Semilunar Valves: How They Ensure One-Way Blood Flow in Veins

The flap that opens and closes to allow blood into veins travel in only one direction is called a semilunar valve (also known as a venous valve). These valves are one-way valves that prevent backflow of blood in veins. They are located at regular intervals along the length of the veins, especially in the limbs and organs where there is a risk of pooling or obstruction to blood flow.