Cardiac Physiology MCQs

cardiac physiology MCQ’s

cariac physiology MCQ’s 1.Which of the following is NOT an inward current? A. I Na B. I Ca C. I f D. I Na-K (pump)

2. In the image, which curve represents the IK1? A. A B. B C. C D. D E. E

. Which of the following would cause the change from curve ! to curve " in heart contractilit#? A. Norepinephrine B. Acetylcholine C. Intracellular acidosis D. Ca channel blocers

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$. Which letter indicates the point in the cardiac c#cle that the mitral valve opens? A. A B. B C. C D. D E. $

%. Which letter in the image represents the pressure reaction in the left atrium as the mitral valve &ulges during ventricular contraction followed &# the stretching of the atrium due to tension of the !' ring? A. % B. K C. $ D. D

(. Which letter in the image represents the isovolumetric contraction of the left ventricle in the heart? A. $ B. B C. & D. D


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). Which of the following is a *O++*T order of &lood flow through the heart? ' - riht atrium  - left atrium * - riht +entricle # - left +entricle , - +ena ca+a  - pulmonary artery  - pulmonary +ein / - tricuspid A0 +al+e 1 - bicuspid (mitral) A0 +al+e '2 - pulmonary +al+e '' - aortic +al+e ' - aorta A. ,3 '3 13 *3 '23 3 3 3 /3 #3 ''3 ' B. ,3 '3 /3 *3 '23 3 3 3 13 #3 ''3 ' C. ,3 '3 /3 *3 '23 3 3 3 13 #3 ''3 ' D. ,3 '3 /3 *3 ''3 3 3 3 13 #3 '23 '

-. What t#pe of arrh#thmia does this image represent? A. $irst-deree heart bloc B. 4hird deree heart bloc (complete A0 bloc) C. 5remature +entricular contraction D. 0entricular fibrillation . Which of the following is NOT a part of the speciali/ed conduction s#stem of the heart?



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A. Cells of the 6A node. B. Cells of the A0 node. C. 7orin myocardial cells. D. &is bundle. E. 5urin8e fibers. 10. Which of the following is IN*O++*T concerning cardiac muscle? A. Cardiac cells are smaller than seletal muscle cells. B. Electrical communication bet!een cardiac cells is maintained +ia ap 8unctions !hich are speciali9ed portions of the intercalated discs. C. :echanical attachment of cardiac cells is at the intercalated disc. D. 4he spread of e;citation throuh the heart muscle is *-dimensional. E. 4rans+erse tubules are larer in seletal muscle than in heart muscle allo!in more diffusion of Ca< into the interior of the cell. 11. Which of the following is usuall# the dominant pacemaer and fires the fastest? A. 6A node. B. A0 node C. &is bundle. D. 5urin8e fibers. 12. Which of the following is NOT true of the paras#mpathetic control of the heart? A. It affects muscarinic receptors. B. It decreases heart rate +ia the 6A node. C. It decreases conduction +elocity +ia the A0 node. D. It can be bloced by beta blocers3 e.. propranolol.

1. Which of the following is a T+ statement concerning pacemaer potential? A. 6peciali9ed cells depolari9e durin phase #3 but +entricular and atrial muscle cells do not. B. 6peciali9ed cells depolari9e durin phase *3 but +entricular and atrial muscle cells do not. C. 6peciali9ed cells repolari9e durin phase #3 but +entricular and atrial muscle cells do not. D. 6peciali9ed cells repolari9e durin phase *3 but +entricular and atrial muscle cells do not. E. None are correct



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1$. Which of the following is IN*O++*T concerning the voltage clamp techni3ue? A. 4he +oltae clamp techni=ue is used to record action potentials from heart cells B. It is useful to measure effects of antiarrhythmic aents on specific ion channels. C. 4he +oltae clamp can be used to set the 0m either for a sement of the cell membrane or the entire cell. D. It allo!s the in+estiator to measure both the manitude and time course of the ionic current enerated by ions mo+in throuh channels. 1%. Which of the following is the propert# of a cardiac cell to initiate and fire an action potential on its own without e4ternal stimulation? A. 6electi+ity B. 6pontaneity. C. Automaticity. D. Conductance. 1(. Which of the following does NOT show rapid initial depolari/ation at the start of an action potential? A. 6A node. B. Atrial muscle. C. 5urin8e fibers. D. 0entricular muscle. E. Bundle of &is.

1). 5odium enters the cell during the upstroe of the action potential. What is the ma6or mechanism for removing Na from the cell? A. It passi+ely diffuses out of the cell.



