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

The first heart sound '$Lubb$' occurs in which phase of the cardiac cycle?

The accompanying diagram shows the three stages in the cardiac cycle. Which of the following is the correct sequence?

$A$: 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.

Which one of the following statements is correct?

Define a cardiac cycle and the cardiac output.