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GMS 6474 Final Exam 2024 Questions
and Answers (GRADED A+)
what does the SR store - ANSWER-proteins and calcium what is the role of the transverse tubules in the muscle fiber - ANSWER-allow inside of muscle to communicate with the outside of the muscle how is a sarcomere measured - ANSWER-from z-disc to z-disc what is contained in the I band of the sarcomere & what color is the band - ANSWER- thin filaments titin z-disc light (isotropic) what is contained in the A band of the sarcomere & what color is the band - ANSWER- thick filaments thin filaments dark (scatters light) what is contained in the H zone & what color is the band - ANSWER-thick filaments light no barbs or myosin middle zone of the sarcomere what is contained in the M line - ANSWER-in the middle of the sarcomere, middle of H zone thick filaments myomesin what does titin do in the sarcomere - ANSWER-structural protein how many zones can you see when the sarcomere is relaxed - ANSWER-all zones can be seen in relaxed state how many zones can be seen when the sarcomere is contracted - ANSWER-sarcomere shortens I band shortens H zone disappears thick and thin filaments overlap DONT shorten
what is the contractile unit of skeletal muscle - ANSWER-the sarcomere what is the main component of the thick filaments - ANSWER-myosin have heavy and light chains motor heads that move it along the thin filament what is the largest protein in the body - ANSWER-titin what are the main components of the thin filaments - ANSWER-actin (where myosin binds) troponin (moves tropomyosin when Ca2+ is present) tropomyosin (covers actin active site) nebulin (sets thin filament length) CapZ (anchors actin to Z-line on z-disc side) Tropomodulin (on end of actin, in middle of sarcomere) alpha-actinin (anchors actin to z-line) what does desmin do in the sarcomere - ANSWER-interacts with alpha-actinin to anchor z-disc to sarcolemma what does dystrophin do in the sarcomere - ANSWER-connects sarcomere to sarcolemma stabilizes the sarcolemma to prevent damage during contractions 1st step of cross-bridge cycle - ANSWER-BINDING activated myosin binds to actin ADP and Pi are still bound to myosin 2nd step of cross bridge cycle - ANSWER-POWER STROKE myosin head swivels movement of actin filament ADP and Pi released from myosin (Pi is released first, before ADP is released) 3rd step of cross bridge cycle - ANSWER-DISSOSCIATION ATP binds to myosin Actin and myosin dissociate (cross bridge detaches) 4th step of cross bridge cycle - ANSWER-ACTIVATION ATP hydrolysis energy activates myosin head ADP and Pi remain bound to myosin if Ca2+ still present, cycle continues how does Ca2+ effect the cross bridge cycle - ANSWER-Ca2+ is needed for the troponin to move the tropomyosin off the actin when Ca2+ runs out, the cross bridge cycle will stop
how many endplates do muscle fibers have - ANSWER-one endplate per muscle fiber anaerobic muscle contraction - ANSWER-short term high levels of ATP fast-twitch muscle fibers energy from metabolism of phosphocreatine and glycogen aerobic muscle contraction - ANSWER-sustainable ATP production slow twitch, oxidative muscle fibers get energy from mitochondria also from glucose, fatty acids, and amino acids type I muscle fibers - ANSWER-slow twitch fatigue resistant oxidative lots of mitochondria no glycogen type IIa muscle fibers - ANSWER-fatigue resistant oxidative more mitochondria than type I abundant glycogen type IIb muscle fibers - ANSWER-fatiguable glycolytic less mitochondria lots of glycogen (relies on anaerobic glycolytic) how to produce more force in motor units - ANSWER-recruit more motor units type I fibers recruited first then type IIa, then IIb what is the henneman size principle - ANSWER-smallest motor units are recruited first then larger motor units as more are recruited, strength of muscle contraction increases orderly addition of sequentially larger and stronger motor units force-velocity relationship - ANSWER-highest force when no change in length so isometric contraction but quickest when muscle is shorter what is the most physiologically relevant marker of performance - ANSWER-power output
