CBIO2200 Final Exam

polar covalent bond

A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.

hydrogen bonds

A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.

movements at diarthrosis

A uniaxial joint only allows for a motion in a single plane (around a single axis). The elbow joint, which only allows for bending or straightening, is an example of a uniaxial joint. A biaxial joint allows for motions within two planes. An example of a biaxial joint is a metacarpophalangeal joint (knuckle joint) of the hand. A joint that allows for the several directions of movement is called a multiaxial joint (polyaxial or triaxial joint). This type of diarthrotic joint allows for movement along three axes. The shoulder and hip joints are multiaxial joints.

primary active transport

ATP is required to move a substance across a membrane, often with the help of protein carriers, and usually against its concentration gradient. most common types involve proteins that serve as pumps Na+/K+ pump transports 3 sodium out of a cell while moving 2 potassium into the cell, creates an electrical gradient also endo/exocytosis

signal transduction at chemical synapse

Action potential arrives at the axon terminal Voltage-gated Ca2+ channels open and Ca2+ enters the axon terminal Ca2+ entry causes neurotransmitter- containing synaptic vesicles to release their contents by exocytosis Neurotransmitter diffuses across the synaptic cleft and binds to specific receptors on the postsynaptic membrane. Binding of neurotransmitter opens ion channels, resulting in graded potentials. Neurotransmitter effects are terminated by reuptake through transport proteins, enzymatic degradation, or diffusion away from the synapse.

ion

An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

synarthrosis

An immobile or nearly immobile joint. The immobile nature of these joints provide for a strong union between the articulating bones. important at locations where the bones provide protection for internal organs. Examples include sutures, and the manubriosternal joint

calcium homeostasis

Cells of the parathyroid gland have plasma membrane receptors for calcium. When calcium is not binding to these receptors, the cells release PTH, which stimulates osteoclast proliferation and resorption of bone by osteoclasts. This demineralization process releases calcium into the blood. PTH promotes reabsorption of calcium from the urine by the kidneys, so that the calcium returns to the blood. Finally, PTH stimulates the synthesis of vitamin D, which in turn, stimulates calcium absorption from any digested food in the small intestine. When blood levels of calcium get too high, the thyroid gland is stimulated to release calcitonin, which inhibits osteoclast activity and stimulates calcium uptake by the bones, but also decreases reabsorption of calcium by the kidneys. All of these actions lower blood levels of calcium. When blood calcium levels return to normal, the thyroid gland stops secreting calcitonin.

feedback system

Cycle of events: Stimulus > controlled condition > receptors send signals > control center receives input > effectors effect change > response alters the condition > returns body homeostasis.

excitatory postsynaptic potential (EPSP)

Depolarization in a postsynaptic potential causes the membrane potential to move toward threshold An electrical change (depolarization) in the membrane of a postsynaptic neuron caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more likely for a postsynaptic neuron to generate an action potential.

excitation-contraction coupling

Events in Motor Neuron (Excitation-Contraction) Voltage-gated Na+ channels open and Na+ enters the motor neuron Motor neuron depolarizes Calcium channels open ACh is released Voltage-gated Na+ channels close, K+ channels open and K+ leaves the motor neuron Motor neuron repolarizes Voltage-gated K+ channels close ACh diffuses across synaptic cleft Events in Muscle Fiber (Sliding FIlament) Ligand-gated Na+ channels are activated at the motor end plate (by ACh) Na+ floods sarcolemma through t-tubule Muscle fiber is depolarized Action potential is propagated across membrane of muscle fiber Ca2+ floods sarcoplasm, binds to troponin Troponin changes shape, tropomyosin uncovers active sites, crossbridges form Filaments slide Muscle contracts

gland structure

Exocrine glands are classified as either unicellular or multicellular. The unicellular glands are found in the mucous membranes of the small and large intestine. The multicellular exocrine glands known as serous glands form a secretory surface that secretes directly into an inner cavity. These glands line the internal cavities of the abdomen and chest and release their secretions directly into the cavities. Other multicellular exocrine glands release their contents through a tubular duct. The duct is single in a simple gland but in compound glands is divided into one or more branches. In tubular glands, the ducts can be straight or coiled, whereas tubes that form pockets are alveolar (acinar). Combinations of tubes and pockets are known as tubuloalveolar (tubuloacinar) compound glands.

