Question

Atrial systole lasts for .......... in cardiac cycle.

• A. $0.1$ second
• B. $0.3$ second
• C. $0.5$ second
• D. $0.7$ second

Answer 1

Answer: (A)

$0.1$ second

A cardiac cycle is made up of atrial systole and diastole and ventricular systole and diastole. In humans, the heart beats for about 72 times per minute. Hence the time of a cardiac cycle is 60/72=0.860/72=0.8 sec approx. The total time of one cardiac cycle is distributed into atrial systole 0.8 sec. Atrial diastole 0.1 sec, ventricular systole 0.3 seconds and complete cardiac diastole 0.4 seconds. Thus the correct answer is option A.