power of a contraction is strongest with what kind of load - ANSWER-intermediate velocity is highest when there is what kind of load (tension) - ANSWER-no load or tension but will have no power what shape is the power-load graph - ANSWER-upside down U so no power with lightest or heaviest load what is the equation for power - ANSWER-work/time or force x velocity muscle fiber types are determined by what - ANSWER-motor units is the symmetry in cardiac muscles the same as skeletal muscles - ANSWER-no cardiac muscles have intercalated discs and gap junctions to connect them do cardiac and skeletal muscles have the same sarcomeric structure - ANSWER-yes, striated which kind of muscle has more mitochondria, skeletal or cardiac - ANSWER-cardiac need more ATP to keep heart beating how do the t-tubules in cardiac muscle compare to skeletal muscle - ANSWER-larger t- tubules in cardiac form a dyad instead of triad what controls the action of the cardiac muscle - ANSWER-autonomic nervous system signal triggered by SA node importance of Ca2+ in cardiac muscle - ANSWER-reliant on extracellular Ca2+ more Ca2+ means stronger contraction the DHPR and RyR aren't physically connected like in skeletal muscles so, needs CICR CICR in cardiac muscles - ANSWER-calcium-induced calcium release activated by an action potential Ca2+ signals for RyR to open, not mechanical opening
have intermediate filaments and dense bodies (similar to z-disc) cross bridges shorten 80% (50% more than skeletal muscle) what are caveoli in smooth muscle cells - ANSWER-invaginations in the plasma membrane small stores of Ca2+ contact the SR what is the key signaling molecule in the excitation-contraction phase in smooth muscle
- ANSWER-Ca2+ very similar to cardiac muscle what is one way that Ca2+ is released in smooth muscle that is not seen in cardiac or skeletal muscle - ANSWER-pharmacomechanical coupling w/o action potential using IP3 and store-operated Ca2+ channels what is one element of the sarcomere that smooth muscle is lacking - ANSWER- troponin instead, use myosin light-chain kinase (MLCK) and calmodulin and phosphorylation of light chains changes myosin head shape how does smooth muscle contract - ANSWER-through pharmacomechanical coupling no change in membrane potential use MLCK and myosin phosphatase Ca2+ binds to calmodulin, activates MLCK, phosphorylation changes myosin head shape what are the 2 types of smooth muscle contraction - ANSWER-phasic tonic what is a phasic smooth muscle contraction - ANSWER-contractions in response to single stimuli or brief bursts of stimuli similar to skeletal muscle contractions with Ca2+ and cross-bridge cycling what organs use phasic smooth muscle contractions - ANSWER-in muscles that propel contents of the organ
stomach, intestines what is a tonic smooth muscle contraction - ANSWER-sustained contractions over time no action potentials high Ca2+ levels that fall slowly, but maintain contraction at low Ca2+ levels contraction thru external stimuli what kind of organs use tonic smooth muscle contractions - ANSWER-sphincters and blood vessels how does ATP requirement in smooth muscle compare to the other muscle types - ANSWER-low ATP demand metabolic demand relatively constant length-tension relationship in smooth muscle - ANSWER-if stretched for long periods of time, will adjust to new normal, curve shifts left and right then can go back when shortened again curve looks like upside-down U blood vessels in a series - ANSWER-pulmonary and systemic systems are in series with each other from one side of heart to the other arteries --> capillaries --> veins resistance in series is the resistance of each tube added together blood vessels in parallel - ANSWER-enables independently regulated blood flow to each organ systemic circulation, vascular branches decreases total peripheral resistance total resistance is 1/the resistance of each tube what are the primary resistance vessels - ANSWER-arterioles
what are the main ion channels in cardiac muscle - ANSWER-Ca2+, K+, and Na+ Na+ ion channels in cardiac cells - ANSWER--open at -70 voltage -activates rapidly -Na+ enters cell -depolarizes cell (more + inside) -open during phase 0 of action potential and close during phase 1 K+ ion channels in cardiac cells - ANSWER--flow out of cell -make inside cell more - -4 different kinds -open at + voltages -open during phase 1 of AP what are the 2 types of Ca2+ ion channels in cardiac cells - ANSWER-T-type L-type what are funny currents in the cell - ANSWER--permeable to Na+ and K+ -activated by HYPERPOLARIZATION -@ -60 mV, driving force for Na+ more than K+ -net inward of Na+ T-type Ca2+ ion channels - ANSWER-tiny conductance and transient openings mostly in pacemaker and atrial tissue opens at -55 mV inactivates rapidly small conductance L-type Ca2+ ion channels - ANSWER-large conductance and long lasting openings
