Physiology Exam 3

EPSP

(excitatory post synaptic potential): results when the membrane is depolarized (made more positive than the resting membrane potential -65 mv), ions involved are Na+ (action potential) and Ca 2+ (vesicle fusion), multiple EPSPs result in an action potential, more strongly through multiple in a row in the same location, common neurotransmitters are Ach and glutamate

Define hormone, endocrine gland, neurosecretory tissue, negative feedback, tropic hormone, anti-diuretic hormone (ADH), oxytocin, releasing hormones, inhibiting hormones, endocrine axis, antagonism, synergism, corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH), glucocorticoids, aldosterone, insulin, glucagon, and diabetes mellitus.

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Define reflex arc, ganglia, nerves, catecholamines, and muscarinic and nicotinic receptors.

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Define sarcomere, actin, myosin, tropomyosin, troponin, sarcolemma, t-tubules, sarcoplasmic reticulum, dihydropyridine receptor (DHPR), ryanodine receptor (RyR), twitch fibers, tonic fibers, and sonic fibers.

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Define synapse, synaptic cleft, gap junction, depolarize, hyperpolarize, post-synaptic potential, agonist, antagonist, synaptic plasticity, facilitation, summation, neurotransmitter, and synaptic vesicle.

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Describe how the nervous system and endocrine system help to regulate the mammalian stress response, water and salt balance, and nutrient metabolism, including relevant hormones and tissues, physiological mechanisms of action, and mechanisms of regulation.

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Distinguish the key properties and components of (1) electrical vs. chemical synapses, (2) ionotropic vs. metabotropic chemical synapses.

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Explain the mechanisms of inhibitory (IPSPs) and excitatory synaptic potentials (EPSPs) with respect to resting potential, ions involved, de- and hyperpolarization, summation, and the production of action potentials.

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Compare and contrast endocrine system and nervous system signaling.

-Both the nervous and endocrine system send to cell to cell messages via chemical messengers -Nervous system messaging is directed at more specific targets -Endocrine communication is slower -Nervous system signals are shorter lasting -Endocrine system signals usually travel a farther distance between secretory and receiver cells -Neural transmission: fast addressed signals through neurons -endocrine transmission: slow broadcast signaling through the bloodstream

post-synaptic potential

-EPSP (excitatory post-synaptic potential): local depolarization of the membrane, Na+ and Ca2+ channels open, Ach in muscles and glutamate in neurons are excitatory neurotransmitters -IPSP (inhibitory post-synaptic potential): local hyperpolarization (or anything below RMP) of the membrane at the post-synaptic cleft, K+ and Cl- channels open, glycine and GABA are inhibitory neurotransmitters in neurons (muscles have no inhibitory neurotransmitters, except Ach in the heart muscle)

Describe the major neurotransmitters Acetylcholine, GABA, glutamate, and glycine, whether they are inhibitory or excitatory (or other), where they are produced and recycled.

-acetylcholine (Ach): excitatory neurotransmitter in muscles, activates Na+ and Ca 2+ channels, is recycled from the post-synaptic membrane through acetylcholinesterase, which breaks it apart and then it is reabsorbed into the presynaptic membrane and re put together into Ach, ionotropic -GABA: inhibitory neurotransmitter, activates K+ and Cl- channels, can be released or reuptaken by a nearby cell -glutamate: excitatory neurotransmitter in neurons-neuron, activates Ca 2+ and Na+ channels, amino acid neurotransmitter produced in the body and recycled -glycine: inhibitory neurotransmitter in neuron-neuron, activates Cl- and K+ channels, can be produced or recycled

electrical vs chemical synapses

-electrical synapse: cytoplasm of two neurons is connected via gap junctions, allowing ions of the AP to diffuse directly into other effector cells; faster, bidirectional, excitatory only -chemical synapses: signals are sent between two nuerons via chemical neurotransmitters that bind to receptors on the post-synaptic membrane; unidirectional, can be excitatory or inhibitory, have plasticity (its strength varies)

ionotropic vs metabotropic receptors

-ionotropic receptors: have ligand gated channel receptors, five subunits around an ion channel, action is generated by opening the ion channel through a change in the membrane potential, no second messenger, has fast EPSP or IPSP -metabotropic receptors: g-protein coupled receptor molecule (protein with seven transmembrane segments, g-protein activated causes metabolic cascade with second messengers, has slow PSP; can activate an ion channel or a signaling cascade

Describe how the nervous system and endocrine system help to regulate the mammalian stress response, water and salt balance, and nutrient metabolism, including relevant hormones and tissues, physiological mechanisms of action, and mechanisms of regulation.

