In humans,the duration of a cardiac cycle is ......... seconds.

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

Which of the following stages in the cardiac cycle is of the longest duration $:-$

What is the cardiac output of blood?

$A$: Isovolumetric systole of a normal cardiac cycle is responsible for the opening of semilunar valves causing the blood flow into aortic aorta and pulmonary aorta.
$R$: During isovolumetric systole,intraventricular pressure increases as semilunar and $AV$ valves are closed and ventricles are contracting.

$A$ doctor uses a stethoscope to hear the sounds produced during each cardiac cycle. When is the second heart sound heard?