|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
71 | | The semilunar valves close at the beginning of |
| | A) | atrial systole |
| | B) | atrial diastole |
| | C) | ventricular systole |
| | D) | ventricular diastole |
|
|
|
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 |
|
|
|
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 |
|
|
|
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. |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
82 | | Any factor that alters heart rate is called |
| | A) | a chemotrope |
| | B) | a chronotrope |
| | C) | an inotrope |
| | D) | an isotope |
|
|
|
83 | | Which of the following is not a positive chronotrope? |
| | A) | acetylcholine |
| | B) | epinephrine |
| | C) | thyroid hormone |
| | D) | caffeine |
|
|
|
84 | | Any factor that causes a change in heart contractility is called |
| | A) | a chemotrope |
| | B) | a chronotrope |
| | C) | an inotrope |
| | D) | an isotope |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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. |
|
|
|
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 |
|
|
|
90 | | Stroke volume times heart rate equals |
| | A) | blood pressure |
| | B) | afterload |
| | C) | end systolic volume |
| | D) | cardiac output |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
95 | | Inhibition of the SA node by the parasympathetic division of the ANS is called |
| | A) | cardioacceleration |
| | B) | inotropia |
| | C) | bradycardia |
| | D) | vagal tone |
|
|
|
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 |
|
|
|
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. |
|
|
|
98 | | Which ionic imbalance would decrease the strength of cardiac muscle contraction? |
| | A) | hypocalcemia |
| | B) | hypercalcemia |
| | C) | hypokalemia |
| | D) | hyponatremia |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|
|
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 |
|
|