ionic bond

Formed when one or more electrons are transferred from one atom to another

inhibitory postsynaptic potential (IPSP)

Hyperpolarization in a postsynaptic potential it causes the membrane potential to move away from threshold. The few positive charges in the cell body are let out and the cell becomes hyperpolarized (even more negative compared to the outside). They decrease the chance that a cell will fire.

growth hormone

Increases length of long bones, enhances mineralization, and improves bone density

calcitonin

Inhibits osteoclast activity and stimulates calcium uptake by bones

gland secretions

Merocrine is the most common type. secretions are enclosed in vesicles that move to the apical surface of the cell where the contents are released by exocytosis. Apocrine accumulates near the apical portion of the cell. That portion of the cell and its secretory contents pinch off from the cell and are released. holocrine secretion involves the rupture and destruction of the entire gland cell. The cell accumulates its secretory products and releases them only when it bursts. New gland cells differentiate from cells in the surrounding tissue to replace those lost by secretion (sebaceous)

generation of an action potential steps

Na+ channels are in resting state and voltage gated K+ channels are closed Stimulus causes depolarization to threshold Na+ channels open and further depolarize the membrane Na+ gates become "inactive" and K+ ion channels open. The outflow of K+ repolarizes membrane K+ are still open and Na+ channels are in resting state Steps 3 and 4 are absolutely refractory because 3) the Na+ channel are ALREADY open 4) the Na+ gates are inactive so they can't be open right then Step 5 is relatively refractory because Na+ are in a resting state and can be activated\again but only if it is a stronger stimulus to make up for the hyperpolarization Absolute refractory: Depolarization and repolarization; another action potential wont start Relative refractory: Hyperpolarization; action potential can be caused by a super strong stimulus

sex hormones

Promote osteoblastic activity and production of bone matrix; responsible for adolescent growth spurt; promote conversion of epiphyseal plate to epiphyseal line

saltatory conduction

Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.

calcitriol

Stimulates absorption of calcium and phosphate from digestive tract

thyroxine

Stimulates bone growth and promotes synthesis of bone matrix

parathyroid hormone

Stimulates osteoclast proliferation and resorption of bone by osteoclasts; promotes reabsorption of calcium by kidney tubules; indirectly increases calcium absorption by small intestine

neuron

The cell body contains the nucleus and most of the major organelles. But what makes special is that they have many extensions of their cell membranes, which are generally referred to as processes. The other processes of the neuron are dendrites, which receive information from other neurons at specialized areas of contact called synapses. Information flows through a neuron from the dendrites, across the cell body, and down the axon. This gives the neuron a polarity—meaning that information flows in this one direction.

osteoclast

The cell responsible for bone resorption, or breakdown found on bone surfaces, are multinucleated, and originate from monocytes and macrophages, white blood cells, not osteogenic cells. continually breaking down old bone while osteoblasts are continually forming new bone. The ongoing balance is responsible for the constant but subtle reshaping of bone.

protein synthesis

The first step is the transcription of mRNA from a DNA gene in the nucleus. The RNAs migrate from the nucleus into the cytoplasm. Prior to the beginning of the protein synthesis, all of the components are assembled in the ribosome. initiation starts by the AUG codon on mRNA. The AUG codon signals both the interaction of the ribosome with m-RNA and also the tRNA with the anticodons Elongation of the peptide begins as various tRNA's read the next codon. When the stop signal on mRNA is reached, the protein synthesis is terminated. The last amino acid is hydrolyzed from its t-RNA. The peptide chain leaves the ribosome.

