During systole,what happens in the heart?

How much does the atrial pressure rise during atrial contraction in $mm\,Hg$?

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

The Oxygen-Fick method is used to measure:

Ventricular contraction is preceded by atrial contraction by what duration?

$A$: 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.