in both atria and ventricles important for ventricular function opens at -40 mV inactivates slowly Ca2+ enters cell, depolarizes membrane opens during phase 2 of AP what is the rate of the SA node (normal pacemaker) - ANSWER-60-100 bpm (fastest) what is the rate of the AV node - ANSWER-40-60 bpm what is the rate of the Purkinje system - ANSWER-20-40 bpm which heart segments have the highest conduction velocity - ANSWER-contractile myocardial cells which heart segments have the slowest conduction velocity - ANSWER-SA and AV nodes where is the positive pole of the ECG located in the heart - ANSWER-towards the apex an ECG measures electrical activity of the heart, can it also measure physical activity - ANSWER-no P wave on an EKG - ANSWER--wave of depolarization moving through atria -just before atrial contraction -1st upward deflection on EKG PR segment on EKG - ANSWER--wave of depolarization moving thru AV node, bundle of HIS, and purkinje fibers PR interval - ANSWER--also called AV conduction time -P wave and PR segment -time for depolarization wave to move thru AV node, SA node, bundle of HIS, and purkinje fibers -should be between 0.12-0.20 seconds
there are 20 little boxes between the Rs 20 x 0.04 = 0.80 seconds a beat 60 x 80 = 75 bpm large box method to determine HR on EKG - ANSWER-1 big box between Rs = 300 bpm 2 = 150 bpm 3 = 100 bpm 4 = 75 bpm 5 = 60 bpm 6 = 50 bpm 7 = 43 bpm what is the MEA - ANSWER-mean electrical axis of the heart used during ventricular depolarization found using the radial axis what is the normal MEA - ANSWER-0 to + left axis deviation MEA - ANSWER-0 to - seen in any condition causing left ventricular hypertrophy right axis deviation - ANSWER-+90 to + normal in children and tall, thin adults seen in any condition causing right ventricular hypertrophy Quick and dirty approximation of MEA - ANSWER-use net direction of QRS complexes in lead I and aVF normal MEA: both leads + RAD: lead 1 - & aVF + LAD: lead 1 + & aVF - what is the formula for cardiac output - ANSWER-HR x SV usually around 5 L/minute also EDV-ESV
how does the SNS affect CO - ANSWER-increases contractility increases HR through norepinephrine and increased rate of depolarization easier for AP to excite next cells how does PSNS affect CO - ANSWER-decreases contractility decreases HR does an increased preload or afterload increase the cardiac output - ANSWER-an increased preload will increase CO Frank-Starling law - ANSWER-energy of contraction is proportional to the initial length of the cardiac muscle fiber proportional relationship between EDV and SV does increased contractility increase or decrease stroke volume - ANSWER-increase what is the formula for Ohm's law - ANSWER-delta P = F x R delta P = hydrostatic pressure F = flow (cardiac output) R = resistance (k/(r to the 4th)) k is a constant what is the formula for Poiseuille's law - ANSWER-delta P = F x (kn(l/(r to the 4th))) F = blood flow r = vessel radius n = blood viscosity l = vessel length k = 8/pi what does resistance in a series mean - ANSWER-total resistance is the sum of the resistances along the circuit sum is total of individual resistances examples: systemic (most resistance) and pulmonary systems are in series with each other
how do the left and right sides of the heart pump in fetal circulation - ANSWER-in parallel with each other some blood does not go through all parts of the circulatory system what part of the fetus receives the most blood flow - ANSWER-right atrium ductus venuous - ANSWER-blood from unbilical vein to bypass liver before it enters right atrium does more blood enter the right or left atrium in fetal circulation - ANSWER-right atrium not much blood going thru lungs so not a lot going into left atrium and if any, coming from RA thru foramen ovale what is the pressure in the left ventricle during fetal circulation - ANSWER-65 mm Hg what is the pressure in the right ventricle during fetal circulation - ANSWER-55 mm Hg how do pressures in fetal heart ventricles change as they grow and then on their first day of birth? - ANSWER-both increase why is a baby's first breath so important - ANSWER-their lungs are stiff they need to generate a lottt of pressure to stretch the lungs and take in air next breaths get easier bc of surfactant eventually will have a large change in volume with little changes in pressure like we do is resistance in the pulmonary circulation high or low - ANSWER-low what are passive factors that affect pulmonary vascular resistance - ANSWER-lung volume (increase diameter, decrease resistance) transmural pressure gradient across vessels blood flow and blood pressure gravity zone 1 of the lungs - ANSWER-usually towards apex alveolar pressure is greater than or equal to the pulmonary arterial pressure and greater than the pulmonary venous pressure so no blood flow usually not present under normal conditions, usually if there is hemorrhage