generation of an action potential

This starts with a channel opening for Na+ in the membrane. Because the concentration of Na+ is higher outside the cell than inside, ions will rush into the cell by the concentration gradient. The resting potential is the state of the membrane at a voltage of -70 mV, so the sodium cation entering the cell will cause it to become less negative. This is known as depolarization, membrane potential moves toward zero. The concentration gradient for Na+ is so strong that it will continue to enter the cell even after the membrane potential has become zerE.The membrane potential will reach +30 mV by the time sodium has entered the cell. As the membrane potential reaches +30 mV, other voltage-gated channels are opening in the membrane specific for the potassium ion. A concentration gradient acts on K+. As K+ starts to leave the cell, taking a positive charge with it, the membrane potential begins to move back toward its resting voltage. This is called repolarization, meaning that the membrane voltage moves back toward the -70 mV value of the resting membrane potential. Repolarization returns the membrane potential to the -70 mV but it actually overshoots that value. Potassium ions reach equilibrium when the membrane voltage is below -70 mV, so a period of hyperpolarization occurs while the K+ channels are open. Those K+ channels are slightly delayed in closing, accounting for this short overshoot.

sliding filament mechanism

To initiate muscle contraction, tropomyosin has to expose the myosin-binding site on an actin filament to allow cross-bridge formation between the actin and myosin microfilaments. The first step in the process of contraction is for Ca++ to bind to troponin so that tropomyosin can slide away from the binding sites on the actin strands. This allows the myosin heads to bind to these exposed binding sites and form cross-bridges. Calcium is released and clears the actin binding sites. Myosin head attaches to actin (High energy ADP + P configuration) Power stroke; myosin head pivots pulling the actin filament toward the center The cross bridge detaches when a new ATP binds with the myosin Cocking of the myosin head occurs when ATP -> ADP + P. Another cross bridge can form.

secondary active transport

When active transport powers the transport of another substance Form of active transport which does not use ATP as an energy source; rather, transport is coupled to ion diffusion down a concentration gradient established by primary active transport.

non-polar covalent bond

a covalent bond in which the bonding electrons are shared equally by the bonded atoms resulting in a balanced distribution of electrical charge

arachnoid mater

a membrane of thin fibrous tissue that forms a loose sac around the CNS. Beneath the arachnoid is a thin, filamentous mesh called the arachnoid trabeculae, which looks like a spider web, giving this layer its name.

carbohydrate

a molecule composed of carbon, hydrogen, and oxygen; in most, hydrogen and oxygen are found in the same two-to-one relative proportions they have in water. In fact, the chemical formula for a "generic" molecule of carbohydrate is (CH2O)n. saccharides or "sugars"

Creatine phosphate

a molecule that can store energy in its phosphate bonds. In a resting muscle, excess ATP transfers its energy to creatine, producing ADP and creatine phosphate. This acts as an energy reserve that can be used to quickly create more ATP. transfers its phosphate back to ADP to form ATP and creatine. This reaction is catalyzed by the enzyme creatine kinase and occurs very quickly; only provide approximately 15 seconds worth of energy, at which point another energy source has to be used

acid

a substance that releases hydrogen ions (H+) in solution thus increasing the H+ concentration strong ____ are compounds that release all of their H+ in solution; that is, they ionize completely. Weak ____ do not ionize completely; that is, some of their hydrogen ions remain bonded within a compound in solution.

base

a substance that releases hydroxyl ions (OH-) in solution, or one that accepts H+ already present in solution A substance that decreases the hydrogen ion concentration in a solution. strong ___ release most or all of their hydroxyl ions; weak __ release only some hydroxyl ions or absorb only a few H+.

spongy bone

also known as cancellous bone, contains osteocytes housed in lacunae, but they are not arranged in concentric circles. Instead, the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae spaces of the trabeculated network provide balance to the dense and heavy compact bone by making bones lighter so muscles can move more easily. spaces in some spongy bones contain red marrow, protected by the trabeculae, where hematopoiesis occurs.

