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  1. #1
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    54 MCQs on Cardiac Physiology

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



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    Correct Answer: D






    2.

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



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    Correct Answer: B






    3.

    Which of the following would cause the change from curve A to curve B in heart contractility?
    A. Norepinephrine
    B. Acetylcholine
    C. Intracellular acidosis
    D. Ca channel blockers



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    Correct Answer: A







    4.

    Which letter indicates the point in the cardiac cycle that the mitral valve opens?
    A. A
    B. B
    C. C
    D. D
    E. F






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    Correct Answer: D





    5.

    Which letter in the image represents the pressure reaction in the left atrium as the mitral valve bulges during ventricular contraction followed by the stretching of the atrium due to tension of the AV ring?
    A. L
    B. K
    C. F
    D. D



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    Correct Answer: B





    6.

    Which letter in the image represents the isovolumetric contraction of the left ventricle in the heart?
    A. F
    B. B
    C. H
    D. D



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    Correct Answer: A






    7. Which of the following is a CORRECT order of blood flow through the heart?
    1 - right atrium
    2 - left atrium
    3 - right ventricle
    4 - left ventricle
    5 - vena cava
    6 - pulmonary artery
    7 - pulmonary vein
    8 - tricuspid AV valve
    9 - bicuspid (mitral) AV valve
    10 - pulmonary valve
    11 - aortic valve
    12 - aorta

    A. 5, 1, 9, 3, 10, 6, 7, 2, 8, 4, 11, 12
    B. 5, 1, 8, 3, 10, 7, 6, 2, 9, 4, 11, 12
    C. 5, 1, 8, 3, 10, 6, 7, 2, 9, 4, 11, 12
    D. 5, 1, 8, 3, 11, 6, 7, 2, 9, 4, 10, 12



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    Correct Answer: C






    8.

    What type of arrhythmia does this image represent?
    A. First-degree heart block
    B. Third degree heart block (complete AV block)
    C. Premature ventricular contraction
    D. Ventricular fibrillation



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    Correct Answer: C






    9. Which of the following is NOT a part of the specialized conduction system of the heart?
    A. Cells of the SA node.
    B. Cells of the AV node.
    C. Working myocardial cells.
    D. His bundle.
    E. Purkinje fibers.



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    Correct Answer: C






    10. Which of the following is INCORRECT concerning cardiac muscle?
    A. Cardiac cells are smaller than skeletal muscle cells.
    B. Electrical communication between cardiac cells is maintained via gap junctions which are specialized portions of the intercalated discs.
    C. Mechanical attachment of cardiac cells is at the intercalated disc.
    D. The spread of excitation through the heart muscle is 3-dimensional.
    E. Transverse tubules are larger in skeletal muscle than in heart muscle allowing more diffusion of Ca2+ into the interior of the cell.



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    Correct Answer: E






    11. Which of the following is usually the dominant pacemaker and fires the fastest?
    A. SA node.
    B. AV node
    C. His bundle.
    D. Purkinje fibers.



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    Correct Answer: A






    12. Which of the following is NOT true of the parasympathetic control of the heart?
    A. It affects muscarinic receptors.
    B. It decreases heart rate via the SA node.
    C. It decreases conduction velocity via the AV node.
    D. It can be blocked by beta blockers, e.g. propranolol.



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    Correct Answer: D






    13. Which of the following is a TRUE statement concerning pacemaker potential?
    A. Specialized cells depolarize during phase 4, but ventricular and atrial muscle cells do not.
    B. Specialized cells depolarize during phase 3, but ventricular and atrial muscle cells do not.
    C. Specialized cells repolarize during phase 4, but ventricular and atrial muscle cells do not.
    D. Specialized cells repolarize during phase 3, but ventricular and atrial muscle cells do not.
    E. None are correct



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    Correct Answer: A






    14. Which of the following is INCORRECT concerning the voltage clamp technique?
    A. The voltage clamp technique is used to record action potentials from heart cells
    B. It is useful to measure effects of antiarrhythmic agents on specific ion channels.
    C. The voltage clamp can be used to set the Vm either for a segment of the cell membrane or the entire cell.
    D. It allows the investigator to measure both the magnitude and time course of the ionic current generated by ions moving through channels.



