Question

The valve which prevents the back flow of blood in veins and lymph vessels.

Answer 1

bicuspid valve....i think

Answer 2

When the muscles contract the blood within the veins is squeezed up the vein and the valves open. When the muscle is at rest, the valves close helping to prevent the backward flow of blood. ... Veins have valves that keep blood moving in one direction: back toward the heart.