-mammalian stress response is a suite of physiological responses geared toward short term survival in a threatening situation -sympathetic nervous system releases norepinephrine and epinephrine, increasing heart rate and blood pressure, relaxing airways, constricting blood vessels, inhibiting digestion, increasing glucagon, increasing fat catabaloism -endocrine system HPA activates CRH (hypothalamus), which activates ACTH (anterior pituitary), which activates glucocorticoids (adrenal cortex), which enhances the earlier effects of the sympathetic nervous system, delivers nutrients to the blood to convert to sugar, promotes liver glucogenesis, ADH conserves water and fluid retention by vasopressin stimulating the kidney to retain fluid by concentrating urine, aldosterone binds intracellularly and turns on transcription factor of Na/K pump activity to change it so na+ is conserved leading to retention of fluid, both of which lead to increased volume and blood pressure

Describe how the endocrine system acts via "axes" and can be regulated by the nervous system and negative feedback.

-pituitary "master" gland: located at base of hypothalamus secrete hormones that regulate homeostasis -posterior pituitary gland: neurohypophysis, releases ADH (vasopressin, water retention in kidneys, vasocontristcion), and oxytocin (uterus contraction during birth, lactation, bonding) -anterior pituitary gland: adenohypophysis, acts on nonendocrine tissues through growth hormone, prolactin (lactation), MSH (skin darkening), and beta endorphins (excitement and pain relief), also acts on other endocrine tissues through tropic hormones such as ACTH (stimulates adrenal cortex to release glucocorticoids), TSH (stimulates thyroid to release thyroxins), FSH (stimulates gonads to release estrogens and testosterone) and LH (similar to FSH) -HPA axis: neural output (stress, circadian clock) causes hypothalamus to secrete CRH, which stimulates anterior pituitary to release ACTH and posterior pituitary to release ADH (synergistic with ACTH) which stimulates the adrenal cortex to release glucorticoids that increase nutrient metabolism and fat catabolism; increased concentration of glucocorticoids in bloodstream inhibits synthesis of ACTH and CRH, products inhibit synthesis of more products

Describe the sliding filament theory of muscle contraction, including the sequence of molecular interactions leading to contraction.

-sarcomeres bound to each other linearly, during contraction, actin and myosin filaments slide along each other, causing the muscle to contract 1) actin binding site bound to myosin, no ATP available 2) ATP binds to ATP binding site on myosin head, mysoin ATPase hydrolizes it into ADP and a free phosphate, energy from reaction transferred to cross bridge 3) myosin head moves to a cocked position, finding next binding site over 4) release of phosphate causes power stroke which moves actin filament closer to the center of the sarcomere 5) ADP is released from myosin head, causing myosin to be tightly bound to actin (rigor)

neurotransmitter

-signals sent between neurons through chemicals that bind to receptors on the post-synaptic membrane -a single neuron can only release on type of neurotransmitter -a neuron can receive several types of neurotransmitters

Compare and contrast the three major classes of hormones and give examples of each.

-steroid hormones: cholesterol derivatives, lipid soluble, secreted by gonads and adrenal cortex, target receptors are intracellular, are synthesized as needed, not stored (i.e., testosterone, estrogen, aldosterone, cortisol) -peptide hormones: peptide chains, water soluble, released by many glands (anterior pituitary gland), receptors are extracellular, stored in secretory vesicles and released via exocytosis (insulin) -amine hormones: tyrosine (catecholamines) and tryptophan (melatonin), secreted few glands/organs (adrenal medulla, thryoid) (i.e. epinephrine)

Compare and contrast the structure and function of striated and smooth muscle tissue.

