if a heartbeat pushes blood to an organ with that beat’s force, then after it reaches capillaries, how would the deoxygenated blood return to the heart? With the momentum reduced at capillaries or organs, which force drives the blood back to the heart?
In: Biology
The exact same force that pushes it to the organs. Assuming you’re not bleeding heavily, it’s a closed system. As oxygenated blood is “pushed” into the organ, through the arteries, the deoxygenated blood is pushed out, through the veins to be reoxygenated
The larger veins, particularly in the legs, also have one-way valves in them that prevent backflow. So in a healthy system, the veins only flow back to the heart.
Incidentally, spider and varicose veins are caused by failures in those valves which allows blood to pool in those areas.
Generally the muscles surrounding the veins along with some of the pressure that is sending the blood to the organs maintains the pressure required for the venous blood to flow.
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