Glycolysis

an non-oxygen-dependent process that breaks down glucose to produce ATP; cannot generate ATP as quickly as creatine phosphate. results in a slower rate of ATP availability to the muscle. The sugar. The breakdown of one glucose molecule produces two ATP and two molecules of pyruvic acid, which can be used in aerobic respiration or when oxygen levels are low, converted to lactic acid If oxygen is available, pyruvic acid is used in aerobic respiration. However, if oxygen is not available, pyruvic acid is converted to lactic acid, which may contribute to muscle fatigue. This conversion allows the recycling of the enzyme NAD+ from NADH, which is needed to continue. cannot be sustained for very long (approximately 1 minute of muscle activity), but it is useful in facilitating short bursts of high-intensity output. producing a net gain of two ATPs per molecule of glucose, and the end product of lactic acid, which may contribute to muscle fatigue as it accumulates.

cartilaginous (structural classification)

bones are joined by hyaline cartilage or fibrocartilage Synchondroses— hyaline cartilage (epiphyseal plate) Symphyses— fibrocartilage (pubic symphysis)

aerobic respiration

breakdown of glucose or other nutrients in the presence of oxygen (O2) to produce carbon dioxide, water, and ATP. Approximately 95 percent of the ATP required for resting or moderately active muscles, which takes place in mitochondria. The inputs include glucose circulating in the bloodstream, pyruvic acid, and fatty acids. much more efficient than anaerobic glycolysis, producing approximately 36 ATPs per molecule of glucose. cannot be sustained without a steady supply of O2 to the skeletal muscle and is much slower.

connective tissue

cells are dispersed in a matrix, major component of the matrix is a ground substance often crisscrossed by protein fibers three characteristic components: cells, large amounts of amorphous ground substance, and protein fibers. support, connect, and protect other tissues/organs Connective tissue proper includes loose connective tissue and dense connective tissue. Both tissues have a variety of cell types and protein fibers suspended in a viscous ground substance. Dense connective tissue is reinforced by bundles of fibers that provide tensile strength, elasticity, and protection. In loose connective tissue, the fibers are loosely organized, leaving large spaces in between. Supportive connective tissue—bone and cartilage—provide structure and strength to the body and protect soft tissues. A few distinct cell types and densely packed fibers in a matrix characterize these tissues. In bone, the matrix is rigid and described as calcified because of the deposited calcium salts. In fluid connective tissue, in other words, lymph and blood, various specialized cells circulate in a watery fluid containing salts, nutrients, and dissolved proteins.

voltage-gated channel

channel that responds to changes in the electrical properties of the membrane in which it is embedded. Normally, the inner portion of the membrane is at a negative voltage. When that voltage becomes less negative, the channel begins to allow ions to cross the membrane

nervous tissue

characterized as being excitable and capable of sending and receiving electrochemical signals that provide the body with information. Two main classes of cells: the neuron and neuroglia. Neurons propagate information via electrochemical impulses, called action potentials, which are biochemically linked to the release of chemical signals. Neuroglia play an essential role in supporting neurons and modulating their information propagation. A neuron displays: a large cell body branched out into short extensions called dendrites, which receive chemical signals from other neurons, and a long tail called an axon, which relays signals away from the cell to other neurons, muscles, or glands. Astrocyte cells are abundant in the CNS. have many functions, including regulation of ion concentration in the intercellular space, uptake and/or breakdown of some neurotransmitters, and formation of the blood-brain barrier, the membrane that separates the circulatory system from the brain. Microglia protect the nervous system against infection but are not nervous tissue because they are related to macrophages. Oligodendrocyte cells produce myelin in the CNS while the Schwann cell produces myelin in the PNS

muscle tissue

characterized by properties that allow movement. are excitable; they respond to a stimulus. They are contractile, meaning they can shorten and generate a pulling force. When attached between two bones, contractions cause the bones to move. Some movement is voluntary, which means it is under conscious control. Other movements are involuntary, meaning they are not under conscious control, such as the contraction of your pupil in bright light. skeletal, smooth, and cardiac