-striated muscle tissue has appearance of alternating light and dark bands (contractile proteins organized as sarcomeres), makes up sekletal and cardiac tissue in vertebrates -smooth muscle tissue: has contractile proteins but are not organized in sarcomeres so it does not appear striated, lines gI tract, blood vessels, respiratory tract, urinary tract (involuntary muscles), no troponin, more actin filaments, actin and mysoin organized in bundles around the cell, when it contracts the filaments slide along each other, making it globular, contain gap junctions and are innervated by the ANS, neurotransmitter release contracts nearby fibers through connected cytosols

Compare and contrast the structure and function of the sympathetic and parasympathetic nervous systems, giving examples of effects on systems, such as the cardiovascular, respiratory, and digestive, and including the major neurotransmitters, acetylcholine and norepinephrine.

-sympathetic nervous system: part of the autonomic nervous system, mediates the fight or flight response, dilates pupils, contracts blood vessels, relaxes airways, stimulates sweat glands, inhibits digestion, relaxes bladder, increases blood pressure, acetylcholine is excitatory at the ganglion, norepinephrine is excitatory at the effector cells -parasympathetic nervous systems: part of the autonomic nervous system, mediates the "rest and digest" functions, brings the body back from sympathetic function, constricts airways, slows heartbeat, stimulates digestion, dilates blood vessels, decreases blood pressure, acetylcholine is excitatory at the preganglionic neuron of the parasympathetic system but inhibitory in the effector cells

control of nutrient metabolism

-when blood glucose levels are high, insulin is released by beta pancreatic cells to promote the liver and skeletal muscles to uptake glucoseg/glycogen and store, leading to normal blood glucose levels -when blood glucose levels are high, glucagon is released by alpha pancreatic cells to promote the liver to break down glycogen into glucose and release it into the bloodstream -during a high carb meal, insulin is high because glucose is high -during a high protein meal, insulin is high to control amino acid levels but glucagon is also high because of lack of blood glucose -insulin and glucagon are antagonistic -insulin always tracks glucose -high glucose levels lead to high ATP due to intake of glucose via cellular respiration, high ATP to ADP ratio closes k+ channels depolarizing the cell, causing Ca 2+ cells to open and insulin to released from vesicles via exoctyosis as well as activates insulin gene expression, insulin binds to insulin receptors, opening glucose channels and transforming them into glycogen, pyruvic acid, and free fatty acids

water and salt balance

-when blood volume is low, ADH released by the posterior pituitary gland will stimulate membrane aquaporin channels allowing water to travel back into the bloodstream via osmosis -renin is secreted when blood pressure is low, causing secretion of aldosterone from the adrenal cortex, which binds intracellularly and turns on transcription factors that change Na/K pump activity, allowing Na+ to escape back into the bloodstream, water follows by osmosis, preventing Na+ from leaving through urine

Describe the mechanism of neurotransmitter release via vesicles in response to membrane potential and ion flux.

1) arrival of action potential stimulates opening of Ca2+ channels, causing influx of Ca 2+ into the cytosol of the presynaptic neuron 2) Ca2+ triggers vesicle fusion and neurotransmitter release through exocytosis 3) neurotransmitter binds to the receptor on the post-synaptic membrane either by: a) binding to ionotropic receptors (ligand gates ion channels which increase permeability of ions) and inducing fast chemical synaptic transmission or b) binding to metabotropic receptors on the post synaptic membrane (g-protein coupled receptors ) which results in a signaling cascade and slow chemical synaptic transmission) 4) the transmission is then inactivated by a) ion channel deactivation by change in conformation from desensitization, b) enzymatic decay of the neurotransmitter in the synaptic cleft, c) uptake of neurotransmitter by the nearby cell, or d) endocytic internalization of the receptor

Explain how excitation and contraction of myocytes are coupled, beginning with motor neuron stimulation.

1) release of Ach from the motor neuron binds to Ach, allowing Na+ to come in, and K+ to leave, AP travels down the t-tubule 2) the RyR-DHPR complex dissociates, allowing Ca 2+ to flux from the SR to the cytosol 3) Ca 2+ binds to troponin, causing tropomyosin to move off the myosin binding sites on the actin molecule, allowing actin-myosin cross bridging 4) AP is terminated through acetylcholinesterase allowing for reuptake into the synaptic cleft 5) Ca 2+ left in the cytosol is drawn back into the SR through the ATP transporter 6) striated muscles relax when Ca 2+ is removed from the cytosol

reflex arc

A relatively direct connection between a sensory neuron and a motor neuron that allows an extremely rapid response to a stimulus, often without conscious brain involvement.

dihydripiyridine receptor

DHPR located on t tubule connecting it to the SR, not a channel, when bound to RyR, SR cannot release Ca 2+ into the cytosol

Explain how adaptations in vertebrate myocytes that can impact twitch speed of the fibers, and compare those to the mechanism of contraction in insect asynchronous flight muscle.

