Question

In humans, blood passes from the vena cava to the diastolic right atrium of heart due to

• A. Stimulation of the SA node
• B. Pressure difference between the vena cava and the atrium
• C. Pushing open of the venous valves
• D. Suction pull

Answer 1

The correct option is B Pressure difference between the vena cava and the atrium

B. Pressure difference between the vena cava and the atrium

Reason: Blood passes from the superior and inferior vena cava into the right atrium. During this phase 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 and then the pressure falls.