role in the regulation of cardiac muscle contraction

Hardy-Weinberg Principle

how often an allele appears in a population is known as its allele frequency evolution results from changes in these gene frequencies in reproducing populations over time however, when the gene frequencies of a population are not changing, the gene pool is stable and evolution is ostensible not occurring; the following five criteria are mandatory for this to be possible (states that if a population meets certain criteria, then the allele frequencies will remain constant) 1. the population is very large, no genetic drift 2. there are no mutations that affect the gene pool 3. mating between individuals in the population is random (no sexual selection) 4. there is no migration of individuals into or out of the population 5. the genes in the population are all equally successful at being reproduced - if all conditions are met, the population is said to be in Hardy-Weinberg equilibrium - an equation to predict the allelic and phenotypic frequencies: p is the frequency of the dominant allele T and q is the frequency of the recessive allele t; because there are only two choices at the same gene locus, p + q = 1 --> the combined allele frequencies of T and t must be equal to 100% ... if you square both sides of the equation you get: p^2 + 2pq + q^2 = 1 p^2 is the frequency of TT genotype, 2pq is the frequency of Tt, and q^2 is the frequency of tt the first question tells us about the frequency of alleles in the population, whereas the second provides info about the frequency of genotypes and phenotypes in population these equations can also be used to demonstrate that evolution is not occurring in a population

Gestation and Birth

human gestation lasts an estimated 280 days, divided into three trimesters 1st trimester: the major organs start to develop during the first few weeks; the heart begins to beat at approx 22 days, and soon after the eyes, gonads, lumbs, and liver start to form. by five weeks the embryo is 10mm long and by week six it is 15 mm long. by week seven the bones start to harden, and by week eight most of the organs have formed and the brain is fairly developed -- becomes the fetus! at the end of the third month the fetus is 9cm long. 2nd trimester: the fetus undergoes a lot of growth, it begin to move in the amniotic fluid and its face takes on a human appearance, and its toes and fingers elongate. By the end of the sixth month the fetus measures 30 to 36 cm long 3rd trimester: 7th and 8th months are characterized by continued rapid growth and further brain development. antibodies are transported from mother to fetus for protection and preparation for the outside world (this transfer is always there but is more rapid in the ninth month). birth: vaginal birth (parturition) is accomplished by rhythmic contractions and uterine smooth muscle, coordinated by prostaglandins and the peptide hormone oxytocin. -birth has 3 basic phases: first, the cervix thins out and the amniotic sac ruptures ("water breaking") and then strong contractions result in the birth of the fetus. -finally, the placenta and umbilical cord are expelled; this is afterbirth

Summation and Tetanus

if a muscle fiber is exposed to frequent and prolonged stimulation, it will have insufficient time to relax --> the contractions will combine, become stronger and more prolonged (frequency summation) if the contractions become so frequent that the muscle is unable to relax at all, this is known as tetanus --> prolonged tetanus will result in muscle fatigue note that tetanus (the disease) includes tetanus as one of its primary clinical features, but that tetanic physiology also occurs under normal circumstances with multiple simple twitches in succession

pregnancy

if fertilization occurs, zygote develops into a blastocyst that implants in the uterine lining and secretes human chorionic gonadotropin (hCG)

Viral Life Cycle

infection, translation and progeny assembly, progeny release infect cells by attaching to specific receptors and then can enter by fusing with the plasma membrane, being brought in by endocytosis, or injecting the genome into the cell the virus reproduces by replicating and translating genetic material using the host cell's ribosomes, tRNA, amino acids, and enzymes viral progeny are released through cell death, lysis, or extrusion

movable joints

include hinge joints, ball-and-socket joints, pivot joints, and gliding joints; they permit bones to shift relative to one another movable joints are strengthened by ligaments, which are pieces of fibrous tissue that connect bones to one another and consist of a synovial capsule, which encloses the actual joint cavity (articular cavity) a layer of soft tissue called the synovium secretes synovial fluid, which lubricates the movement of structures in the joint space the articular cartilage contributes to the joint by coating the articular surfaces of the bones so that impact is restricted to the lubricated joint cartilage, rather than to the bones when a muscle is attached to two bones, its contraction will cause one of the bones to move -the end of the muscle with a larger attachment to bone is called the origin; the end with the smaller attachment to bone is called the insertion often our muscles work in antagonistic pairs; one relaxes while the other contracts muscles can also be synergistic - working together to accomplish the same function muscles and the types of movement they coordinate: a flexor muscle decreases the angle across a joint; an extensor increases or straightens this angle; an abductor moves a part of the body away from the midline; an adductor moves a part of the body toward the midline; medial and lateral rotation describe motions that occur in limbs

breathing mechanism

inhalation is an active process; we use our diaphragm as well as the external intercostal muscles to expand the chest cavity - as the diaphragm flattens and the chest wall expands outward, the intrathoracic volume increases - because the intrapleural space most closely abuts the chest wall, its volume increases first - decrease in intrapleural pressure - gas in lungs is higher pressure than intrapleural space so the lungs expand into the space and the pressure in lungs will drop... air will be sucked in from a higher-pressure environment (the outside world) --> negative pressure breathing bc the driving force is the lower (relatively negative) pressure in the intrapleural space compared with the lungs ***diaphragm contracts during inhalation exhalation can be active or passive: -passive: relaxation of muscles of inspiration and elastic recoil of the lungs allow the chest cavity to decrease in volume, reversing the pressure differentials seen in inhalation -active: the internal intercostal muscles and abdominal muscles can be used to forcibly decrease the volume of chest cavity, pushing out air

cell specialization

initial stage - specification: the cell is reversibly designated as a specific cell type next - determination: the cell is irreversibly committed to a specific lineage (there are multiple pathways for determination to occur: during cleavage or by the secretion of specific molecules from nearby cells known as morphogens, which cause neighboring cells to follow a particular developmental pathway) differentiation: a process of changing structure, function, and the biochemistry of the cell to match the cell type -stem cells are cells not yet differentiated, or cells that give rise to other cells that will differentiate -the tissues a particular stem cell can differentiate into are determined by its potency (cells with the greatest potency are called totipotent - can differentiate into any cell type); pluripotent cells can differentiate into any cell type except of placental structures; multipotent cells can differentiate into multiple types of cells within a particular group

muscle contraction: initiation

initiation: -contraction starts at the neuromuscular junction, where the NS communicates with muscles via efferent neurons -this signal travels down the neuron until it reaches the nerve terminal, where acetylcholine is released into the synapse (in the case of the neuromuscular junction, the nerve terminal can also be called the motor end plate) -acetylcholine binds to receptors on the sarcolemma, causing depolarization - each nerve terminal controls a group of myocytes; together, the nerve terminal and its myocytes constitute a motor unit - depolarization leads to an action potential, which travels down the sarcolemma and to the T-tubules --> travels down the T-tubules and into the muscle tissues at the SR --> calcium ions are released at the SR --> the calcium ions bind to a regulatory subunit in troponin, triggering a change in the conformation of tropomyosin --> exposes the myosin-binding sites on the actin filament