Factors that make sonic fibers so fast are myosin isoforms capable of rapid cross bridge attachment/release, troponin isoforms with low Ca2+ affinity leadi -AFMs increase contraction rates by uncouple muscle contraction with action potentials, it is the stretch of the muscle that allows the flight muscle to keep twitching -there is one action potential that initiates one big round of contraction -two different antagonist muscles required for up-down contraction motion -muscles do not pump Ca 2+ back into the SR with each contraction, saving ATP

endocrine gland

Glands of the endocrine system that release hormones into the bloodstream -adrenal cortex: releases all steroids such as aldosterone (Na+ reabsorption in kidney) and androgens (puberty) and glucocorticoids (stress response) -adrenal medulla: releases catecholamines such as epinephrine and norepinephrine, mediates stress response and sympathetic nervous system -anterior pituitary gland: releases all peptides, such as growth hormone, prolactin, and ACTH-releasing hormone (supports glucocorticoid secretion by adrenal cortex

Explain the sequence of events and mechanisms occurring at the motor end plate of the neuromuscular junction of vertebrates, including the fate of Ach in the synapse.

NMJ is the connection between a neuron and a muscle cell, most cells only have one neuron, can only be excited 1) voltage gated Ca channels opening causes influx Ca 2+ into the presynaptic cleft 2) Ca 2+ facilitates vesicle fusion to the presynaptic membrane, and acetylcholine is dumped into the synaptic cleft 3) acetylcholine causes Na to rush into the post synaptic cleft and K+ to rush out, depolarizing the membrane 4) action potential moves along the membrane and causes more Na+ channels to open, causing muscle contraction 5) acetylcholine is chopped up by acetylcholinesterase, absorbed into the presynaptic membrane to be turned back into Ach

nicotinic receptors

On all ANS postganglionic neurons, in the adrenal medulla, and at neuromuscular junctions of skeletal muscle, excitatory when bound to Ach, ionotropic receptors permeable to Na+, K+, Ca 2+

agonist

a ligand that binds to the receptor for another molecule and exerts an effect (positive or negative)

antagonist

a ligand that binds to the receptor for another molecule and exerts no effect

synaptic plasticity

ability of synapses to change in strength over time -habituation: decrease in the intensity of a reflex response after repeated exposure to stimuli -sensitization: prolonged enhancement of a reflex response from a stimulus, which results after exposure to a stimuli that is novel or noxious, inactivates K+ channels and activates Ca+ channels

ADH

antidiuretic hormone: released by the posterior pituitary gland, stimulates water retention in the kidneys, vasoconstriction

Nerves

bundled axons that form neural "cables" connecting the central nervous system with muscles, glands, and sense organs

ryanodine receptor

calcium release channel on the SR that connects it to the T-tubule, releases Ca 2+ into the cytosol when Na+ potential allows it to dissociate from DHPR

ganglia

clusters of cell bodies in the PNS

sarcomere

collections of contractile proteins called sarcomeres in striated muscle tissue, fundamental unit of contraction made of actin and myosin proteins -each sarcomere has a z-disk at each end -has 2000 actin filaments attached at their midpoint to the z disk and project to either end -has 1000 myosin filaments at the center of each sarcomere and attached to actin at each end has titin filaments that function as elastic bands

twitch fibers

common muscle fibers that generate contractions through action potentials -fast glycolitic fibers: split 600 ATPs per second, contract quickly, fatigue quickly, white meat -slow oxidative fibers: split 300 ATPs per second, contract slowly, fatigue slowly, red meat (more myoglobin, less LDH, more mitochondria)

CRH

corticotropin-releasing hormone; hypothalamus, peptide releasing hormone that stimulates the release of ACTH from the anterior pituitary gland

Identify and explain the function of the soma, axon, axon hillock, dendrites, and axon terminals within neurons, and distinguish how information travels within neurons from how it travels among neurons.

