Question

What are the factors that reinforce the blood to return back toward the heart (so no need for valves to be between veins and atrium)?

Answer 1

Factors responsible for blood return back to heart. ::

1) sympthetic stimulation - It decreses the compliance of the venous system and hence Increases the blood return to heart indirectly by Increasing cardiac output.

2) Respiratory - during inspiration there is negative pressure inside the thorax, this negative pressure is transmitted to vena cava and hence this Increases venous return during inspiration.

3) Muscular contraction - Rhythmic contraction of the muscle of limbs during daily activities Increases venous retrun.

4) Peripheral heart - Calf muscle and deep venous system form peripheral heart help in pushing the blood towards heart against gravity.