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51 |  |  If the SA node is damaged, which part of the heart is most likely to take over as a pacemaker? |
|  | A) | atrial myocardial cells |
|  | B) | AV nodal cells |
|  | C) | Purkinje fibers |
|  | D) | ventricular myocardial cells |
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52 |  |  The normal rate of spontaneous depolarization of the AV node is |
|  | A) | 20 - 40 per minute |
|  | B) | 40 - 60 per minute |
|  | C) | 70 - 80 per minute |
|  | D) | over 100 per minute |
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53 |  |  In which choice are the components of the heart placed in correct order of decreasing intrinsic rhythm? |
|  | A) | SA node, AV node, Purkinje cells |
|  | B) | SA node, Purkinje cells, AV node |
|  | C) | AV node, SA node, Purkinje cells |
|  | D) | Purkinje cells, AV node, SA node |
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54 |  |  The cardiac pacemaker potential is caused by cyclic changes in membrane potential that occur in which of the following sequences? |
|  | A) | slow inflow of Na+ ; rapid K+ inflow; slow K+ outflow |
|  | B) | slow inflow of Ca2+ ; rapid Na+ inflow; rapid K+ outflow |
|  | C) | slow inflow of K+ without Na+ outflow; rapid Na+ inflow; rapid K+ outflow |
|  | D) | slow inflow of Na+ without K+ outflow; rapid Ca2+ inflow; rapid K+ outflow |
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55 |  |  The plateau phase of the cardiac myocardial cell potential |
|  | A) | normally keeps the heart from beating faster than 70 - 80 times per minute |
|  | B) | allows the cell to depolarize spontaneously instead of having to be stimulated by nerve fibers |
|  | C) | prevents tetanus, which would cease pumping action of the heart |
|  | D) | allows the myocardial cells time to rest during the contraction |
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56 |  |  What do skeletal muscle cells, cardiac autorhythmic cells, and cardiac contractile cells have in common? |
|  | A) | In all three, depolarization to threshold is caused primarily by K+ outflow |
|  | B) | In all three, depolarization between threshold and peak membrane potential is caused entirely by Na+ inflow |
|  | C) | In all three, repolarization is caused by K+ outflow |
|  | D) | In all three, the depolarization phase is longer than the repolarization phase |
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57 |  |  If lines were drawn on a typical ECG recording showing where atrial and ventricular systole begin and end, then the ventricular systole would be seen as beginning during a ____ and ending during the next ____. |
|  | A) | P wave; QRS complex |
|  | B) | PR segment; T wave |
|  | C) | QRS complex; T wave |
|  | D) | T wave; P wave |
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71 |  |  The semilunar valves close at the beginning of |
|  | A) | atrial systole |
|  | B) | atrial diastole |
|  | C) | ventricular systole |
|  | D) | ventricular diastole |
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72 |  |  Which part of the cardiac cycle occurs between the time the AV valves close and the semilunar valves open? |
|  | A) | atrial systole |
|  | B) | atrial diastole |
|  | C) | isovolumetric phase of ventricular systole |
|  | D) | ejection phase of ventricular systole |
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73 |  |  The action of acetylcholine after binding to muscarinic receptors on the SA node is to |
|  | A) | open K+ channels, causing hyperpolarization and a decreased rate of spontaneous depolarization |
|  | B) | close K+ channels, causing depolarization and and increased rate of spontaneous depolarization |
|  | C) | open Ca2+ channels, causing increased Ca2+ entry and a stronger contraction |
|  | D) | close Ca2+ channels, causing decreased Ca2+ entry and a faster rate of spontaneous depolarization |
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74 |  |  What is the effect of norepinephrine on the heart? |
|  | A) | It decreases the rate and strength of contraction. |
|  | B) | It increases the rate and strength of contraction. |
|  | C) | It decreases the amount of blood pumped per minute. |
|  | D) | It has no effect on the heart. |
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75 |  |  The amount of blood in the ventricles just before they contract is called the |
|  | A) | end diastolic volume |
|  | B) | end systolic volume |
|  | C) | stroke volume |
|  | D) | cardiac output |
