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16. Which of the following is not a feature of SA node?
A. SA node has autorhythm. B. SA node determines heart rate. C. SA node has
stable resting potential.
D. SA node is localized in right atrium.
E. SA node is
localized near superior vena cava.
17. If the ECG exhibits a regular interval between adjacent normal P waves but the heart
beats irregularly,
A. the SA node is not functioning normally. B. the signals from SA node may be
blocked at AV node. C. the atria do not contract regularly.
D. the AV valves can
close only partially. E. the AV valves can open only partially.
18. The average resting cardiac cycle takes about 0.8 sec, including ___.
A. 0.5 sec for ventricular systole and 0.3 sec for ventricular diastole.
B. 0.6 sec for
ventricular systole and 0.2 sec for ventricular diastole.
C. 0.4 sec for ventricular
systole and 0.4 sec for ventricular diastole.
D. 0.3 sec for ventricular systole and 0.5 sec for ventricular diastole.
E. 0.7 sec for
ventricular systole and 0.1 sec for ventricular diastole.
19. Which of the following is the right sequence of phases in a cardiac cycle?
A. atrial contraction, ventricular filling, isovolumic ventricular relaxation, ventricular ejection, isovolumic
ventricular contraction
B. ventricular filling, atrial contraction, isovolumic ventricular relaxation, ventricular ejection, isovolumic
ventricular contraction
C. ventricular filling, atrial contraction, isovolumic ventricular contraction, , ventricular ejection
isovolumic ventricular relaxation
D. atrial contraction, ventricular filling, isovolumic ventricular contraction, ventricular
ejection, isovolumic ventricular relaxation
E. isovolumic ventricular relaxation, atrial contraction, ventricular filling, isovolumic
ventricular contraction, ventricular ejection
20. A heart rate of 45 beat/min (bpm) and the absence of P waves from the
electrocardiogram would suggest ___.
A. ventricular fibrillation.
B. ventricular flutter. C. a bundle branch block.
D. aortic stenosis.
E. damage to the SA node.
21. The amount of blood (ml) ejected by one ventricle in one heartbeat is called ___.
A. the ejection fraction.
B. the preload.
C. the afterload.
D. the
stroke volume.
E. the cardiac output.
22. Atrial systole begins ___.
A. immediately before the P wave.
B. immediately after the P wave.
during the Q wave.
D. during the S-T segment. E. immediately after the T wave.
23. The cardiac center, which modifies the heart rate, is located in ___.
C.
A. the hypothalamus. B. the cerebral cortex C. the carotid sinuses.
arch.
E. the medulla oblongata.
D. the aortic
24. The cardioinhibitory center communicates with the heart by way of ___.
A. the ventricular muscles. B. parasympathetic nerves. C. the bundle of His.
D. the Purkinje fibers.
E. sympathetic nerves.
25. At the end of ventricular contraction, the amount of blood remaining in the ventricle
is ___.
A. the end-diastolic volume. B. the end-systolic volume. C. the stroke volume.
D. the residual volume.
E. the ejection fraction.
26. The heart’s normal ___ of 54% can rise to as high as 70% during exercise.
A. end-diastolic volume.
B. end-systolic volume.
C. ejection fraction. D.
residual volume.
E. stroke volume.
27. Pressure in the arteries that opposes the opening of the semilunar valves is called
___.
A. ejection pressure. B. venous return.
C. afterload. D. preload. E. stroke
volume.
28. The second heart sound immediately follows ___.
A. closing of the AV valves. B. the end of diastole. C. the P wave. D. the QRS
complex.
E. closing of the aortic and pulmonary valves.
29. The conduction of electrical signals is fastest in ___.
A. the atria. B. the regular ventricular muscle cells. C. the Purkinje fibers.
D. the SA node. E. the AV node.
30. One way of stating the Frank-Starling law of the heart is that stroke volume is
proportional to ___.