dendrites recieve signals via neurotransmitters released from sensory neurons, the soma body integrates these signals and generates APs at the trigger zone, AP travels through the axon and is propogated at the nodes of ranvier from the axon hillock to the axon terminals where neurotransmitters are released into the synaptic cleft

catecholamines

dopamine, norepinephrine, epinephrine synthesized from tyrosine -norepinephrine mobilizes energy stores, promotes uptake of glucose into the skeletal muscles, stimulates glycolitic enzymes, and stimulates release of glucocorticoids to replenish energy stores

sarcoplasmic reticulum

endoplasmic reticulum of a muscle cell, network of longitudinal membranes between two t tubules in the sarcolemma, contains ryanodine receptor which connects it to the t tubules

sonic fiber

fastest twitching muscle fibers known, 200 hz per second, faster Ca 2+ release/uptake and muscle contraction/relaxation, has myosin isoforms capable of rapid cross-bridging, troponin with low Ca 2+ binding affinity, increased desnity of Ca 2+ ATPases

mysoin

has 200 myosin heavy chain molecules arranged in helical pairs, has two heads, one with an ATP binding site and another with an actin binding site

neurosecretory tissue

hormone secreting cells stimulated by neural input (adrenal medulla)

hormone

hormones are chemical messengers sent out by neuroendocrine system to exert regulatory control over target cells -steroid hormones: cholesterol derivatives, lipid soluble, secreted by gonads and adrenal cortex, target receptors are intracellular, synthesized as needed not stored (estrogen, testosterone, aldosterone) -peptide hormones: peptide chains, water soluble, secreted by many glands and organs, receptors are extracellular, stored in secretory granules and released through exocytosis (insulin) -amines: tyrosine (catecholamines) and tryptophan (melatonin) derivatives, secreted by a few glands/organs (adrenal medulla, thyroid) (dopamine, epinephrine, norepinephrine)

antagonism

hormones that have opposing effects of other hormones (i.e., glucagon and epinephrine are antagonists of insulin)

synergism

hormones that have the same effect as each other, have greater effect when combined (i.e., glucagon and epinephrine are synergistic to each other)

tropic hormone

hormones that stimulate the release of other hormones, released by anterior pituitary gland to exhibit control of other endocrine cells -ACTH released by anterior pituitary stimulates adrenal cortex to release corticosteroids or glucocorticoids -TSH (thyroid stimulating) stimulates thyroid to release thyroxins -FSH (follice stimulating) stimulates gonads to release estrogens and testosterone -LH (lieutenizing) like FSH

inhibiting hormones

inhibit the release of anterior pituitary hormones

IPSP

inhibitory postsynaptic potential: a slight hyperpolarization of the membrane potential (made more negative) below the voltage threshold, ions involved are K+ and Cl-, neurotransmitters are glycine and GABA

Diagram how muscle length is related to maximum contractile force.

maximal tension that can be generated is dependent upon the length of the muscle during contraction, a medium stretch is where you will get the most contractile force, exists because of maximal overlap of actin-myosin cross bridging

hyperpolarize

membrane potential becomes more negative than resting membrane potential (-65 mV)

depolarize

membrane potential becomes more positive than resting membrane potential (-65 mV)

muscarinic receptors

metabotropic receptors for Ach that activate secondary messenger receptors, they are inhibitory and only located at post-ganglionic synapses of the parasympathetic system in the heart

summation

multiple PSPs can generate an action potential, one is not enough to bring the membrane to the voltage threshold -spatial summation: if a number of PSPs occur simultaneously at different locations on the post-synaptic membrane, the summed PSPs determine if an action potential occurs -temporal summation: if a synapse is activated multiple times at a single location on the post synaptic membrane in a short span of time, the summation of PSPs will result in an overall pronounced PSP - the closer the synapse is to the axon hillock, the stronger the signal produced will be

glucagon

peptide hormone released by pancreatic alpha cells which promotes glucose release from the liver in response to low blood sugar levels, syngergistic with epinephrine and insulin antagonist

insulin

peptide hormone released by pancreatic beta cells which promotes the uptake of nutrients and glucose/glycogen into liver and muscle cells, acts to decrease blood sugar levels, antagonist to glucagon and epinephrine