Two types of digestion

intracellular digestion - as a part of metabolism, involves the oxidation of glucose and fatty acids for energy (extracted from our foods) the process by which these nutrients are obtained from the food occurs within the lumen of the alimentary canal (runs from the mouth to the anus and is sectioned off by sphincters) and is called extracellular digestion - this is technically "outside" of the body because the lumen of the gastrointestinal tract communicates directly with the outside world

jejunum and ileum (small intestine)

involved in absorption of nutrients; the small intestine is lined with villi which are small, fingerlike projections from the epithelial lining each villus has many microvilli, drastically increasing the surface area available for absorption; at the middle of each villus there is a capillary bed for the absorption of water-soluble nutrients and a lacteal (a lymphatic channel that takes up fats for transport into the lymphatic system) simple sugars and amino acids are absorbed by secondary active transport and facilitated diffusion into the epithelial cells lining the small intestine; then, these substances move across the epithelial cell membrane into the intestinal capillaries; blood is constantly passing by the epithelial cells, carrying carbs and amino acids away --> this creates a concentration gradient such that the blood always has a lower conc of monosaccharides and amino acids than inside the epithelial cells - simple carbs and amino acids diffuse from epithelial cells into the capillaries; the absorbed molecules then go to the liver via hepatic portal circulation short-chain fatty acids will follow the same process as carbohydrates and amino acids by diffusing directly into the intestinal capillaries - these fatty acids do not require transporters because they are already nonpolar so they can easily transverse the cellular membrane - larger fats, glycerol, and cholesterol move separately into the intestinal cells but then reform into triglycerides -the triglycerides and esterified cholesterol molecules are packaged into chylomicrons (rather than entering the bloodstream, the chylomicrons enter the lymphatic system through lacteals - small vessels that form the beginning of the lymphatic system --> these lacteals converge and enter the venous circulation at the thoracic duct which empties into the left subclavian vein) vitamins are also absorbed in the small intestine (fat soluble vitamins A, D, E, and K); fat-soluble vitamins dissolve directly into chylomicrons to enter the lymphatic circulation; the water-soluble vitamins are taken up along with water, amino acids, and carbs across the endothelial cells of the small intestine, passing directly into the plasma the small intestine also absorbs water - much of the fluid is reabsorbed through osmosis; as solutes are absorbed into the bloodstream, water is drawn from them, eventually reaching the capillaries (passes transcellularly across the cell membrane AND paracellularly squeezing between cells to reach the blood)

Large Intestine

involved in water absorption divided into three major sections: the cecum, the colon, and the rectum cecum is an outpocketing that accepts fluid exiting the small intestine through the ileocecal valve and is the site of attachment of the appendix (a small fingerlike projection that was once thought to be vestigial -- recent evidence suggests it might have a role in warding off certain bacterial infections and repopulating the large intestine with normal flora after episodes of diarrhea) the colon is divided into ascending, transverse, descending, and sigmoid colons --> its main function is to absorb water and salts from the undigested material left over from the small intestine; the colon concentrates the remaining material into feces (too little or too much water absorption can cause diarrhea or constipation) the rectum serves as storage for feces; the anus is the opening through which wastes are eliminated and consists of two sphincters (the internal and external sphincters) - the external sphincter is under voluntary (somatic) control and the internal sphincter is under involuntary (autonomic) control

humoral immunity

involves the production of antibodies, which may take as long as a week to become fully effective after the initial infection - these antibodies are specific to the antigens of the invading microbe; antigens are produced by B cells (activated in the spleen and lymph nodes) antibodies (immunoglobulins Ig) can carry out many different jobs in the body; when an antibody binds to an antigen, the response depends on the location for antibodies secreted into the body fluids, there are three main possibilities: 1. once bound to a specific antigen, antibodies may attract other leukocytes to phagocytize those antigens immediately (opsonization) 2. antibodies may cause pathogens to clump together (agglutinate) to form large insoluble complexes that can be phagocytized 3. antibodies can block the ability of a pathogen to invade tissues, essentially neutralizing it for cell-surface antibodies, the binding of antigen to B cell causes activation of that cell, resulting in its proliferation and formation of plasma and memory cells in contrast, when antigen binds to antibodies on the surface of mast cells, it causes degranulation (exocytosis of granule contents), releasing histamine, causing an inflammatory allergic reaction not all B cells that are generated will actively or constantly produce antibodies - antibody production is energetically expensive -naive B cells (those that have not been exposed to an antigen) wait in the lymph nodes for their particular antigen to come along -upon exposure to the correct antigen, a B cell will proliferate and produce two types of daughter cells -primary response: plasma cells produce large amounts of antibodies and memory B cells stay in the lymph node awaiting reexposure to the same antigen, which will lead to the secondary response

pharynx (digestive system)

leads from the mouth to the esophagus; also connects to the larynx (part of the respiratory tract) pharynx can be divided into three parts: 1. nasopharynx (behind the nasal cavity) 2. oropharynx (at the back of the mouth) 3. laryngopharynx (above the vocal cords) food is prevented from entering the larynx via the epiglottis

Bacteriophage

lytic cycle - produces massive numbers of new virions until the cell lyses; bacteria are virulent lysogenic cycle - the virus integrates into the host genome as a provirus or prophage, which can then reproduce along with the cell; the provirus can remain in the genome indefinitely, or may leave the genome in response to a stimulus and enter the lytic cycle

Cells of the innate immune system: macrophages

macrophages (type of agranulocyte) resides within tissues; these cells derive from blood-borne monocytes and can become a resident population within a tissue -when a bacterial invader enters a tissue, the macrophages become activated; the activated macrophage does three things: phagocytizes the the invader through endocytosis, digests the invader using enzymes, and presents little pieces of the invader to other cells using a protein called major histocompatibility complex (MHC) MHC binds to a pathogenic peptide (antigen) and carries it to the cell surface, where it can be recognized by the cells of the adaptive immune system in addition, macrophages release cytokines, a chemical substance that stimulates inflammation and recruit additional immune cells to the area

