Question

◦ How does blood return to the heart through veins even though the pressure in veins is very low?

Answer 1

ANSWER:

The vein carry the deoxygenated blood into the heart. There two large vein called superior vein cava and inferior vena cava.
The superior vena cava carries the deoxygenated blood from the upper part of the body from the shoulder, arms,neck and head.
And the inferior vena Cava carries the deoxygenated blood from the lower part of the body. Like from the abominal region, hip and from the legs.

Vein have low pressure when compare to the arteries. Because veins are made up of thin walls of the muscles when compare to the arteries. So there will be a low pressure in the veins.

But we can see that the veins are the one which getting the blood from the body and send it the heart. It is because the vein have specialised structure called one way valve.
It is not presented in the arteries but mainly presented in the veins of the human body.

The function of the one way valve is to prevent the back flow of the blood. One the aim is to achieve the heart so ones it goes towards the heart it can able to get back (back flow).

Diagram A - This shows when the valve is in open stage. In that time the blood will be get back to the heart.
Diagram B- This shows the closing of the valve, so the blood will not goes in the opposite direction of the heart.