Question

Long answer question:

If the duration of the atrial systole is 0.1 sec and that of complete diastole is 0.4 sec, then how does one cardiac cycle complete in 0.8 sec?

Answer 1

1. One cardiac cycle includes atrial systole, ventricular systole, and joint/complete diastole.

2. The duration for atrial systole is 0.1 sec, duration for complete diastole is 0.4 sec, which means if one cardiac cycle completes in 0.8 sec then the duration for ventricular systole is 0.3 sec.

3. Therefore, the duration of one cardiac cycle

= Atrial systole + Ventricular systole + Complete diastole

= 0.1 sec +0.3 sec + 0.4 sec = 0.8 sec

4. Also the relaxation period shortens as the heart beats faster whereas the durations of atrial systole and diastole shortens slightly. Hence, one cardiac cycle completes in 0.8 sec.