membrane bound organelles

membranes of eukaryotic cells consist of a phospholipid bilayer; its surfaces are hydrophilic and the inner portion is hydrophobic cytosol allows for the diffusion of molecules throughout the cell the nucleus: contains all the genetic info needed for replication of the cell; surrounded by a nuclear membrane that is a double membrane that maintains a nuclear environment separate and distinct from the cytoplasm; nuclear pores allow selective two way exchange; the DNA contains coding regions called genes, wound with histones and further wound into chromosomes. There is a subsection called the nucleolus where rRNA is synthesized (takes up 25% of the volume of the entire nucleus, considered the darker spot of the nucleus) mitochondria: has an inner and outer membrane; the outer membrane serves as a barrier between the cytosol and the inner environment of the mitochondrion; the inner membrane, which is arranged into cristae, contains the molecules and enzymes of the ETC; the space between the two membranes is called the intermembrane space; the space inside the inner membrane is called the mitochondrial matrix. Mitochondria are different in that they are semiautonomous - they contain some of their own genes and replicate independently of the nucleus via binary fission (they are paradigmatic examples of cytoplasmic or extranuclear inheritance - the transmission of genetic material independent of the nucleus). the mitochondria is also capable of killing the cell by release of enzymes from the ETC - apoptosis. lysosomes: contains hydrolytic enzymes that are capable of breaking down many different substrates; often function in conjunction with endosomes which transport, package, and sort cell material travelling to and from the membrane; autolysis when lysosomes release their hydrolytic enzymes leads to the degradation of cellular components endoplasmic reticulum: series of interconnected membranes that are actually contiguous with nuclear envelope; there's the smooth ER and rough ER; rough ER is studded with ribosomes, which permit the translation of proteins destined for secretion directly into its lumen; the smooth ER lacks ribosomes and is utilized primarily for lipid synthesis and the detoxification of certain drugs and poisons; the SER also transports proteins from the RER to the golgi apparatus golgi apparatus: consists of stacked membrane bound sacs; materials from the ER are transferred to the golgi in vesicles; inside the golgi these cellular products may be modified by the addition of groups like carbs, phosphates, sulfates; may also modify cellular products through intro of signal sequences, which direct the delivery of the product to a specific location. released via exocytosis peroxisomes contain hydrogen peroxide; one of the primary functions is the breakdown of very long chain fatty acids via beta oxidation; they participate in the synthesis of phospholipids and contain some of the enzymes involved in PPP.

Cells of the innate immune system: granulocytes

neutrophils are the most populous leukocyte in blood and are very short-lived (a little more than five days); these cells are phagocytic and target bacteria; they can follow bacteria using chemotaxis (the movement of an organism according to chemical stimuli); they detect bacteria once they have been opsonized (marked with an antibody from the B cell); dead neutrophil collections are responsible for the formation of pus eosinophils contain bright red-orange granules and are primarily involved in allergic reactions and invasive parasitic infections; upon activation, these cells release large amount of histamine, an inflammatory mediator - this results in vasodilation and increased leakiness of the blood vessels, allowing additional immune cells (esp macrophages and neutrophils) to move out of the blood stream and into tissue; inflammation is useful against extracellular pathogens basophils contain large purple granules and are involved in allergic responses; they are the least populous of leukocytes; mast cells are closely related to basophils; both basophils and mast cells release large amounts of histamine in response to allergens, leading to an inflammatory response

WBCs: Granulocytes

neutrophils, eosinophils, basophils named because they contain cytoplasmic granules that are visible by microscopy; these granules contain a variety of compounds that are toxic to invading microbes; these compounds can be released through exocytosis involved in inflammatory responses, allergies, pus formation, and destruction of bacteria and parasites

Aerobes and Anaerobes

obligate aerobes are bacteria that require oxygen for metabolism anaerobes are bacteria that use fermentation or some other cellular metabolism that does not require oxygen obligate anaerobes cannot survive in an oxygen-containing environment facultative anaerobes toggle between metabolic processes using oxygen and switching to anaerobic processes aerotolerant anaerobes are unable to use oxygen for metabolism but are unharmed in its presence

meiosis

occurs in gametophytes and results in up to four nonidentical sex cells (gametes); meiosis has one round of replication and two rounds of division meiosis I results in homologous chromosomes being separated, generating haploid daughter cells (Reductional division) -prophase I: the same events occur as in prophase of mitosis, except that homologues come together and intertwine in a process called synapsis. The four chromatids are referred to as a tetrad, and crossing over exchanges genetic material between one chromatid and material from a chromatid in the homologous chromosome. -metaphase I: homologous pairs align at the metaphase plate; they are lined up across from each other at the metaphase plate and are held by one spindle fiber -anaphase I: homologous pairs separate and are pulled to opposite poles of the cell (disjunction) -telophase I: a new nuclear membrane forms around each nucleus; the chromosomes may or may not fully decondense, and the cell may enter interkinesis (partially uncoil) after cytokinesis meiosis II results in the separation of sister chromatids, without a change in ploidy and therefore known as equatorial division -prophase II: the nuclear envelope dissolves, nucleoli disappear, the centrioles migrate to opposite poles, and the spindle apparatus forms -metaphase II: the chromosomes align along the plate -anaphase II: the centromeres divide, separating the chromosomes into sister chromatids; these chromatids are pulled to opposite poles by spindle fibers -telophase II: a nuclear membrane forms around each nucleus, cytokinesis occurs; the end result is up to four haploid daughter cells produced per gametocyte

Fertilization

occurs in the widest part of the fallopian tube called the ampulla after penetration of the sperm through the cell membrane, the cortical reaction, a release of calcium ions causes depolarization to prevent fertilization by multiple sperm cells and the increased calcium conc increases the metabolic rate of the newly formed diploid zygote dizygotic (fraternal) twins: form from fertilization of two different eggs released during one ovulatory cycle by two different sperm; are no more genetically similar than any other pair of siblings monozygotic (identical) twins form when a single zygote splits into two; if division is incomplete, conjoined twins may result

bone remodeling

osteoblasts build the bone and osteoclasts resorb it (chew bone) these processes together contribute to the constant turnover of bone during bone formation, essential ingredients such as calcium and phosphate are obtained from the blood during bone resorption, these ions are released back into the bloodstream bone remodeling occurs in response to stress, and bone actually remodels in such a way as to accommodate the repetitive stresses faced by the body endocrine hormones may also affect bone metabolism parathyroid hormone, a peptide hormone released by parathyroid glands in response to low calcium in blood, promotes resorption of bone; releases calcium into the bloodstream calcitonin responds to high blood calcium and promotes bone formation, lowering blood calcium levels

pathway of sperm

pathway of sperm: SEVE(N) UP the testes have two functional components: the seminiferous tubules (sperm production, they are nourished by Sertoli cells) and interstitial cells of Leydig (secrete testosterone and other male sex hormones - androgens) as sperm are formed they pass the epididymis where their flagella gain motility and they are stored until ejaculation during ejaculation, the sperm travel through the vas deferens and enter the ejaculatory duct at the posterior edge of the prostate gland; then the ducts fuse to form the urethra, which carries the sperm through the penis as they exit the body the seminal vesicles contribute fructose to nourish sperm; both the seminal vesicles and the prostate gland give the fluid milky alkaline properties so the sperm can survive in the relative acidity of the female reproductive tract the bulbourethral (Cowper's) glands produce a clear viscous fluid that cleans out any remnants of urine and lubricants the urethra during sexual arousal the combination of sperm and seminal fluid is semen