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    Correct Answer: A






    15. Which of the following is the property of a cardiac cell to initiate and fire an action potential on its own without external stimulation?
    A. Selectivity
    B. Spontaneity.
    C. Automaticity.
    D. Conductance.



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    Correct Answer: C






    16. Which of the following does NOT show rapid initial depolarization at the start of an action potential?
    A. SA node.
    B. Atrial muscle.
    C. Purkinje fibers.
    D. Ventricular muscle.
    E. Bundle of His.



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    Correct Answer: A






    17. Sodium enters the cell during the upstroke of the action potential. What is the major mechanism for removing Na from the cell?
    A. It passively diffuses out of the cell.
    B. It is extruded via an ATP-dependent Na-K pump.
    C. It is extruded via an ATP-dependent Na-Ca pump.
    D. It is extruded via an ATP-independent Na-K pump.
    E. It is extruded via an ATP-independent Na-Ca pump.



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    Correct Answer: B






    18. If sodium channels are open, membrane potential is +110 mV, and the equilibrium potential is +68 mV, how will sodium ions respond?
    A. They will move into the cell.
    B. They will move out of the cell.
    C. They will not move.
    D. The conductance will drop to zero.



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    Correct Answer: B






    19. Which of the following is NOT true of an inward ionic current?
    A. It is negative.
    B. It reduces the polarity of the cell.
    C. It makes the membrane potential more negative.
    D. It can be caused by Na ions moving into the cell
    E. It can be caused by anions moving out of the cell.



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    Correct Answer: C






    20. If you reduced the outward current in a heart cell, what would be the result?
    A. Increase the rate of repolarization.
    B. Prolong the action potential.
    C. Increase the rate of depolarization.



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    Correct Answer: B






    21. Which of the following is INCORRECT concerning diastolic depolarization at the SA node?
    A. It results from a decrease in IK.
    B. Results from the activation of If carried mainly by Na ions.
    C. Its rate is decreased by sympathetic stimulation.
    D. Activating IKACh decreases its rate.
    E. Its rate is decreased by decreasing ICa



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    Correct Answer: C






    22. If the heart rate increases, which of the following would be a result?
    A. ERP would increase while APD would decrease.
    B. ERP would decrease while APD would increase.
    C. Both ERP and APD would increase.
    D. Both ERP and APD would decrease.



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    Correct Answer: D






    23. Which of the following is INCORRECT concerning local circuit flow in the heart?
    A. It flows from regions with high membrane potential to regions with low potential.
    B. The cell with the more negative potential is called the current source, while the one with the more positive potential is called the current sink.
    C. The circuit flows from the current source to the current sink.
    D. The circuit flows from the active cell to the resting cells in its vicinity.



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    Correct Answer: B






    24. Which of the following is NOT a factor affecting local circuit current in the heart?
    A. Ri
    B. Rmyo
    C. Ro
    D. Cm
    E. Rk



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    Correct Answer: E






    25. 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 extracellular resistance.
    C. Increase in intracellular resistance.
    D. None of the above.



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    Correct Answer: A






    26. Which of the following is FALSE concerning the safety factor in the heart?
    A. It is how much the depolarizing local circuit current exceeds what is required to elicit a propagated action potential.
    B. It depends on the characteristics of the current source and current sink.
    C. It is higher in cells activated by I Na
    D. It is higher in cells activated by I Ca



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    Correct Answer: D






    27. Which of the following would result in an increase in conduction velocity of an impulse through the heart?
    A. Increase Cm
    B. Decrease cell diameter
    C. Increase the threshold voltage (i.e. make it less negative)
    D. Decrease the extracellular resistance.



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    Correct Answer: D






    28. Which of the following will decrease the Vmax and sodium current in a myocardial cell?
    A. A premature heart beat.
    B. Late membrane depolarization.
    C. Low extracellular potassium levels.
    D. More than normal activated Na channels.



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    Correct Answer: A






    29. Which of the following does NOT contribute to the slow conduction found in the SA and AV nodes?
    A. Low AP height.
    B. Small cell size.
    C. High Vmax.
    D. Few nexal connection between cells.



