Q. No.Which of the following causes the second heart sound [dub]?
1. opening of the AV valves at the start of diastole
2. closing of the AV valves at the start of systole
3. opening of the semilunar valves at the start of systole
4. closing of the semilunar valves at the start of diastole
1. opening of the AV valves at the start of diastole
2. closing of the AV valves at the start of systole
3. opening of the semilunar valves at the start of systole
4. closing of the semilunar valves at the start of diastole
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Tissue death (necrosis) due to inadequate blood supply to the affected area, such as the heart, is:
| 1. coronary thrombosis | 2. angina pectoris |
| 3. ischemia | 4. infarction |
The deficiency of cynocobalamin or vitamin B12 causes:
| 1. aplastic anemia | 2. pernicious anemia |
| 3. hemolytic anemia | 4. hemorrhagic anemia |
The volume of blood being pumped by the heart, in particular by the left or right ventricle, per unit time is called as:
| 1. stroke volume | 2. end-diastolic volume |
| 3. ejection fraction | 4. cardiac output |
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Capillary walls are different from the walls of veins and arteries as they are composed of:
1. endothelium only.
2. endothelium and smooth muscle.
3. a tunica interna and a tunica media.
4. smooth muscle and elastic connective tissue.
Electrical relay station, slowing the electrical current sent by the sinoatrial (SA) node before the signal is permitted to pass down through to the ventricles, is/are:
| 1. bundle branches | 2. Purkinje fibers |
| 3. AV node | 4. AV bundle |
The period of the cardiac cycle where the greatest amount of ventricular filling occurs is:
1. the first one-third of diastole.
2. the middle one-third of diastole.
3. the last one-third of diastole.
4. ventricular systole.
What is most likely to happen if the SA node suddenly stops generating the impulse?
1. The heart will stop.
2. The ventricles will contract, but the atria will stop.
3. Another part of the heart, possibly the AV node, will become the pacemaker.
4. The atria will keep contracting, but the ventricles will stop.
Pericardial fluid is the serous fluid secreted by the serous layer of the pericardium into the pericardial cavity and it serves to:
1. reduce friction between the pericardial membranes.
2. lubricate the heart valves.
3. replace any blood that is lost.
4. provide oxygen and nutrients to the endocardium.
The SA node is the normal pacemaker of the human heart because its cells
1. spontaneously generate electrical signals about 70 to 80 times per minute.
2. are located in the interventricular septum.
3. generate electrical signals only when stimulated by sympathetic fibers.
4. are not in contact with other cells of the heart.
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