Nucleotide-level mutations

point mutations occur when one nucleotide in DNA is swapped for another: silent mutations occur when the change in nucleotide has no effect on the final protein synthesized from the gene; this most commonly occurs when the changed nucleotide is transcribed to be the third nucleotide in a codon because their is degeneracy (wobble) in the genetic code missense mutations occur when the change in nucleotide results in substituting one amino acid for another in the final protein nonsense mutations occur when the change in nucleotide results in substituting a stop codon for an amino acid in the final protein ------ frameshift mutations occur when nucleotides are inserted into or deleted from the genome; because mRNA transcribed from DNA is always read in 3-letter sequences called codons, insertion or deletion of nucleotides can shift the reading frame, usually resulting in either changes in the amino acid sequence or premature truncation of the protein (insertion or deletion mutations)

hematopoietic stem cells

precursor to granulocytes and agranulocytes also the cell type to give rise to RBCs and platelets

function of respiratory system: gas exchange

primary function of lungs the driving force of gas exchange is the pressure differential of the gases each alveolus is surrounded by a network of capillaries and these capillaries facilitate gas exchange gas exchange through simple diffusion across conc gradients -deoxygenated blood with high CO2 conc is brought to the lungs by pulmonary arteries -oxygenated blood with a low CO2 conc leaves the lungs by pulmonary veins O2 in the alveoli flows down its partial pressure gradient from the alveoli into the pulmonary capillaries, where it can bind to Hb for transport. CO2 flows down its partial pressure gradient from the capillaries into the alveoli for expiration

prions and viroids

prions are infectious proteins that trigger the misfolding of other proteins, usually convering an alpha helical structure to a beta pleated sheet - this decreases the solubility of the protein and increases resistance to degradation viroids are plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes and, potentially cell death

Implantation

process in which a blastocyst attaches itself to the wall of the uterus (blastula stage) the placenta is connected to the embryo via umbilical cord, the two arteries carry deoxygenated blood and waste to the placenta for exchange; the vein carries freshly oxygenated blood rich with nutrients from the placenta to the embryo (until the placenta is fully functional, the embryo is supported by a yolk sac, which is also the site of early blood cell development) - the yolk sac has two extraembryonic membranes - 1. the allantois is involved in early fluid exchange between the embryo and the yolk sac -2. amnion, a thin, tough membrane filled with amniotic fluid; serves as a shock absorber, lessening the impact of maternal motion

Oogenesis

production of female gametes undergo same meiotic process as male gametes do there is no unending supply of stem cells analogous to spermatogonia in females; all of the oogonia a woman will ever have are formed during fetal development by birth, all of the oogonia have already undergone DNA replication and are considered primary oocytes (2n). once a woman reaches menarche (her first menstrual cycle), one primary oocyte per month will complete meiosis I, producing a secondary oocyte and a polar body. the secondary oocyte does not complete meiosis unless fertilization occurs. oocytes are surrounded by two layers: zone pellucida (protects and supplies compounds necessary for sperm binding) and the corona radiata (layer of cells adhered to the oocyte during ovulation) upon the completion of meiosis II, the haploid pronuclei of the sperm and the ovum join and create a diploid zygote.

Cytoskeleton

provide structure and helps maintain shape; a conduit for the transport of materials around the cell three components of the cytoskeleton: microfilaments, microtubules, and the intermediate filaments microfilaments: actin; resistant to both compression and fracture, providing protection for the cell; actin filaments use ATP to generate force for movement by interacting with myosin (like in muscle contractions) -play a role in cytokinesis (division between daughter cells) -during mitosis the cleavage furrow is formed from microfilaments, which organize as a ring at the side of division between two new daughter cells microtubules: hollow polymers of tubulin proteins; provides primary pathways along which motor proteins like kinesin and dynein carry vesicles; cilia and flagella are composed of microtubules -cilia are projections involved in the movement of materials along the surface of the cell -flagella are involved in movement of the cell itself -cilia and flagella are in a 9+2 structure -centrioles are found in the centrosome, organizing centers for microtubules intermediate filaments: diverse group including keratin, desmin, vimentin, and lamins; involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton; able to withstand a lot of tension, increasing rigidity; helps anchor other organelles;

Erythrocytes

red blood cells; designed for oxygen transport each erythrocyte contains about 250 million molecules of Hb, each of which can bind four molecules of oxygen; each red blood cell can carry approximately 1 billion molecules of oxygen RBCs are biconcave, or indented on both sides- serves a dual purpose: shape assists them in travelling in tiny capillaries, and it increases the cell's surface area, increasing gas exchange when RBCs mature, the nuclei, mitochondria, and other membrane-bound organelles are lost --> makes space for the molecules of Hb they rely entirely on glycolysis for ATP RBCs are unable to divide since they lack nuclei can live for 120 days in the bloodstream before the cells in the liver and spleen phagocytize senescent (old) RBCs to recycle them for their parts

Genetic Drift

refers to changes in the composition of the gene pool due to chance; genetic drifts tend to be more pronounced in small populations the founder effect is a more extreme case of genetic drift in which a small population of a species finds itself in reproductive isolation from other populations as a result of natural barriers, catastrophic events, or other bottlenecks that drastically and suddenly reduce the size of the population available for breeding because the breeding group is small, inbreeding, or mating between two genetically related individuals, may occur in later generations - inbreeding encourages homozygosity, which increases the prevalence of both homozygous dominant and recessive genotypes these effects cause a reduction in genetic diversity, which is often the reason why a small population may have increased prevalence of certain traits or diseases this loss of genetic variation may cause reduced fitness of the population, a condition known as inbreeding depression on the opposite end of the spectrum, outbreeding or outcrossing is the introduction of unrelated individuals into a breeding group -- theoretically, this could result in increased variation within a gene pool and increased fitness of the population

excretory system

regulates blood pressure, blood osmolarity, acid base balance, and the removal of nitrogenous wastes the kidneys play an essential role in these functions

Functions of the excretory system

regulation of blood pressure, blood osmolarity, acid-base balance, and removal of nitrogenous wastes regulation of blood pressure: - aldosterone is a steroid hormone that is secreted by the adrenal cortex in response to decreased blood pressure; decreased BP stimulates the release of renin from juxtaglomerular cells in the kidney --> renin then cleaves angiotensinogen, a liver protein, to form angiotensin I - this peptide is then metabolized to angiotensin-converting enzyme in the lungs to form angiotensin II, which promotes the release of aldosterone from the adrenal cortex -aldosterone works by altering the ability of the DCT and collecting duct to reabsorb sodium (water will flow with it) - increases blood volume, increasing BP -ADH is a peptide hormone synthesized in the hypothalamus and released by the posterior pituitary in response to high blood osmolarity - it directly alters the permeability of the collecting duct, allowing more water to be reabsorbed by making the cell junctions of the duct leaky --> increased concentrations in the interstitium will then cause the reabsorption of water from the tubule (alcohol and caffeine both inhibit ADH release and lead to frequent excretion of dilute urine) *the cardiovascular system also regulates BP osmoregulation: the osmolarity of the blood must be tightly controlled to ensure correct oncotic pressures within the vasculature; the kidneys control osmolarity by modulating the reabsorption of water and by filtering and secreting dissolved particles; when blood osmolarity is low, excess water will be excreted, while solutes will be reabsorbed in higher concentrations; when blood osmolarity is high, water reabsorption increases and solute excretion increases acid-base balance: -the bicarbonate buffer system is the major regulator of blood pH

