Veins

carry blood towards the heart

Veins are blood vessels in our body that carry blood towards the heart. With the exception of the pulmonary veins, they carry deoxygenated blood. Veins differ from arteries amongst other things in structure of the vascular wall: Less muscular and integrated valves are typical characteristics of veins. The valves prevent blood from flowing back in the lower extremities. This is of crucial importance, as the pull effect of the heart on venuous blood is quite low (upstream capillaries intercept blood pressure). For this reason the venous system is also called low-pressure system.