cariac physiology MCQ’s
cariac physiology MCQ’s
1.Which of the following is NOT an inward current? 1.Which of the following is NOT an inward current? A. I Na A. I Na B. I Ca B. I Ca C. I f C. I f D. I Na-K (pump) D. I Na-K (pump)
2. In the image, which curve 2. In the image, which curve represents the IK1?
represents the IK1? A. A A. A B. B B. B C. C C. C D. D D. D E. E E. E
. Which of the following . Which of the following would cause the change from would cause the change from curve ! to curve " in heart curve ! to curve " in heart contractilit#? contractilit#? A. Norepinephrine A. Norepinephrine B. Acetylcholine B. Acetylcholine C. Intracellular acidosis C. Intracellular acidosis D. Ca channel blocers D. Ca channel blocers
!!!.esnips.com"!eb"m#mn
!!!.esnips.com"!eb"m#mn
$. 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
!!!.esnips.com"!eb"m#mn
). Which of the following is a *O++*T order of &lood flow through the heart? ' - riht atrium - left atrium * - riht +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. $irst-deree heart bloc
B. 4hird deree heart bloc (complete A0 bloc) C. 5remature +entricular contraction
D. 0entricular fibrillation
. Which of the following is NOT a part of the speciali/ed conduction s#stem of the heart?
A. Cells of the 6A node. B. Cells of the A0 node. C. 7orin myocardial cells. D. &is bundle.
E. 5urin8e fibers.
10. Which of the following is IN*O++*T concerning cardiac muscle? A. Cardiac cells are smaller than seletal muscle cells.
B. Electrical communication bet!een cardiac cells is maintained +ia ap 8unctions !hich are speciali9ed portions of the intercalated discs.
C. :echanical attachment of cardiac cells is at the intercalated disc. D. 4he spread of e;citation throuh the heart muscle is *-dimensional. E. 4rans+erse tubules are larer in seletal muscle than in heart muscle allo!in more diffusion of Ca< into the interior of the cell.
11. Which of the following is usuall# the dominant pacemaer and fires the fastest?
A. 6A node. B. A0 node C. &is bundle. D. 5urin8e fibers.
12. Which of the following is NOT true of the paras#mpathetic control of the heart?
A. It affects muscarinic receptors.
B. It decreases heart rate +ia the 6A node.
C. It decreases conduction +elocity +ia the A0 node. D. It can be bloced by beta blocers3 e.. propranolol.
1. Which of the following is a T+ statement concerning pacemaer potential?
A. 6peciali9ed cells depolari9e durin phase #3 but +entricular and atrial muscle cells do not.
B. 6peciali9ed cells depolari9e durin phase *3 but +entricular and atrial muscle cells do not.
C. 6peciali9ed cells repolari9e durin phase #3 but +entricular and atrial muscle cells do not.
D. 6peciali9ed cells repolari9e durin phase *3 but +entricular and atrial muscle cells do not.
E. None are correct
1$. Which of the following is IN*O++*T concerning the voltage clamp techni3ue?
A. 4he +oltae clamp techni=ue is used to record action potentials from heart cells
B. It is useful to measure effects of antiarrhythmic aents on specific ion channels.
C. 4he +oltae clamp can be used to set the 0m either for a sement of the cell membrane or the entire cell.
D. It allo!s the in+estiator to measure both the manitude and time course of the ionic current enerated by ions mo+in throuh 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. 5urin8e fibers. D. 0entricular muscle. E. Bundle of &is.
1). 5odium enters the cell during the upstroe of the action
potential. What is the ma6or mechanism for removing Na from the cell?
A. It passi+ely diffuses out of the cell.
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 neati+e.
B. It reduces the polarity of the cell.
C. It maes the membrane potential more neati+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.
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 reions !ith hih membrane potential to reions !ith lo! potential.
B. 4he cell !ith the more neati+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 propaated action potential.
B. It depends on the characteristics of the current source and current sin.
C. It is hiher in cells acti+ated by I Na D. It is hiher 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
C. Increase the threshold +oltae (i.e. mae it less neati+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 heiht. B. 6mall cell si9e. C. &ih 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 arraned 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. 5urin8e fibers.
2. Which of the following is NOT true concerning the differences &etween seletal and cardiac muscle?
A. 4he heart has a relati+ely lare 4-tubule +olume.
B. 4he heart has a larer more de+eloped sarcoplasmic reticulum.
C. 4he heart relies more on e;tracellular Ca stores than seletal muscle. D. 7ith limited e;tracellular Ca3 seletal 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;chane 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 strenth of contraction.
B. Increases in end-diastolic +olume !ill enerate a larer stroe +olume durin systole.
C. 4he amount and duration of Ca released from the 6> can alter contractility.
D. 5ositi+e inotropic aents !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?
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. 6troe 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 chane in muscle lenth aainst 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 stroe +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 stroe +olume. D. Aortic stenosis.
$2. Which of the following vessels has the largest effect on total peripheral resistance?
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
B. Decrease in aortic distensibility. C. Increase in stroe +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. :yoenic control@ +ascular smooth muscle responds to chanes 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 adreneric receptors of the +ascular smooth muscle.
%0. Which pair is IN*O++*T concerning the microcirculation at the capillar# level?
A. 4iht 8unctions@ brain
B. ?aps lare enouh to e;chane plasma proteins@ idneys
C. Intercellular 8unctions " pores@ e;chane of !ater and lipid-insoluble substances.
D. 5inocytosis@ cytoplasmic +esicles e;chanin fluid and solutes. E. Intracellular fenestrations@ e;chane of lare molecules.
%1. If a patient is suffering from swollen hands, feet, and face, all of the following could &e a cause, e4cept?
A. %are decrease in arterial blood pressure. B. %ymphatic blocae.
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.
C. 6eletal 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 danerously lo! le+els. B. Cardiac output can falls to danerous le+els.
C. Arterial blood pressure falls to danerous le+els. D. It in+ol+es impaired +entricular fillin.
%$. Which of the following would NOT occur following a ma6or &lood loss?
A. 0aal 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 stroe +olume.
D. 6ympathetic output to the +eins !ould increase3 resultin in increased +enous pressure3 +enous return3 and cardiac output.
E. 6troe +olume !ould increase !hile heart rate decreased. 4oether this !ould increase the cardiac output.
!nswer 5heet 1 : 10 1 * 2- ! ) : $( * 2 " 11 ! 20 " 2 * - ! $) : ! 12 : 21 * 0 : " $- * $ : 1 ! 22 : 1 : $0 : $ " % " 1$ ! 2 " 2 " $1 * %0 " ( ! 1% * 2$ * $2 " %1 ! ) * 1( ! 2% ! $ * $ : %2 " - * 1) " 2( : % ! $$ % ! * 1- " 2) : ( : $% " %$