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B. It is e;truded +ia an A45-dependent Na-K pump. C. It is e;truded +ia an A45-dependent Na-Ca pump. D. It is e;truded +ia an A45-independent Na-K pump. E. It is e;truded +ia an A45-independent Na-Ca pump. 1-. If sodium channels are open, mem&rane potential is 7110 m', and the e3uili&rium potential is 7(- m', how will sodium ions respond? A. 4hey !ill mo+e into the cell. B. 4hey !ill mo+e out of the cell. C. 4hey !ill not mo+e. D. 4he conductance !ill drop to 9ero. 1. Which of the following is NOT true of an inward ionic current? A. It is neati+e. B. It reduces the polarity of the cell. C. It maes the membrane potential more neati+e. D. It can be caused by Na ions mo+in into the cell E. It can be caused by anions mo+in out of the cell. 20. If #ou reduced the outward current in a heart cell, what would &e the result? A. Increase the rate of repolari9ation. B. 5rolon the action potential. C. Increase the rate of depolari9ation. 21. Which of the following is IN*O++*T concerning diastolic depolari/ation at the 5! node? A. It results from a decrease in IK. B. >esults from the acti+ation of If carried mainly by Na ions. C. Its rate is decreased by sympathetic stimulation. D. Acti+atin IKACh decreases its rate. E. Its rate is decreased by decreasin ICa 22. If the heart rate increases, which of the following would &e a result? A. E>5 !ould increase !hile A5D !ould decrease. B. E>5 !ould decrease !hile A5D !ould increase. C. Both E>5 and A5D !ould increase.



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D. Both E>5 and A5D !ould decrease. 2. Which of the following is IN*O++*T concerning local circuit flow in the heart? A. It flo!s from reions !ith hih membrane potential to reions !ith lo! potential. B. 4he cell !ith the more neati+e potential is called the current source3 !hile the one !ith the more positi+e potential is called the current sin. C. 4he circuit flo!s from the current source to the current sin. D. 4he circuit flo!s from the acti+e cell to the restin cells in its +icinity. 2$. Which of the following is NOT a factor affecting local circuit current in the heart? A. >i B. >myo C. >o D. Cm E. > 2%. Which of the following will increase the length constant involved in the local circuit current flow of the heart? A. Increase in membrane resistance. B. Increase in e;tracellular resistance. C. Increase in intracellular resistance. D. None of the abo+e. 2(. Which of the following is 8!95 concerning the safet# factor in the heart? A. It is ho! much the depolari9in local circuit current e;ceeds !hat is re=uired to elicit a propaated action potential. B. It depends on the characteristics of the current source and current sin. C. It is hiher in cells acti+ated by I Na D. It is hiher in cells acti+ated by I Ca 2). Which of the following would result in an increase in conduction velocit# of an impulse through the heart? A. Increase Cm B. Decrease cell diameter



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C. Increase the threshold +oltae (i.e. mae it less neati+e) D. Decrease the e;tracellular resistance. 2-. Which of the following will decrease the 'ma4 and sodium current in a m#ocardial cell? A. A premature heart beat. B. %ate membrane depolari9ation. C. %o! e;tracellular potassium le+els. D. :ore than normal acti+ated Na channels. 2. Which of the following does NOT contri&ute to the slow conduction found in the 5! and !' nodes? A. %o! A5 heiht. B. 6mall cell si9e. C. &ih 0ma;. D. $e! ne;al connection bet!een cells. 0. Which of the following is IN*O++*T concerning gap 6unctions? A. 4hey are composed of 8unctional channels !hich ha+e t!o conne;ons each. B. Conne;in protein subunits are arraned around a central pore to compose each conne;on. C. ?ap 8unctions are more abundant in the atria and +entricles than they are in the 6A and A0 nodes. D. Increases in cytosolic Ca and & !ill increase ap 8unction channel conductance. 1. In which of the following do !:s occur more fre3uentl# &ecause of their long action potential duration? A. Atrial fibers. B. 6A node C. A0 node D. 5urin8e fibers. 2. Which of the following is NOT true concerning the differences &etween seletal and cardiac muscle? A. 4he heart has a relati+ely lare 4-tubule +olume. B. 4he heart has a larer more de+eloped sarcoplasmic reticulum.



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C. 4he heart relies more on e;tracellular Ca stores than seletal muscle. D. 7ith limited e;tracellular Ca3 seletal muscle can contract for close to an hour3 !hile heart muscle can only contract for a fe! seconds.

. Which of the following is NOT a method of *a removal following contraction of heart muscle? A. Na-Ca e;chane transports Ca out of the cell. B. A45-dependent sarcolemmal Ca pumps remo+e Ca from the cell. C. Ca passi+ely diffuses out of the cell. D. A45-dependent 6> Ca pumps mo+e Ca from the cytoplasm into the 6>. $. Which of the following agents helps to increase the *a storage capacit# of the 5+ in the heart? A. dihydropyridines B. ryanodine C. calse=uestrin. D. acetylcholine %. Which of the following is 8!95 concerning the regulation of heart muscle performance? A. >ecruitin more numbers of motor units !ill increase the strenth of contraction. B. Increases in end-diastolic +olume !ill enerate a larer stroe +olume durin systole. C. 4he amount and duration of Ca released from the 6> can alter contractility. D. 5ositi+e inotropic aents !ill increase contractility. (. Which of the following pairs is IN*O++*T? A. 5 !a+e@ atrial depolari9ation B. >6 comple;@ +entricular depolari9ation C. 4 !a+e@ +entricular repolari9ation D. 4 inter+al@ :easure of duration of atrial action potential ). Which of the following pairs in IN*O++*T concerning the inthoven triangle?