CO2 exchange in blood

removing CO2 is important CO2 can be carried by hemoglobin but Hb has a much lower affinity for CO2 than for O2 ... the vast majority of CO2 exists in the blood as HcO3- bicarbonate ion when CO2 enters a RBC, it encounters the enzyme carbonic anhydrase, which catalyzes the combination reaction between CO2 and water to form H2CO3 --> will dissociate into a proton an HCo3- which both have high solubilities in water, making this a more effective way of transporting metabolic wastes to the lungs for excretion

gross structure of myocytes

sarcomeres are attached end to end to form myofibrils (these are surrounded by a covering called sarcoplasmic reticulum SR, a modified endoplasmic reticulum that contains high conc of calcium ions) the sarcoplasm is a modified cytoplasm located just outside the SR the cell membrane of a myocyte is known as the sarcolemma - capable of propagating an action potential and can distribute the action potential to all sarcomeres in a muscle using a system of T-tubules that are oriented perpendicularly to myofibrils each myocyte (muscle cell) contains many myofibrils arranged in parallel and can also be called a muscle fiber the nuclei (there are many) are usually found at the periphery of each cell many myocytes in parallel form a muscle

skeletal muscle

skeletal muscle is responsible for voluntary movements; innervated by the somatic nervous system -due to the arrangement of actin and myosin into repeating units called sarcomeres, it appears striped or striated when viewed microscopically - skeletal muscle is multinucleated because it is formed as individual muscle cells fuse into long rods during development -there are multiple different types of fibers within skeletal muscle: red fibers (slow twitch fibers, have high myoglobin content and primarily derive their energy aerobically; also contain mitochondria to carry out oxidative phosphorylation), white fibers (fast twitch fibers; contain much less myoglobin) -muscles that contract slowly, but that can sustain activity (such as the muscles that support posture), contain a predominance of red fibers - muscles that contract rapidly, but fatigue quickly, contain mostly white fibers

parathyroid glands

small pea-like organs that regulate calcium and phosphate balance in blood, bones, and other tissues -the hormone produced by the parathyroid gland is named parathyroid hormone (PTH) - serves antagonistic hormone to calcitonin, raising blood calcium levels -PTH decreases excretion of calcium by the kidneys, increases absorption of calcium in the gut, and increases bone resorption (freeing up calcium) -as plasma calcium rises, PTH secretion is decreased -PTH also promotes phosphorus homeostasis by increasing the resorption of phosphate from bone and reducing reabsorption of phosphate in the kidney (thus promoting its excretion in urine) -PTH also activates vitamin D (which is required for the absorption of calcium and phosphate in the gut) overall effect of PTH is significant increase in blood calcium levels with little effect on phosphate (the absorption of phosphate in the gut and its excretion in the kidney somewhat cancel each other)

smooth muscle

smooth muscle is responsible for involuntary action; smooth muscle is controlled by the autonomic nervous system; it is found in the respiratory tree, digestive tract, uterus, blood vessel walls, etc; smooth muscle cells have a single nucleus; they contain actin and myosin but not as well-organized as skeletal muscle; compared to skeletal muscle, smooth muscle is more capable of sustaining contractions a constant state of low-level contraction (as may be seen in blood vessels) is called tonus smooth muscle can actually contract without nervous system input (myogenic activity) - they respond directly to other stimuli

Cartilage

softer and more flexible than bone; consists of a firm but elastic matrix called chondrin that is secreted by cells called chondrocytes fetal skeletons are made of mostly cartilage - this is advantageous because fetuses must grow and develop in a confined environment and then must transverse the birth canal adults have cartilage only in body parts that need a little extra flexibility or cushionin g cartilage also differs from bone in that is is avascular (without blood or the lymphatic vessels) and is not innervated most of the bones of the body are created by the hardening of cartilage into bone --> endochondral ossification and is responsible for the formation of most of the long bones of the body - bones may also be formed through intramembranous ossification, in which undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into, and replaced by, bone --> this occurs in bones of the skull

neurons

soma - cell body dendrites receive incoming messages from other cells and it is transmitted through the cell body before it reaches the axon hillock, which integrates the incoming signals (plays an important role in action potentials - the transmission of electrical impulses down the axon) the axon is a long appendage that terminates in close proximity to a target structure; most mammalian nerve fibers are insulated by myelin sheath (increasing the speed of transduction in the axon) -myelin is produced by oligodendrocytes in the CNS and schwann cells in the PNS -nodes of Ranvier are gaps that have no myelin sheath at the end of the axon is the nerve terminal/synaptic button (knob) - release of neurotransmitters small space between neurons is the synaptic cleft --> synapse

Consequences of mutations

some mutations can be advantageous, conferring a positive selective advantage that may allow the organism to produce fitter offspring some mutations can be deleterious one important class of deleterious mutations is known as inborn errors of metabolism - these are defects in genes required for metabolism; children born with these defects often require very early intervention in order to prevent permanent damage from the buildup of metabolites in various pathways

Spermatogenesis

spermatogonium --> primary spermatocyte --> secondary spermatocyte --> spermatid --> spermatozoan

Bacteria by shape

spherical - cocci rod-shaped - bacilli spiral-shaped - spirilli

skin structure

starting from the deepest layer and working outward, these layers are the hypodermis (subcutaneous layer), dermis, and epidermis; the skin is derived from the ectoderm the epidermis is also subdivided into layers called the strata; from the deepest layer outward: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum (Come, Let's Get Sun Burned) -the stratum basale contains stem cells and is responsible for the proliferation of keratinocytes, the predominant cells of the skin that produce keratin - the stratum spinosum - the cells of this layer are connected to each other and it is the site of Langerhan cells -in the stratum granulosum, the keratinocytes die and lose their nuclei - the stratum lucidum is only present in thick, hairless skin, such as the skin on the sole of your foot or palms, and is nearly transparents - the stratum corneum contains up to several dozen layers of flattened keratinocytes, forming a barrier that prevents invasion by pathogens and that helps to prevent loss of fluids and salts -hair projects above the skin and there are openings for sweat and sebaceous glands the dermis -consists of multiple layers: the upper layer is the papillary layer, which consists of loose connective tissue; then the denser reticular layer -sweat glands, blood vessels, and hair follicles originate in the dermis -most sensory receptors are located in the dermis -Ex: Merkel Cells (discs) are sensory receptors present at the epidermal-dermal junction; these cells are responsible for deep pressure and texture sensations - free nerve endings that respond to pain, Meissner's corpuscles respond to light touch, Ruffini endings respond to stretch; and Pacinian corpuscles respond to deep pressure and vibration the hypodermis: a layer of connective tissue that connects the skin to the rest of the body; this layer contains fat and fibrous tissue

Gallbladder (accessory organ)

stores, concentrates, and releases bile -upon release of CCK, the gallbladder contracts and pushes bile out into the biliary tree - the bile duct system merges with the pancreatic duct before emptying into the duodenum - common site of cholesterol or bilirubin stone formation - this is a painful condition that causes inflammation of the gallbladder