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76 |  |  If the heart rate is 70 beats per minute and stroke volume is 70 ml, then |
|  | A) | ESV is 140 ml |
|  | B) | ESV is 1 ml |
|  | C) | CO = 4900 ml/min |
|  | D) | CO = 140 ml/min |
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77 |  |  The amount of blood ejected from the heart in one minute is called the |
|  | A) | cardiac output |
|  | B) | end diastolic volume |
|  | C) | end systolic volume |
|  | D) | stroke volume |
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78 |  |  Which choice would not increase cardiac output? |
|  | A) | increase heart rate, increase stroke volume |
|  | B) | increase heart rate, no change in stroke volume |
|  | C) | no change in heart rate, increase stroke volume |
|  | D) | decrease heart rate, no change in stroke volume |
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79 |  |  Cardiac output from the left ventricle is |
|  | A) | normally greater than that of the right ventricle |
|  | B) | probably lower than the right ventricle if the person has systemic edema |
|  | C) | probably lower than the right ventricle if the person has pulmonary edema |
|  | D) | probably higher than the right ventricle if the person has pulmonary edema |
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80 |  |  Joe's cardiac output at rest is 5 L/min. When he is exercising strenuously it is 20 L/min. What is Joe's cardiac reserve? |
|  | A) | 4 L/min |
|  | B) | 15 L/min |
|  | C) | 25 L/min |
|  | D) | 100 L/min |
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81 |  |  Based on the information given below, which individual has the greatest tolerance for strenuous exercise? Assume they are similar in terms of size and muscular fitness. |
|  | A) | Ann, cardiac reserve = 8 L/min |
|  | B) | Betsy, cardiac reserve = 15 L/min |
|  | C) | Carla, cardiac reserve = 18 L/min |
|  | D) | Donna, cardiac reserve = 25 L/min |
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82 |  |  Any factor that alters heart rate is called |
|  | A) | a chemotrope |
|  | B) | a chronotrope |
|  | C) | an inotrope |
|  | D) | an isotope |
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83 |  |  Which of the following is not a positive chronotrope? |
|  | A) | acetylcholine |
|  | B) | epinephrine |
|  | C) | thyroid hormone |
|  | D) | caffeine |
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84 |  |  Any factor that causes a change in heart contractility is called |
|  | A) | a chemotrope |
|  | B) | a chronotrope |
|  | C) | an inotrope |
|  | D) | an isotope |
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85 |  |  At a heart rate above 180 beats per minute, all of these decrease except |
|  | A) | cardiac output |
|  | B) | filling time |
|  | C) | stroke volume |
|  | D) | end systolic volume |
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86 |  |  The higher the _____, the greater the cardiac output. |
|  | A) | extracellular K+ concentration |
|  | B) | blood pressure in the aorta |
|  | C) | venous return |
|  | D) | level of acetylcholine released at the SA node |
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87 |  |  With respect to the effect on cardiac output, the term preload refers to |
|  | A) | the force developed by the myocardial cells during ventricular systole |
|  | B) | the blood pressure in the aorta and pulmonary trunk during ventricular systole |
|  | C) | the amount of tension developed in the myocardium before it contracts |
|  | D) | anything that decreases stroke volume |
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88 |  |  Phophodiesterase is the enzyme that degrades cAMP. A drug that inhibits phosphodiesterase would have what effect on the heart? |
|  | A) | It would decrease cardiac contractility by causing increased removal of Ca2+ from the cell. |
|  | B) | It would increase heart rate but have no effect on contractility. |
|  | C) | It would have no effect, because cAMP is not involved in altering cardiac contractility |
|  | D) | It would increase cardiac contractility by prolonging Ca2+ availability inside the cell. |
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89 |  |  Slowing the heart while holding the rate of venous return (ml/min) constant would cause |
|  | A) | decreased cardiac output |
|  | B) | increased cardiac output |
|  | C) | no change in cardiac output, because heart rate is not increased |
|  | D) | no change in cardiac output, because stroke volume is not increased |
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90 |  |  Stroke volume times heart rate equals |
