Question

In man, blood passes from the post caval into the diastolic right atrium of the heart because of

• A. Pushing of venous valves
• B. Suction pull
• C. Beating of SA node
• D. Pressure difference between post caval and atrium

Answer 1

The correct option is D Pressure difference between post caval and atrium

Blood passes from the superior and inferior vana cava into the right atrium. During the start of diastole, the pressure drops in the right atrium, thereby forcing the blood from vena cava to enter the right atrium. During diastole as the atrium relaxes and enlarges in size, the pressure falls.