Gonads

testes secrete testosterone in response to LH and FSH; promotes sexual differentiation in male during gestation and promotes the development and maintenance of secondary sex characteristics ovaries secrete estrogen and progesterone in response to LH and FSH; estrogen is involved in the development of the female reproductive system during gestation and also promotes the development and maintenance of secondary sex characteristics; the two hormones govern the menstrual cycle and pregnancy

action potential

the all-or-none electrical signal that travels down a neuron's axon resting membrane potential is the net electric potential that exists across the cell membrane, created by movement of charged molecules across that membrane; for neurons the resting membrane potential is about -70mV with the inside of the neuron being negative relative to the outside --> the two most important ions involved in generating and maintaining the resting potential are K+ and Na+ Na+/K+ ATPase continually pumps sodium out of the cell and potassium into the cell to maintain their respective gradients (3 sodiums move out, and 2 potassiums move in) the axon hillock: -excitatory input causes depolarization (raising the membrane potential from its resting potential) and it makes the neuron more likely to fire an action potential --if the threshold is met, an action potential will be triggered -inhibitory input causes hyperpolarization (lowering the membrane potential from resting) and makes it less likely to fire an action potential - additive effect of multiple signals is summation if brought to the threshold, voltage-gated channels open in the membrane --> strong electrochemical gradient that promotes the migration of sodium into the cell and the inside of the cell becomes more positive, causing depolarization - then the sodium channels are inactivated and brought back near resting potential to be deinactivated; --> as K+ is driven out of the cell, there will be a restoration of the negative membrane potential, hyperpolarizing the neuron - this causes the neuron refractory to further action potential

Sarcomere

the basic contractile unit of skeletal muscle; made of thick and thin filaments the thick filaments are organized bundles of myosin, whereas thin filaments are made of actin along with two other proteins: troponin and tropomyosin --> these proteins help to regulate the interaction between actin and myosin filaments another protein, titin acts as a spring and anchors the actin and myosin filaments together, preventing excessive stretching of the muscle each sarcomere is divided into different lines, zones, and bands - Z lines define the boundaries of each sarcomere - M line runs down the center of each sarcomere, through the middle of the myosin filaments - the I band is the region containing exclusively thin filaments - the H zone contains only thick filaments - the A band contains thick filaments in their entirety, including any overlap with thin filaments

Anatomy of the immune system

the bone marrow produces all of the leukocytes (WBCs) that participate in the immune system through the process of hematopoiesis (two classes of leukocytes: granulocytes and agranulocytes) the spleen is a location of blood storage and activation of B cells, which turn into plasma cells to produce antibodies as a part of adaptive immunity when B cells leave the bone marrow, they are considered mature but naive because they have not yet been exposed to an antigen because these antibodies dissolve and act in blood, rather than within cells, this division of adaptive immunity is called humoral immunity T cells (another class of adaptive immune cells) mature in the thymus; they are agents of cell-mediated immunity because they coordinate the immune system and directly kill virally infected cells lymph nodes are a major component of the lymphatic system; they provide a place for immune cells to communicate and mount an attack; B cells can be activated here too other immune tissue is found in close proximity to the digestive system, which is a site of potential invasion by pathogen --> commonly called gut-associated lymphoid tissue (GALT) and include the tonsils and adenoids in the head -Peyer's patches in the small intestine and lymphoid aggregates in the appendix

endocrine system: hypothalamus

the bridge between the NS and endocrine system -by regulating the pituitary gland through tropic hormones, the hypothalamus is capable of having organism-wide effects; the hypothalamus is located in the forebrain, directly above the pituitary gland and below the thalamus -since it is really close to the pituitary, the hypothalamus controls the pituitary through paracrine release of hormones in a portal system that directly connects the two organs -the hypothalamus receives inputs from a variety of sources (ex: the part of the hypothalamus called the suprachiasmatic nucleus receives some of the light input from the retinae and helps control sleep-wake cycles) -the release of hormones by the hypothalamus is regulated by negative feedback -interacts with the posterior and anterior pituitary

cell to cell communication

the cell that is induced is called a responder (responsive cell) and to be induced, a responder must be competent, or able to respond to the inducing signals cell-cell communication can occur via: -autocrine signals act on the same cell that secreted the signal in the first place -paracrine signals act on cells in the local area -juxtacrine signals do not usually involve diffusion, but involve a cell directly stimulating receptors of an adjacent cell -endocrine signals involve secreted hormones that travel through the bloodstream to a distant target tissue if two tissues both induce further differentiation in each other, this is reciprocal induction signalling occurs via gradients

Prokaryotic cell structure

the cell wall and cell membrane of bacteria form the envelope. Together they control the movement of solutes into and out of the cell. gram positive cell walls have peptidoglycan; protection from a host's immune system; also has lipoteichoic acid gram negative cell walls also have peptidoglycan but in smaller amounts; has outer membranes containing phospholipids and lipopolysaccharides (triggers an immune response in humans - this inflammatory response is much stronger than the response to lipoteichoic acid)

electrical conduction of the heart

the coordinated, rhythmic contraction of cardiac muscle originates in an electrical impulse generated by and traveling through a pathway formed by four electrically excitable structures this pathway consists of the Sinoatrial (SA) node, the atrioventricular (AV) node, the bundle of His (AV bundle) and its branches, and the Purkinje fibers impulse initiation occurs in the SA node, which generates 60-100 signals per minute without requiring any neurological input; as the depolarization wave spreads from SA node, it causes the two atria to contract simultaneously -atrial systole (contraction) results in an increase in atrial pressure that forces a little more blood into the ventricles; this additional volume of blood is called the atrial kick and accounts for 5-30% of cardiac output next, the signal reaches the AV node, which sits at the junction of the atria and ventricles; the signal is delayed here to allow ventricles to fill completely before they contract the signal then travels down the bundle of His and its branches, embedded in the interventricular septum (wall), and to the Purkinje fibers, which distribute the electrical signal through the ventricular muscle the muscle cells are connected by intercalated discs, which contain many gap junctions directly connecting the cytoplasm of adjacent cells- this allows for coordinated ventricular contraction

proximal convoluted tubule (PCT)

the filtrate first enters the PCT; and in this region, amino acids, glucose, water-soluble vitamins, and the majority of salts are reabsorbed along with water; solutes that enter the interstitium (the connective tissue surrounding the nephron) are picked up by the vasa recta to be returned to the bloodstream for reuse within the body the PCT is also the site of secretion for a number of waste products, including Hydrogen ions, potassium ions, ammonia, and urea Major waste products excreted in the urine: DUMP the HUNK (H+, urea, NH3, K+)

collecting duct

the final concentration of urine will depend largely on the permeability of the collecting duct, which is responsive to both aldosterone and ADH as permeability of the collecting duct increases, so to does water reabsorption, resulting in further concentration of urine anything that is not reabsorbed from the tubule by the end of the collecting duct will be excreted; the point of no return

muscle contraction: shortening of the sarcomere

the free globular heads of the myosin molecules move toward and bind with the exposed sites on actin --> the newly formed actin-myosin cross bridges then allow myosin to pull on actin, which draws the thin filaments toward the M-line, resulting in shortening of the sarcomere myosin carrying hydrolyzed ATP is able to bind with the myosin binding site --> the release of inorganic phosphate and ADP in rapid succession provides the energy for the powerstroke and results in sliding of the actin filament over the myosin filament --> ATP binds to the myosin head, releasing it from actin --> this ATP is hydrolyzed to ADP and Pi, which recocks the myosin head sot that it is in the position to start another cross bridge cycle the repetitive binding and releasing of myosin heads on actin filaments allows the thin filament to slide along the thick filament, causing sequential shortening of the sarcomere --> sliding filament model

female reproductive system

the gonads are the ovaries, which produce estrogen and progesterone; they are located in the pelvic cavity and each contain thousands of follicles, which are multilayered sacs that contain, nourish, and protect immature ova (eggs) between puberty and menopause, one egg per month is ovulated into the peritoneal sac and drawn into the fallopian tube (oviduct), which is connected to the uterus, the site of fetal development.

