Assertion : Atria act as primer pumps that increase the ventricular pumping
Reason : About 80 precent of the blood flows directly through the atria into ventricles.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false

Answer

A

Explanation

Blood normally flows continually from the great veins into the aria , about `80` percent of the blood flows directly through the atria into the ventricles even before the atria contract. Then atrial contraction usually causes an additional `20` percent filling of the ventricles. Therefore, the atria simply function as primer pumps that incerase the vertricular pumping effectiveness as much as `20` percent.