ATP

composed of a ribose sugar, an adenine base, and three phosphate groups. classified as a high energy compound because the two covalent bonds linking its three phosphates store a significant amount of potential energy. In the body, the energy released from these high energy bonds helps fuel the body's activities, from muscle contraction to the transport of substances in and out of cells to anabolic chemical reactions.

epidermis (tissue)

composed of keratinized, stratified squamous epithelium. It is made of four or five layers of epithelial cells, depending on its location in the body. It does not have any blood vessels within it. From deep to superficial, these layers are the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum.

bone cells

contains a relatively small number of cells entrenched in a matrix of collagen fibers that provide a surface for inorganic salt crystals to adhere.

dermis (tissue)

contains blood and lymph vessels, nerves, and other structures, such as hair follicles and sweat glands. papillary layer is made of loose, areolar connective tissue, which means the collagen and elastin fibers of this layer form a loose mesh the reticular layer is composed of dense, irregular connective tissue

slow oxidative

contract relatively slowly and use aerobic respiration (oxygen and glucose) to produce ATP. This type of muscle fiber is described as red, has a slow rate of fatigue, has slow contraction, is aerobic, has a high myoglobin content, is the first to be recruited for contraction and is associated with endurance type activities

graded action potential

either they are depolarizing or hyperpolarizing. For a membrane at the resting potential, a ______ represents a change in that voltage either above -70 mV or below -70 mV. Depolarizing _____ are often the result of Na+ or Ca2+ entering the cell. Both of these ions have higher concentrations outside the cell than inside; because they have a positive charge, they will move into the cell causing it to become less negative relative to the outside. Hyperpolarizing graded potentials can be caused by K+ leaving the cell or Cl- entering the cell. If a positive charge moves out of a cell, the cell becomes more negative; if a negative charge enters the cell, the same thing happens. Depolarization in a postsynaptic potential is called an excitatory postsynaptic potential (EPSP) because it causes the membrane potential to move toward threshold. Hyperpolarization in a postsynaptic potential is an inhibitory postsynaptic potential (IPSP) because it causes the membrane potential to move away from threshold.

fast glycolytic

fast contractions and primarily use anaerobic glycolysis. fatigue more quickly than the others. Most skeletal muscles in a human contain(s) all three types, although in varying proportions. described as white, has a fast rate of fatigue, fast contraction, is anaerobic, has a low myoglobin content, is last to be recruited for contraction and is associated with fast powerful contractions, such as hitting a baseball

structural classification of joints

fibrous, cartilaginous, synovial

diarthrosis

freely mobile joint These types of joints include all synovial joints of the body, which provide the majority of body movements. Most diarthrotic joints are found in the appendicular skeleton and thus give the limbs a wide range of motion. These joints are divided into three categories, based on the number of axes of motion provided by each.

ependymal cell

glial cell type in the CNS responsible for producing cerebrospinal fluid

oligodendrocyte

glial cell type in the CNS that provides the myelin insulation for axons in tracts

microglia

glial cell type in the CNS that serves as the resident component of the immune system

satellite cell

glial cell type in the PNS that provides support for neurons in the ganglia

schwann cell

glial cell type in the PNS that provides the myelin insulation for axons in nerves

astrocyte

glial cell type of the CNS that provides support for neurons and maintains the blood-brain barrier

stratum granulosum

grainy appearance due to further changes to the keratinocytes as they are pushed from the stratum spinosum. The cells (three to five layers deep) become flatter, their cell membranes thicken, and they generate large amounts of the proteins keratin, which is fibrous, and keratohyalin, which accumulates as lamellar granules within the cells the nuclei and other cell organelles disintegrate as the cells die, leaving behind the keratin, keratohyalin, and cell membranes that will form the stratum lucidum, the stratum corneum, and the accessory structures of hair and nails.