Osmoregulation

the kidneys filter blood to form urine; the composition and the quantity of urine is determined by the present state of the body (ex: if blood volume is low and blood osmolarity is high, then it is most beneficial to the body to maximally retain water --> this results in low volume, highly concentrated urine) filtration: - in the kidneys, approximately 20% of the blood that passes through the glomerulus is filtered as fluid into the Bowman's space - the collected fluid is known as filtrate - the movement of fluid into Bowman's space is governed by Starling forces, which account for the pressure differentials in both hydrostatic and oncotic pressures between the blood and Bowman's space -the hydrostatic pressure in the glomerulus is significantly higher than that in Bowman's space, which causes fluid to move into the nephron -the osmolarity of blood is higher than that of Bowman's space, resulting in pressure opposing the movement of fluid into the nephron - but the hydrostatic pressure is much larger than the oncotic pressure so the net flow is still from blood into nephron secretion: - the nephrons are able to secrete salts, bases, acids, and urea directly into the tubule by either active or passive transport; the quantity and identity of the substances secreted into the nephron are directly related to the needs of the body at the time - the liver converts ammonia to urea, which travels to the kidney and is secreted into the nephron for excretion in urine - the kidneys are able to eliminate ions or other substances when present in relative excess in the blood - secretion is also a mechanism for excreting wastes that are too large to pass through glomerular pores reabsorption: -some compounds that are filtered or secreted may be taken back up for use -certain substances are almost always reabsorbed (vitamins, glucose, amino acids) - ADH and aldosterone can alter the quantity of water reabsorbed within the kidney in order to maintain blood pressure

function of respiratory system: thermoregulation

the large SA of interaction bt the alveoli and capillaries allows the respiratory system to assist in thermoregulation through vasodilation and vasoconstriction of capillary beds as capillaries expand, more blood can pass through these vessels and a larger amount of thermal energy can be dissipated... as capillaries contract, less blood can pass through, conserving thermal energy the respiratory system also transfers heat to the environment through evaporation of water in mucous secretions (panting in dogs and other animals)

other cells of the epidermis

the main cells are keratinocytes; keratin is resistant to damage and provides protection against injury, water, and pathogens; calluses form from excessive keratin deposition in areas of repeated strain due to friction; they provide protection to avoid damage in the future melanocytes are a cell type derived from neural crest cells and found in the stratum basale - these cells produce melanin, a pigment that serves to protect the skin from DNA damage caused by UV radiation; more melanocytes result in darker skin tone Langerhans cells are actually special macrophages that reside within the stratum spinosum - these cells are capable of presenting antigens to T-cells in order to activate the immune system

duodenum (digestive system)

the small intestine has three segments: the duodenum, the jejunum, and the ileum; the small intestine is up to 7 meters long -the duodenum is responsible for the majority of chemical digestion and has some minor involvement in absorption; most of the absorption takes place in the jejunum and the ileum DUODENUM -food leaves the stomach through the pyloric sphincter and enters the duodenum; the presence of chyme in the duodenum causes the release of brush-border enzymes like disaccharidases and peptidases -brush-border enzymes are present on the luminal surface of cells lining the duodenum and break down dimers and trimers of biomolecules into absorbable monomers - the duodenum also releases enteropeptidase which is involved in the activation of other digestive enzymes from the accessory organs of digestion -it also secretes hormones like secretin and CCK into the bloodstream The disaccharidases digest disaccharides - maltase, isomaltase, lactase, sucrase. The inability to break down the corresponding disaccharide can lead to bacteria in the intestines to hydrolyze that disaccharide, producing methane gas --> undigested disaccharides have an osmotic effect, pulling water into the stool and causing diarrhea (lactose intolerant people!) peptidases break down proteins; aminopeptidase is a peptidase secreted by glands in the duodenum that removes the N terminal amino acid from a peptide; dipeptidases cleave the peptide bonds of dipeptides to release free amino acids enteropeptidase is an enzyme critical for the activation of trypsinogen to produce trypsin - which initiates an activation cascade secretin is a peptide hormone that causes pancreatic enzymes to be released into the duodenum - it also regulates the pH of the digestive tract by reducing HCl secretion from the parietal cells and increasing bicarbonate secretion from the pancreas; secretin is also an enterogastrone, a hormone that slows motility through the digestive tract- slowing of motility allows increased time for digestive enzymes to act on chyme (especially fats) Cholecystokinin (CCK) is secreted in response to the entry of chyme into the duodenum - this peptide hormone secretes the release of bile and pancreatic juices and also acts in the brain where it promotes satiety bile is a complex fluid composed of bile salts, pigments, and cholesterol. bile salts are derived from cholesterol - serve an important role in mechanical digestion of fats and facilitate the chemical digestion of lipids -bile salts have a hydrophilic and hydrophobic region which allows them to be a bridge between aq and lipid environments - bile salts emulsify fats and cholesterol into micelles - a major pigment of bile is bilirubin which is a byproduct of the breakdown of hemoglobin pancreatic juices are a complex mixture of several enzymes in a bicarbonate-rich alkaline solution - it helps to neutralize acidic chyme and provide an ideal working environment for digestive enzymes (enzymes for the digestion of carbs, fats, and protein)

spinal cord

the spinal cord extends downward from the brainstem and can be divided into four regions: cervical, thoracic, lumbar, and sacral spinal cord is protected by the vertebral column, which transmits nerves at the space between adjacent vertebrae sensory neurons are afferent and enter the spinal cord on the DORSAL side, motor neurons are efferent and exit the spinal cord on the VENTRAL side dorsal root ganglion contains only cell bodies of sensory neurons

microscopic bone structure

the strength of the compact bone comes from the bone matrix, which has both organic and inorganic components (organic components include collagen, glycoproteins, and other peptides; the inorganic components include calcium, phosphate, and hydroxide ions, which harden to form hydroxyapatite crystals) minerals are also stored in the bone (sodium, magnesium, and potassium) strong bones require uniform distribution of organic and inorganic materials -the bony matrix is ordered into structural units known as osteons or Haversian systems; each of these osteons contains concentric circles of bony matrix called lamellae surrounding a central microscopic channel -longitudinal channels are known as Haversian canals, while transverse channels are called Volkmann's canals - these canals contain the blood vessels, nerve fibers, and lymph vessels that maintain the health of the bone -between lamellar rings are small spaces called lacunae, which house mature bone cells called osteocytes - these lacunae are interconnected by tiny channels called canaliculi that allow for the exchange of nutrients and wastes between osteocytes and Haversian and Volkmann's canals

natural selection

the theory that certain characteristics or traits possessed by individuals within a species may help those individuals have greater reproductive success, thus passing on those traits to offspring originally proposed by charles darwin in On the Origin of Species; this theory was based on several basic tenets - organisms produce offspring, few of which survive to reproductive maturity -chance variations within individuals in a population may be heritable; if these variations give an organism even a slight survival advantage, the variation is termed favorable - individuals with a greater preponderance of these favorable variations are more likely to survive to reproductive age and produce offspring; the overall result will be an increase in these traits in future generations this level of reproductive success is termed fitness, and an organism's fitness is directly related to the relative genetic contribution of this individual to the next generation

