Q. No.| I: | The atria also undergo systole |
| II: | The atrioventricular valves get closed |
| III: | The semilunar valves are forced open |
2. Only I and III are correct
3. Only II and III are correct
4. I, II and III are correct
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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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 |
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
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What is true regarding pulmonic and aortic semilunar valves in the human heart?
1. They prevent the backflow of blood from the ventricles into the atria
2. They are open during the relaxation phase of the ventricles
3. They are held tightly closed by papillary muscles and chordae tendineae
4. They regulate the passage of blood from the ventricles into the pulmonary artery and the aorta
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):
| Assertion (A): | When the ventricles are in systole, the atria are in diastole. |
| Reason (R): | All four chambers of the heart can never be in systole or diastole together. |
In the light of the above statements choose the correct answer from the options given below:
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | Both (A) and (R) are false. |
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.
In a cardiac cycle, both AV valves and the semilunar valves remain closed during
A: Beginning of ventricular systole
B: Beginning of ventricular diastole
| 1. | Only A | 2. | Only B |
| 3. | Both A and B | 4. | Neither A nor B |
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.
What is the average duration of diastole and systole in a cardiac cycle lasting 0.8 seconds?
1. 0.3 seconds; 0.5 seconds
2. 0.4 seconds; 0.4 seconds
3. 0.5 seconds; 0.3 seconds
4. 0.6 seconds; 0.2 seconds
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