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    Correct Answer: C






    30. Which of the following is INCORRECT concerning gap junctions?
    A. They are composed of junctional channels which have two connexons each.
    B. Connexin protein subunits are arranged around a central pore to compose each connexon.
    C. Gap junctions are more abundant in the atria and ventricles than they are in the SA and AV nodes.
    D. Increases in cytosolic Ca and H will increase gap junction channel conductance.



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    Correct Answer: D






    31. In which of the following do EADs occur more frequently because of their long action potential duration?
    A. Atrial fibers.
    B. SA node
    C. AV node
    D. Purkinje fibers.



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    Correct Answer: D






    32. Which of the following is NOT true concerning the differences between skeletal and cardiac muscle?
    A. The heart has a relatively large T-tubule volume.
    B. The heart has a larger more developed sarcoplasmic reticulum.
    C. The heart relies more on extracellular Ca stores than skeletal muscle.
    D. With limited extracellular Ca, skeletal muscle can contract for close to an hour, while heart muscle can only contract for a few seconds.



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    Correct Answer: B






    33. Which of the following is NOT a method of Ca removal following contraction of heart muscle?
    A. Na-Ca exchange transports Ca out of the cell.
    B. ATP-dependent sarcolemmal Ca pumps remove Ca from the cell.
    C. Ca passively diffuses out of the cell.
    D. ATP-dependent SR Ca pumps move Ca from the cytoplasm into the SR.



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    Correct Answer: C






    34. Which of the following agents helps to increase the Ca storage capacity of the SR in the heart?
    A. dihydropyridines
    B. ryanodine
    C. calsequestrin.
    D. acetylcholine



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    Correct Answer: C






    35. Which of the following is FALSE concerning the regulation of heart muscle performance?
    A. Recruiting more numbers of motor units will increase the strength of contraction.
    B. Increases in end-diastolic volume will generate a larger stroke volume during systole.
    C. The amount and duration of Ca released from the SR can alter contractility.
    D. Positive inotropic agents will increase contractility.



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    Correct Answer: A






    36. Which of the following pairs is INCORRECT?
    A. P wave: atrial depolarization
    B. QRS complex: ventricular depolarization
    C. T wave: ventricular repolarization
    D. QT interval: Measure of duration of atrial action potential



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    Correct Answer: D






    37. Which of the following pairs in INCORRECT concerning the Einthoven triangle?
    A. Lead I: RA/LA
    B. Lead II: RA/LL
    C. Lead III: LA/LL
    D. All of the pairs are correct.



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    Correct Answer: D






    38. Which of the following is NOT affected by the preload in the heart muscle?
    A. End systolic volume
    B. End diastolic volume
    C. Stroke Volume
    D. Ejection fraction.
    E. Cardiac output.



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    Correct Answer: A






    39. Which of the following is INCORRECT concerning isotonic contraction in the heart?
    A. One occurs during the ejection phase of the cardiac cycle.
    B. Is typically the first step in heart muscle contraction followed by an isometric contraction.
    C. It involves a change in muscle length against a constant load.
    D. An increased afterload will slow the velocity of muscle shortening.



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    Correct Answer: B






    40. Which of the following is NOT an effect of a positive inotropic agent on the heart?
    A. It increases stroke volume.
    B. It increases the initial velocity of muscle shortening at all loads.
    C. It increases the rate of blood ejection from the heart.
    D. It decreases the rate of rise in ventricular blood pressure during systole.



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    Correct Answer: D






    41. Which of the following will require the smallest increase in oxygen consumption by the heart?
    A. Generating an increase in left ventricular pressure.
    B. Severe hypertension.
    C. Generating an increase in stroke volume.
    D. Aortic stenosis.



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    Correct Answer: C






    42. Which of the following vessels has the largest effect on total peripheral resistance?
    A. Arteries.
    B. Arterioles.
    C. Veins.
    D. Venules.
    E. Capillaries.