Mendel's First Law: Law of Segregation

there are four basic tenets of the modern interpretation of Mendel's first law: 1. genes exist in alternative forms (alleles) 2. an organism has two alleles for each gene - one inherited from each parent 3. the two alleles segregate during mitosis, resulting in gametes that carry only one allele for any inherited trait 4. if two alleles of an organism are different, only one will be fully expressed and the other will be silent. the expressed allele is said to be dominant and the silent one is recessive (keep in mind that codominance and incomplete dominance are exceptions to this rule) ** the key cellular correlate to draw here is the separation of homologous chromosomes during anaphase I of meiosis; by separating - segregating - these chromosomes into different cells, each gamete carries only one allele for any given trait

Veins

thin-walled, inelastic vessels that transport blood to the heart except for the pulmonary and umbilical veins, all veins carry deoxygenated blood venules are smaller venous structures that connect capillaries to the larger veins of the body veins are able to stretch to accommodate larger volumes of blood bloodflow in most veins is upward from the lower body back to the heart, against gravity --> veins have structures to push the blood forward and prevent backflow -larger veins contain valves --> as blood flows forward in the veins, the valves open; when blood tries to move backward, the valves remain slam shut veins have a small amount of smooth muscle so there is a challenge for propelling the blood forward; veins rely on external forces to generate the pressure to push blood toward the heart (skeletal muscles)

fetal circulation

to further enhance the transfer of oxygen from maternal to fetal circulation, fetal blood cells contain fetal hemoglobin (HbF) which has a greater affinity for oxygen than maternal (adult) hemoglobin. This also assists with the transfer and retention of oxygen into the fetal circulatory system. the placental barrier also serves another function: immunity; the crossing of antibodies across the placental membrane serves as a protective function the umbilical arteries carry blood away from the fetus toward the placenta; the umbilical vein carries blood toward the fetus from the placenta * remember that oxygenation occurs at the placenta, rather than in the fetal lungs. SO umbilical arteries carries DEOXYGENATED blood and umbilical vein carries OXYGENATED blood the lungs and liver do not function within the fetus for a while so while they develop there is a shunt to actively direct blood away from these organs. the fetal circulatory system differs from the adult version by having three shunts: -the foramen ovale connects the right atrium to the left atrium, bypassing the lungs -the ductus arteriosus connects the pulmonary artery to the aorta, bypassing the lungs. -the ductus venosus connects the umbilical vein to the inferior vena cava, bypassing the liver.

fluid balance in blood

two pressure gradients are essential for maintaining a proper balance of fluid volume and solute conc between blood and the interstitium (the cells surrounding the blood vessels) --> these are opposing but related hydrostatic and osmotic (oncotic) pressures hydrostatic pressure is the force per unit area that the blood exerts against the vessel walls; it is generated by the contraction of the heart and the elasticity of the arteries, and can be measured upstream in the large arteries as blood pressure -Hydrostatic pressure pushes fluid out of the bloodstream and into the interstitium through the capillary walls osmotic pressure is the "sucking" pressure generated by solutes as they attempt to draw water into the bloodstream; because most of this osmotic pressure is attributable to plasma proteins, it is usually called oncotic pressure at the arteriole end of a capillary bed, the hydrostatic pressure (pushing fluid out) is much larger than oncotic pressure (drawing fluid in), and there is a net efflux of water from circulation -as fluid moves out of the vessels, the hydrostatic pressure drops significantly, but the osmotic pressure stays about the same -at the venule end of capillarys bed, hydrostatic pressure has dropped dropped below oncotic pressure, and there is a net influx of water back into circulation

sex-linked crosses

when considering sex-linked (X-linked) traits, a slightly different system is used to symbolize the various alleles because females have two X chromosomes and thus may be homozygous or heterozygous for a condition carried on the X chromosome; males on the other hand have only one X chromosome and are hemizygous for many genes carried on the X - this is why sex-linked traits are much more common in males; having only one recessive allele is sufficient for expression of the recessive phenotype Xh is used to indicate the presence of the disease-carrying allele

Patterns of Dominance

when only one dominant and one recessive allele exist for a given gene, there is said to be complete dominance; in this case, the presence of one dominant allele will mask the recessive allele, if present when more than one dominant allele exists for a given gene, there is codominance (AB blood) incomplete dominance occurs when a heterozygote expresses a phenotype that is intermediate between the two homozygous genotypes (neither allele is dominant and the heterozygous phenotype is a mixture of the two homozygous phenotypes)

Leukocytes

white blood cells usually comprise less than 1% of total blood volume # can increase under certain conditions where we need more WBC (like during an infection) crucial part of the immune system, acting as our defenders against pathogens, foreign cells, cancer, and other materials not recognized as self two classes of WBCs: granulocytes and agranulocytes

gastulation

zygote --> morula --> blastula --> gastrula the generation of three distinct cell layers (primary germ layers) the membrane invagination into the blastocoel is called the archenteron, which later develops into the gut. the opening of the archenteron is called the blastopore... in deuterostomes, such as humans, the blastopore develops into the anus (duo means two and you do a number two). and in protostomes, it develops into the mouth. primary germ layers: 1. outermost layer is the ectoderm, gives rise to the epidermis, hair, nails, and the epithelia of the nose, mouth, and lower anal canal. also the lens of the eye, NS, and inner ear are derived from the ectoderm 2. mesoderm is the middle layer and develops into several different systems including the musculoskeletal, circulatory, and most of the excretory systems; also gives rise to the gonads as well as the muscular and connective tissue layers of the digestive and respiratory systems + the adrenal cortex 3. endoderm is the innermost layer and forms the epithelial linings of digestive and respiratory tracts, including the lungs. Also includes the pancreas, thyroid, bladder, and distal urinary tracts.

lymphatic system function

~ Equalization of fluid distribution (drain these tissues and return the fluid to the bloodstream) ~ some protection against pathology ~ edema when the lymphatics are overwhelmed - swelling due to fluid collecting in tissue ~ Transportation of biomolecules (lacteals are small lymphatic vessels; fats that are packaged into chylomicrons by intestinal mucosal cells enter the lacteal for transport; the lymphatic fluid carrying many chylomicrons takes on a milky white appearance and is called chyle) ~ Immunity (lymph nodes are a place for antigen-presenting cells and lymphocytes to interact; B cells proliferate and mature in the lymph nodes in collections called germinal centers)