A. the end-systolic volume. B. the end-diastolic volume. C. the afterload.
D. the heart rate. E. contractility.
31. Baroreceptors are located in ___.
A. the aorta and carotid sinuses. B. the superior and inferior venae cavae. C. the
pulmonary arteries.
D. the internal and external jugular veins. E. the ventricles.
32. Given the stroke volume of 80 ml, end-diastolic volume of 160 ml, and a cardiac
output of 6.4 L/min, the heart rate is ___.
A. 20 bpm. B. 40 bpm. C. 60 bpm. D. 80 bpm. E. 100 bpm.
33. During isovolumetric contraction, the pressure in the ventricles ___.
A. rises rapidly.
B. falls rapidly.
C. remains constant.
D. rises and then
falls.
E. falls and then rises.
34. Hypercapnia (high CO2 in the blood) has the effect of ___.
A. increasing the heart rate. B. decreasing the heart rate. C. decreasing myocardial
contractility.
D. increasing refractory period. E. reducing the ejection fraction.
35. The effect of vagal tone on the heart is to ___.
A. decrease ventricular contractility. B. decrease stroke volume.
rate.
D. decrease P-R interval.
E. decrease R-R interval.
36. The heart rate is increased by ___.
A. hypothyroidism. B. acetylcholine.
hypernatremia.
E. hypercalcemia.
C. hyperkalemia.
C. decrease heart
D.
37 An anatomical arrangement that reduces the risk for myocardial infarctions is ___.
arterial anastomoses in the coronary circulation.
the desmosomes of the intercalated
discs.
continuous blood flow.
gap junctions in the myocardium.
circumflex arteries.
38. A substance that reduces the heart rate is said to exert ___.
a positive inotropic effect.
a negative chronotropic effect.
barotropic effect.
a negative inotropic effect.
a positive chemotropic effect.
a positive
39. Which of the following decreases the heart rate?
Epinephrine acetylcholine norepinephrine
thyroid hormone
nicotine
40. Because the human heart has autorhythm, ___.
it will beat even if all nerves to it are severed.
both ventricles pump the same
amount of blood.
it is not subject to the influence of hormones.
it is not subject to the influence of
nerves.
it is more vulnerable to the lack of blood supply.
41. Which of the following phases occurs right after ventricular ejection?
A. atrial contraction. B. ventricular filling. C. isovolumic ventricular contraction.
D. isovolumic ventricular relaxation.
42. Can both tricuspid and pulmonary semilunar valves stay open simultaneously at any
time in a cardiac cycle of a normal person?
A. yes. B. no.
43. The QRS complex corresponds to ___.
A. ventricular repolarization. B. ventricular depolarization. C. atrial depolarization.
44. A patient's ECG displays 70 P waves but only 60 QRS complexes every minute, he
likely has a ___.
A. first degree AV block.
B. second degree AV block. C. third degree AV block..
45. If the end diastolic ventricular volume is 130 ml, the end systolic (after ejection)
ventricular volume is 60 ml and the heart rate is 70 beat/min, the cardiac output will be
___.
A. 130 ml. B. 70 ml. C. 60 ml. D. 4,200 ml/min. E. 4,900 ml/min.
46. The Frank-Starling Law states that ___.
A. an increase in the afterload will increase cardiac output.
B. an increase in
contractility will increase cardiac output. C. an increase in the preload will increase
cardiac output. D. a decrease in the afterload will increase cardiac output.
47. If a healthy man increases his heart rate from 200/min to 250/min, his cardiac output
will most likely ___.
A. increase. B. decrease. C. remain unchanged.
48. When blood pressure increases suddenly, the baroreceptor reflex is expected to
mediate ____.
A. a negative inotropic effect.
B. a positive inotropic effect. C. a positive
chronotropic effect
KEY
16C 17B 18D 19C 20E 21D 22B 23E 24B 25B 26C 27C 28E 29C 30B
31A 32D 33A 34A 35C 36E 37A 38B 39B 40A
41D
42B 43B 44B
45E 46C 47B 48A