zone 2 of the lungs - ANSWER-pulmonary arterial pressure is greater than the alveolar pressure AND alveolar pressure is greater than the pulmonary venous pressure resistance is increased so flow is reduced normally in apex to middle of lungs zone 3 of the lungs - ANSWER-usually in middle to lower lungs pulmonary arterial pressure is greatest and then pulmonary venous pressure then alveolar pressure most blood flow, vessel completely open greatest gravity effects are the zones of the lungs functional or anatomical - ANSWER-functional what are some active controls to increase pulmonary vascular resistance - ANSWER- oxygen high CO low pH what causes pulmonary edema - ANSWER-excess fluid in the interstitium and lymphatic system that cause fluid to fill the alveoli increased capillary permeability hemodilution what is the baroreflex - ANSWER-most important mechanism for minute to minute control of blood pressure negative feedback loop how is the baroreflex regulated - ANSWER-located in carotid sinus and aortic arch stretch receptors what is the neural pathway - ANSWER-mediate the short term regulation of blood pressure using detectors, afferents, integrator, efferents, and effectors what causes an increase in baroreflex response - ANSWER-increase in blood pressure will eventually signal to decrease blood pressure
vasoconstriction and reduced flow what is the metabolic theory of blood flow - ANSWER-originates from surrounding tissue arterioles are sensitive to local metabolites and outside agents which can cause dilation or constriction what are some metabolites and how do they effect blood flow - ANSWER-adenosine: increase blood flow lactate: increase blood flow H+: increase blood flow K+: increase blood flow what are the 4 Starling Forces - ANSWER--capillary hydrostatic pressure (Pc) -interstitial colloid osmotic pressure (pi I) (pressure exerted by proteins in interstitial space) -interstitial hydrostatic pressure (Pi) -capillary colloid osmotic pressure (pic) (pressure exerted by proteins, primary moving force of water) how do you calculate the net filtration in a cpaillary - ANSWER-net driving pressure = forces out - forces in (Pc + pii) - (Pi + pic) if + number, fluid moving from capillary to interstitial space (called filtration) if - number, fluid moving from interstitial space to capillary (called reabsorption) what would cause a decrease in the reabsorption of fluid into the capillaries - ANSWER- liver failure/kidney disease : less protein production so less capillary osmotic pressure to pull fluid back in lymphatic obstruction: increased Pi so more fluid in interstitial fluid inflammation: increased vessel permeability, increased pii what happens to the blood pressure when you stand up - ANSWER--blood pools in extremities due to gravity and high venous compliance -there is a reduction in venous return, CO, and MAP
-baroreceptor reflex kicks in -increased HR, contractility, and TPR (due to increased SNS and decreased PSNS) -leads to venous return, CO, and MAP returning to normal when laying down, where is most of the pressure located - ANSWER-arteries what is orthostatic hypotension - ANSWER-the inability to restore blood pressure to normal with a change in body position how does the skeletal muscle pump help with pressures while changing positions - ANSWER-muscle contractions force venous blood toward heart venous valves prevent backflow of blood how does the thoracic muscle pump help with pressures while changing positions - ANSWER-"respiratory pumps" changes in intrathoracic pressure when breathing in affect central venous pressure and venous return how does the body react to the increase need for O2 during exercise - ANSWER--blood flow to active muscles increases -active muscles extract more O2 from blood how does the cardiac cycle change during exercise - ANSWER--cardiac period is shortened by 200-400 milliseconds -slow filling phase is shortened or eliminated -SV is increased -ventricular and aortic pressures increase how does cardiac output change during exercise - ANSWER--increase SV from more venous return and more contractility -increase HR from increased SNS and decreased PSNS -vasodilation and decreased TPR (major factor that increases CO) what are the 3 stages of shock - ANSWER--compensated shock