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    Correct Answer: B






    43. If you decrease a blood vessel's radius in half, by what fraction does the blood flow change?
    A. 1/2
    B. 1/4
    C. 1/8
    D. 1/16
    E. 1/32



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    Correct Answer: D






    44. Which of the following is INCORRECT concerning turbulent blood flow?
    A. The resistance to turbulent flow is greater than laminar flow.
    B. Above a critical velocity, blood flow becomes turbulent.
    C. Turbulence can create vibrations that can be detected as murmurs.
    D. Turbulence is found normally in the aorta and in narrowed vessels.
    E. Turbulent flow rate is proportional to the cube root of the driving pressure.



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    Correct Answer: E






    45. Which of the following blood vessels has the greatest compliance?
    A. Arteries.
    B. Veins.
    C. Arterioles.
    D. Capillaries.



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    Correct Answer: B






    46. Which of the following pairs is INCORRECT?
    A. Nitric oxide (NO): vasodilator
    B. Endothelin: vasoconstrictor
    C. Nitric Oxide (NO): promotes cell growth
    D. Endothelin: potent positive inotropic effect



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    Correct Answer: C






    47. Which of the following will NOT increase aortic systolic blood pressure?
    A. Decrease in arterial compliance
    B. Decrease in aortic distensibility.
    C. Increase in stroke volume.
    D. Decrease in ejection velocity.



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    Correct Answer: D






    48. Which of the following is a correct formula for the mean arterial blood pressure?
    A. MAP = CO X SV
    B. MAP = CO X HR
    C. MAP = SV X HR X TPR
    D. MAP = HR X TPR



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    Correct Answer: C






    49. Which of the following pairs is INCORRECT concerning arteriolar tone?
    A. Myogenic control: vascular smooth muscle responds to changes in pressure.
    B. Metabolic control: accumulation of waste products stimulates vasoconstriction.
    C. Neural control: vasoconstriction activated by sympathetic nerves.
    D. Hormonal control: catecholamines affect the adrenergic receptors of the vascular smooth muscle.



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    Correct Answer: B






    50. Which pair is INCORRECT concerning the microcirculation at the capillary level?
    A. Tight junctions: brain
    B. Gaps large enough to exchange plasma proteins: kidneys
    C. Intercellular junctions / pores: exchange of water and lipid-insoluble substances.
    D. Pinocytosis: cytoplasmic vesicles exchanging fluid and solutes.
    E. Intracellular fenestrations: exchange of large molecules.



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    Correct Answer: B






    51. If a patient is suffering from swollen hands, feet, and face, all of the following could be a cause, except?
    A. Large decrease in arterial blood pressure.
    B. Lymphatic blockage.
    C. A decrease in plasma proteins.
    D. Increase in capillary permeability to proteins.
    E. Vasodilation.



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    Correct Answer: A






    52. Which of the following is NOT a mechanism to promote venous return and reduce blood pooling?
    A. One way venous valves.
    B. Parasympathetic stimulation.
    C. Skeletal muscle pump.
    D. Thoraco-abdominal pump
    E. Pumping of the heart.



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    Correct Answer: B






    53. Which of the following in INCORRECT concerning a patient with ventricular tachycardia?
    A. It occurs when the heart rate drops to dangerously low levels.
    B. Cardiac output can falls to dangerous levels.
    C. Arterial blood pressure falls to dangerous levels.
    D. It involves impaired ventricular filling.



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    Correct Answer: A






    54. Which of the following would NOT occur following a major blood loss?
    A. Vagal tone to the SA node would be decreased which would then increase the heart rate.
    B. An increase in sympathetic output in arterioles would increase the total peripheral resistance, except in the brain and heart.
    C. Sympathetic output to the atria and ventricles would increase resulting in an increase in stroke volume.
    D. Sympathetic output to the veins would increase, resulting in increased venous pressure, venous return, and cardiac output.
    E. Stroke volume would increase while heart rate decreased. Together this would increase the cardiac output.



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    Correct Answer: E




    ref: umed.med.utah.edu

  2. #2
    Anonymous is offline Unregistered Guest
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    bump

    bumping for study group

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    Aimen456 is offline Newbie 510 points
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    i cannot view pictures of 54 mcqs on cardiac physiology plz help

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    dgauc is offline Junior Member 510 points
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    Thanks for posting!!

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