Synapse

place where to neurons met

tonic fibers

rare fibers which do not generate APs, slower than slowest twitch fibers, found in lower vertebrate postural muscles, very resistant to fatigue

adrenocorticotropic hormone ACTH

released by anterior pituitary gland, promotes adrenal cortex to release glucocorticoids

oxytocin

released by posterior pituitary gland, contracts uterus during birth, lactation, bonding, etc.

glucocorticoids

released by the adrenal cortex, stress response

synaptic vesicle

sacs within the neuron that contain neurotransmitters and released into the synaptic cleft volatage gated ca 2+ channels that allow the vesicle to fuse with the presynaptic membrane, causing exocytosis of the neurotransmitter

endocrine axis

sequence of endocrine control via the anterior pituitary tropic hormones

sarcolemma

sheath over myocytes, forms deep invaginations in the sarcolemma called t tubules

synaptic cleft

small gap between the axon terminals of the presynaptic membrane and the dendrites of the post-synaptic membrane

aldosterone

steroid hormone secreted by adrenal cortex, promotes Na+ reabsorption in the kidney, fluid retention and increases blood pressure

releasing hormones

stimulate release of anterior pituitary hormones

mammalian stress response

suite of physiological responses via the neuroendocrine system geared toward short term survival in threatening situations, HPA axis and sympathetic system work together -sympathetic nervous system responds to nervous system via epinephrine and norepinephrine released by adrenal medulla by increasing heart rate, ventilation, vasconstriction, decreasing digestion and insulin production, increasing glucagon -endocrine system responds to stress via hypothalamus releasing CRH stimulating anterior pituitary gland to release ACTH stimulating adrenal cortex to release glucocorticoids to increase fat catabolism, nutrient metabolism, increasing liver gluconeogenesis -ADH released by posterior pituitary gland (vasopressin) stimulates kidney to retain fluid by concentrating urine -aldosterone released by adrenal cortex stimulates kidney to retain Na+, increasing fluid retention -both cause fluid retention, increasing blood volume and blood pressure during mammalian stress response

Describe the general adaptive value and neuronal mechanisms of three types of synaptic plasticity: (1) habituation, (2) sensitization via presynaptic plasticity, and (3) long-term potentiation, considering the transmitters, potentials, ions, channels and receptors.

synaptic plasticity: ability of a synapse to change its strength over time, known to be important for learning 1) habituation: decrease in intensity of a reflex response due to repeated exposure to a stimulus, EPSP moves the potential less and less toward the voltage threshold, less and less neurotransmitter is released so less ion channels are activated 2) sensitization: prolonged enhancement of a reflex response to a stimulus, which results from a stimulus that is novel or noxious, more neurotransmitter is released after sensitization, K+channels inactivated and Ca 2+ channels activated, interneuron binds to metabotropic seratonin receptor, causing more vesicle fusion 3) simultaenous repition of two stimuli together causes a conditioned reflex response, increases synaptic strength; in normal synaptic transmission, glutamate binds to ionotropic AMPA receptors allowing flux of Na+ and Ca 2+, when an LTP is present, the NDMA receptor allows more Ca 2+ to flux into the cell, more receptors on cell surface of presynaptic cleft, post synaptic cleft will respond to a lower concentration of neurotransmitter

actin

thin filaments, composed of two twisted globular chains of actin molecules, two strands of tropomyosin molecules that lie from end to end on the grooves of the actin chains, and troponin molecules attached at intervals to tropomyosin strands -tropomyosin lies on top of myosin binding sites, myosin cannot bind this way -has tropomyosin binding sites to communicate with it when to move

t tubules

tranverse tubules, invaginations in the sarcolemma with a DHPR which connects it to the sarcoplasmic reticulum

gap junction

two cells bound together through a continuous cytoplasm connected via gap junctions, have protein complexes called connexons that connect two cells intracellularly, allows for electrical transmission (anything that happens in one cell electrically will diffuse into the other)

diabetes mellitus

when the body does not produce or recognize insulin properly -type I: body does not properly produce insulin, usually by autoimmune attack on pancreatic beta cells, strong genetic component -type II: body doesn't recognize insulin, becomes resistant to insulin, strong environmental component due to high sugar diet