cardiac physiology MCQ’s A. %ead I@ >A"%A B. %ead II@ >A"%% C. %ead III@ %A"%% D. All of the pairs are correct. -. Which of the following is NOT affected &# the preload in the heart muscle? A. End systolic +olume B. End diastolic +olume C. 6troe 0olume D. E8ection fraction. E. Cardiac output. . Which of the following is IN*O++*T concerning isotonic contraction in the heart? A. ne occurs durin the e8ection phase of the cardiac cycle. B. Is typically the first step in heart muscle contraction follo!ed by an isometric contraction. C. It in+ol+es a chane in muscle lenth aainst a constant load. D. An increased afterload !ill slo! the +elocity of muscle shortenin. $0. Which of the following is NOT an effect of a positive inotropic agent on the heart? A. It increases stroe +olume. B. It increases the initial +elocity of muscle shortenin at all loads. C. It increases the rate of blood e8ection from the heart. D. It decreases the rate of rise in +entricular blood pressure durin systole. $1. Which of the following will re3uire the smallest increase in o4#gen consumption &# the heart? A. ?eneratin an increase in left +entricular pressure. B. 6e+ere hypertension. C. ?eneratin an increase in stroe +olume. D. Aortic stenosis. $2. Which of the following vessels has the largest effect on total peripheral resistance?


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A. Arteries. B. Arterioles. C. 0eins. D. 0enules. E. Capillaries. $. If #ou decrease a &lood vessel;s radius in half, &# what fraction does the &lood flow change? A. '" B. '"# C. '"/ D. '"' E. '"*

$$. Which of the following is IN*O++*T concerning tur&ulent &lood flow? A. 4he resistance to turbulent flo! is reater than laminar flo!. B. Abo+e a critical +elocity3 blood flo! becomes turbulent. C. 4urbulence can create +ibrations that can be detected as murmurs. D. 4urbulence is found normally in the aorta and in narro!ed +essels. E. 4urbulent flo! rate is proportional to the cube root of the dri+in pressure. $%. Which of the following &lood vessels has the greatest compliance? A. Arteries. B. 0eins. C. Arterioles. D. Capillaries. $(. Which of the following pairs is IN*O++*T? A. Nitric o;ide (N)@ +asodilator B. Endothelin@ +asoconstrictor C. Nitric ;ide (N)@ promotes cell ro!th D. Endothelin@ potent positi+e inotropic effect $). Which of the following will NOT increase aortic s#stolic &lood pressure? A. Decrease in arterial compliance



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B. Decrease in aortic distensibility. C. Increase in stroe +olume. D. Decrease in e8ection +elocity. $-. Which of the following is a correct formula for the mean arterial &lood pressure? A. :A5  C  60 B. :A5  C  &> C. :A5  60  &>  45> D. :A5  &>  45> $. Which of the following pairs is IN*O++*T concerning arteriolar tone? A. :yoenic control@ +ascular smooth muscle responds to chanes in pressure. B. :etabolic control@ accumulation of !aste products stimulates +asoconstriction. C. Neural control@ +asoconstriction acti+ated by sympathetic ner+es. D. &ormonal control@ catecholamines affect the adreneric receptors of the +ascular smooth muscle. %0. Which pair is IN*O++*T concerning the microcirculation at the capillar# level? A. 4iht 8unctions@ brain B. ?aps lare enouh to e;chane plasma proteins@ idneys C. Intercellular 8unctions " pores@ e;chane of !ater and lipid-insoluble substances. D. 5inocytosis@ cytoplasmic +esicles e;chanin fluid and solutes. E. Intracellular fenestrations@ e;chane of lare molecules. %1. If a patient is suffering from swollen hands, feet, and face, all of the following could &e a cause, e4cept? A. %are decrease in arterial blood pressure. B. %ymphatic blocae. C. A decrease in plasma proteins. D. Increase in capillary permeability to proteins. E. 0asodilation. %2. Which of the following is NOT a mechanism to promote venous return and reduce &lood pooling? A. ne !ay +enous +al+es. B. 5arasympathetic stimulation.


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C. 6eletal muscle pump. D. 4horaco-abdominal pump E. 5umpin of the heart. %. Which of the following in IN*O++*T concerning a patient with ventricular tach#cardia? A. It occurs !hen the heart rate drops to danerously lo! le+els. B. Cardiac output can falls to danerous le+els. C. Arterial blood pressure falls to danerous le+els. D. It in+ol+es impaired +entricular fillin. %$. Which of the following would NOT occur following a ma6or &lood loss? A. 0aal tone to the 6A node !ould be decreased !hich !ould then increase the heart rate. B. An increase in sympathetic output in arterioles !ould increase the total peripheral resistance3 e;cept in the brain and heart. C. 6ympathetic output to the atria and +entricles !ould increase resultin in an increase in stroe +olume. D. 6ympathetic output to the +eins !ould increase3 resultin in increased +enous pressure3 +enous return3 and cardiac output. E. 6troe +olume !ould increase !hile heart rate decreased. 4oether this !ould increase the cardiac output.

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Cardiac Physiology MCQs

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