negative feedback system

has three basic components: sensor monitors a physiological value. This value is reported to the control center. control center compares the value to the normal range. If the value deviates too much from the set point, then the control center activates an effector. effector causes a change to reverse the situation and return the value to the normal range. reverses change in a controlled condition ex: blood pressure and temp.

fast oxidative

have fast contractions and primarily use aerobic respiration, but because they may switch to anaerobic respiration (glycolysis), can fatigue more quickly than SO fibers described as red to pink, has a intermediate rate of fatigue, has fast contraction, is aerobic and anaerobic, has a high myoglobin content, is second to be recruited for contraction and is associated with activities such as walking and sprinting. These fibers "can do either"

positive feedback system

intensifies a change in the body's physiological condition rather than reversing it. A deviation from the normal range results in more change, and the system moves farther away from the normal range. normal only when there is a definite end point. example: childbirth and blood clotting

amphiarthrosis

joint that has limited mobility. An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae called an intervertebral disc. Another example is the pubic symphysis of the pelvis. This is a cartilaginous joint in which the pubic regions of the right and left hip bones are strongly anchored to each other by fibrocartilage.

skeletal muscle cell

long, multinucleated cells. The membrane of the cell is the sarcolemma; the cytoplasm of the cell is the sarcoplasm. The sarcoplasmic reticulum (SR) is a form of endoplasmic reticulum. composed of myofibrils. The striations are created by the organization of actin and myosin resulting in the banding pattern of myofibrils. voluntary

glands

made up of one or more cells modified to synthesize and secrete chemical substances. Most consist of groups of epithelial cells. can be classified as an endocrine, a ductless gland that releases secretions (hormones) directly into surrounding tissues and fluids, or an exocrine gland whose secretions (mucous, sweat, saliva) leave through a duct that opens directly, or indirectly, to the external environment

microscopic bone tissue

microscopic structural unit of compact bone is called an osteon, or Haversian system. composed of concentric rings of calcified matrix called lamellae. Running down the center of each osteon is the central canal, or Haversian canal, which contains blood vessels, nerves, and lymphatic vessels. The osteocytes are located inside spaces called lacunae (singular = lacuna), found at the borders of adjacent lamellae. canaliculi connect with the canaliculi of other lacunae and eventually with the central canal. This system allows nutrients to be transported to the osteocytes and wastes to be removed from them.

stratum corneum

most superficial layer of the epidermis and is the layer exposed to the outside environment. The increased keratinization of cells in this layer gives it its name. 15 to 30 layers of cells. This dry, dead layer helps prevent the penetration of microbes and the dehydration of underlying tissues, and provides a mechanical protection against abrasion for the more delicate, underlying layers. shed periodically and are replaced by cells pushed up from the stratum granulosum. layer is replaced during a period of about 4 weeks.

DNA

nucleotide that stores genetic information. contains deoxyribose plus one phosphate group and one nitrogen-containing base. The "choices" of base are adenine, cytosine, guanine, and thymine.

lipid

one of a highly diverse group of compounds made up mostly of hydrocarbons. The few oxygen atoms they contain are often at the periphery of the molecule. Their nonpolar hydrocarbons make them hydrophobic. In water, lipids form an emulsion, which is the term for a mixture of solutions that do not mix well.