|  | A) | blood pressure |
|  | B) | afterload |
|  | C) | end systolic volume |
|  | D) | cardiac output |
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91 |  |  Which of the following would not increase stroke volume? |
|  | A) | increased venous return |
|  | B) | increased sympathetic stimulation of the myocardium |
|  | C) | increased end diastolic volume |
|  | D) | increased arterial blood pressure |
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92 |  |  The Frank-Starling law of the heart says that the higher the end diastolic volume, the |
|  | A) | lower the cardiac output |
|  | B) | higher the end systolic volume |
|  | C) | lower the blood pressure |
|  | D) | higher the stroke volume |
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93 |  |  In response to exercise, the heart would be called upon to _____ the amount of blood pumped, and this would be initiated by signals from ______ fibers. |
|  | A) | increase; sympathetic |
|  | B) | increase; parasympathetic |
|  | C) | decrease; sympathetic |
|  | D) | decrease; parasympathetic |
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94 |  |  Which of the following would be an effect of cutting the vagus nerve? |
|  | A) | reduced heart rate |
|  | B) | increased heart rate |
|  | C) | reduced strength of contraction |
|  | D) | increased secretion of acetylcholine |
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95 |  |  Inhibition of the SA node by the parasympathetic division of the ANS is called |
|  | A) | cardioacceleration |
|  | B) | inotropia |
|  | C) | bradycardia |
|  | D) | vagal tone |
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96 |  |  In response to an elevation in blood pressure, the cardiac control center would attempt to restore homeostasis primarily through |
|  | A) | sympthetic stimuli to the ventricular myocardium |
|  | B) | sympathetic stimuli to the SA node |
|  | C) | parasympathetic stimuli to the SA node |
|  | D) | parasympathetic stimuli to the ventricular myocardium |
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97 |  |  The ANS is the main extrinsic control for cardiac activity, acting through both sympathetic and parasympathetic fibers innervating the heart. This control system is not symmetric--one part of the ANS has less control over the heart. Which of the following statements is NOT correct? |
|  | A) | The sympathetic division has significant control of heart rate through its action at the SA node. |
|  | B) | The sympathetic division has significant control of contractility through its action on the ventricular myocardium. |
|  | C) | The parasympathetic division has significant control of heart rate through its action at the SA node. |
|  | D) | The parasympathetic division has significant control of contractility through its action on the ventricular myocardium. |
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98 |  |  Which ionic imbalance would decrease the strength of cardiac muscle contraction? |
|  | A) | hypocalcemia |
|  | B) | hypercalcemia |
|  | C) | hypokalemia |
|  | D) | hyponatremia |
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99 |  |  Damage to which of the following parts of the brain would cause the body to have less control over cardiac activity? |
|  | A) | cerebral cortex |
|  | B) | thalamus |
|  | C) | basal nuclei |
|  | D) | medulla oblongata |
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100 |  |  Increased input from the baroreceptors to the cardiac control center would cause which of the following to occur? |
|  | A) | increased sympathetic stimulation and decreased parasympathetic stimulation |
|  | B) | increased sympathetic stimulation and increased parasympathetic stimulation |
|  | C) | decreased sympathetic stimulation and increased parasympathetic stimulation |
|  | D) | decreased sympathetic stimulation and decreased parasympathetic stimulation |
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101 |  |  Which of the following commonly increases with age? |
|  | A) | size of the left ventricle |
|  | B) | size of the right ventricle |
|  | C) | heart rate |
|  | D) | flexibility of heart valves |
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102 |  |  Which of the following commonly decreases with age? |
|  | A) | the size of the left ventricle |
|  | B) | size of the right ventricle |
|  | C) | heart rate |
|  | D) | oxygen consumption by the myocardium |
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