What is the contraction of the heart called?

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

Which would be the heart rate of a person if the cardiac output is $5 \; L,$ blood volume in the ventricles at the end of diastole is $100 \; mL$ and at the end of ventricular systole is $50 \; mL?$

$A$: 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?

Which of the following statements regarding the cardiac cycle is incorrect?