isotope

one of the different forms of an element, distinguished from one another by different numbers of neutrons. Atoms of the same element that have different numbers of neutrons

ligand-gated channel

opens because a signaling molecule, a ligand, binds to the extracellular region of the channel. This type of channel is also known as an ionotropic receptor because when the ligand, known as a neurotransmitter in the nervous system, binds to the protein, ions cross the membrane changing its charge

mechanically gated channel

opens because of a physical distortion of the cell membrane. Many channels associated with the sense of touch (somatosensation) are mechanically gated. For example, as pressure is applied to the skin, these channels open and allow ions to enter the cell. Similar to this type of channel would be the channel that opens on the basis of temperature changes, as in testing the water in the shower

protein

organic molecule composed of amino acids linked by peptide bonds. include the keratin in the epidermis of skin, the collagen found in the dermis of skin, in bones, and in the meninges that cover the brain and spinal cord. components of many of the body's chemicals, including digestive enzymes, antibodies, the neurotransmitters that neurons use to communicate with other cells, and the peptide-based hormones. contain nitrogen (N), and many contain sulfur (S), in addition to carbon, hydrogen, and oxygen.

osteocyte

primary cell of mature bone and the most common type of bone cell. located in a space called a lacuna and is surrounded by bone tissue. maintain the mineral concentration of the matrix via the secretion of enzymes. Like osteoblasts, lack mitotic activity. They can communicate with each other and receive nutrients via long cytoplasmic processes that extend through canaliculi channels within the bone matrix.

facilitated diffusion

process used for those substances that cannot cross the lipid bilayer due to their size, charge, and/or polarity. movement is restricted to protein channels and specialized transport mechanisms in the membrane. down gradient, no energy used

epithelial tissue

provide the body's first line of protection from physical, chemical, and biological wear and tear. act as gatekeepers of the body controlling permeability and allowing selective transfer of materials across a physical barrier. Epithelial tissues are classified according to the shape of the cells and number of the cell layers formed Functions: protection, absorption, excretion, secretion, filtration and sensory reception. Avascular (lacks own blood supply)

leakage channel

randomly gated, meaning that it opens and closes at random, hence the reference to leaking. There is no actual event that opens the channel; instead, it has an intrinsic rate of switching between the open and closed states. contribute to the resting transmembrane voltage of the excitable membrane

RNA

ribose-containing nucleotide that helps manifest the genetic code as protein. contains ribose, one phosphate group, and one nitrogen-containing base, but the "choices" of base for RNA are adenine, cytosine, guanine, and uracil.

continuous conduction

slow propagation of an action potential along an unmyelinated axon owing to voltage-gated Na+ channels located along the entire length of the cell membrane

stratum lucidum

smooth, seemingly translucent layer of the epidermis located just above the stratum granulosum and below the stratum corneum. This thin layer of cells is found only in the thick skin of the palms, soles, and digits. The keratinocytes that compose the stratum lucidum are dead and flattened

buffer

solution of a weak acid and its conjugate base. can neutralize small amounts of acids or bases minimizes changes in pH Homeostatic mechanisms keep the pH of blood within narrow range. This is critical, because fluctuations—either too acidic or too alkaline—can lead to life-threatening disorders.

smooth muscle cell

spindle-shaped and have a single nucleus and they produce their own connective tissue, endomysium Although they do not have striations and sarcomeres, do have actin and myosin contractile proteins, and thick and thin filaments. These thin filaments are anchored by dense bodies. Calcium ions are supplied by the SR in the fibers and by sequestration from the extracellular fluid through membrane indentations called calveoli. involuntary muscle

stratum spinosum

spiny in appearance due to the protruding cell processes that join the cells via a structure called a desmosome. The desmosomes interlock with each other and strengthen the bond between the cells. Langerhans cell- acts as a macrophage by engulfing bacteria, foreign particles, and damaged cells that occur in this layer keratinocytes- begin the synthesis of keratin and release a water-repelling glycolipid that helps prevent water loss from the body, making skin relatively waterproof.

cardiac muscle cell

striated and organized into sarcomeres, possessing the same banding organization as skeletal muscle. However, shorter than skeletal muscle fibers and usually contain only one nucleus, which is located in the central region of the cell. also possess many mitochondria and myoglobin, as ATP is produced primarily through aerobic metabolism. extensively branched and are connected to one another at their ends by intercalated discs allows the muscle cells to contract in a wave-like pattern so that the heart can work as a pump.

