How come blood doesn't pool in our legs when we are walking upright?

Question

we notice changes from changing from supine to upright; how come our blood doesn't pool in our legs when we walk upright?

Answer 1

Blood in the human body is in a closed circulatory system that is under constant pressure do to the pumping mechanism of the heart.  While it is true that there are valves that ensure that the blood only flows one way, it is the heart that maintains the pressure required to keep this system intact.  Also when we are walking, standing or exerting any amount of energy we increase that circulation which in turn raises the pressure of the system.

Answer 2

because we have valves in our veins to prevent the back-flowing of blood.

(varicose veins are caused by damaged valves, hence the thick noticeable veins on people who suffer from this.)

Answer 3

The heart is a pump which keeps the blood circulating throughout the body. The only time that blood pools is when a person dies. The blood will settle into the lowest parts of the body and these areas will assume a bright red color. The condition is called post mortum lividity.

Answer 4

Because our veins in our legs pump blood upwards. Plus they have tiny valves, which prevent blood flowing downwards.