glial cells

supportive cells of nervous system that guide growth of new neurons; forms myelin sheath; holds neuron in place; provides nourishment and removes waste CNS: astrocyte, oligodendrocyte, microglia, and ependymal cell PNS: satellite cell and schwann cell

functional classification of joints

synarthrosis amphiarthrosis diarthrosis

synovial (structural classification)

the articulating surfaces of the bones are not directly connected, but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid. Synovial joints allow for free movement between the bones and are the most common joints of the body.

osteoblast

the bone cell responsible for forming new bone and is found in the growing portions of bone, including the periosteum and endosteum. do not divide. synthesize and secrete the collagen matrix and calcium salts. As the secreted matrix surrounding the osteoblast calcifies, the osteoblast become trapped within it;

stratum basale

the deepest epidermal layer; attaches the epidermis to the basal lamina, below which lie the layers of the dermis. The cells in the stratum basale bond to the dermis via intertwining collagen fibers, referred to as the basement membrane. basal cell- cuboidal-shaped stem cell that is a precursor of the keratinocytes of the epidermis Merkel cell- receptor and is responsible for stimulating sensory nerves that the brain perceives as touch melanocyte- a cell that produces the pigment melanin

compact bone

the denser, stronger of the two types of bone tissue. It can be found under the periosteum and in the diaphyses of long bones, where it provides support and protection. (see also microscopic bone tissue)

osmosis

the diffusion of water through a semipermeable membrane down its concentration gradient. If a membrane is permeable to water, though not to a solute, water will equalize its own concentration by diffusing to the side of lower water concentration (and thus the side of higher solute concentration) A hypertonic solution has a solute concentration higher than another solution. An isotonic solution has a solute concentration equal to another solution. A hypotonic solution has a solute concentration lower than another solution.

diffusion

the movement of particles from an area of higher concentration to an area of lower concentration until no more concentration gradient remains. allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, no energy used

translation

the process of synthesizing a chain of amino acids called a polypeptide. Initiation takes place with the binding of a ribosome to an mRNA transcript. The elongation stage involves the recognition of a tRNA anticodon with the next mRNA codon in the sequence. Once the anticodon and codon sequences are bound (remember, they are complementary base pairs), the tRNA presents its amino acid cargo and the growing polypeptide strand is attached to this next amino acid. This attachment takes place with the assistance of various enzymes and requires energy. The tRNA molecule then releases the mRNA strand, the mRNA strand shifts one codon over in the ribosome, and the next appropriate tRNA arrives with its matching anticodon. This process continues until the final codon on the mRNA is reached which provides a "stop" message that signals termination of translation

atom

the smallest quantity of an element that retains the unique properties of that element. smallest component of an element having the chemical properties of the element

transcription

the synthesis of a strand of mRNA that is complementary to the gene of interest. Stage 1: Initiation. A region at the beginning of the gene called a promoter triggers the start. Stage 2: Elongation. Starts when RNA polymerase unwinds the DNA segment. One strand, referred to as the coding strand, becomes the template with the genes to be coded. The polymerase then aligns the correct nucleic acid (A, C, G, or U) with its complementary base on the coding strand of DNA. RNA polymerase is an enzyme that adds new nucleotides to a growing strand of RNA. This process builds a strand of mRNA. Stage 3: Termination. When the polymerase has reached the end of the gene, one of three specific triplets (UAA, UAG, or UGA) codes a "stop" signal, which triggers the enzymes to terminate and release the mRNA transcript. modified after

dura mater

thick fibrous layer and a strong protective sheath over the entire brain and spinal cord. It is anchored to the inner surface of the cranium and vertebral cavity.

osteogenic cell

undifferentiated with high mitotic activity and they are the only bone cells that divide. Immature osteogenic cells are found in the deep layers of the periosteum and the marrow. They differentiate and develop into osteoblasts

fibrous (structural classification)

where the adjacent bones are united by fibrous connective tissue