Venous System
The venous system is a network of millions of very thin walled vessels that return blood to the heart. The skeletal muscles of the body serve as the pump to push blood back to the heart. Skeletal muscles have to be contracting and relaxing in order for blood to flow through the veins back to the heart.
The venous system is divided into the superficial, perforator, and deep systems. The superficial veins are located above the skeletal muscles and under the skin. The deep veins are located within the skeletal muscles. And the perforator veins connect the superficial veins to the deep veins. Blood travels from the superficial system through the perforators to the deep system and the deep system ends at the heart. Veins start as tiny spider veins in the skin and merge together to form larger and larger veins until the vena cava (largest vein in the body) connects to the heart.
One-way valves located inside the veins prevent blood from flowing backwards in the venous system when the skeletal muscles relax. The valves route blood from the superficial veins, through the perforator veins, and through the deep veins back to the heart. Without the one-way valves, venous blood would not make it back to the heart when you are sitting or standing because gravity would prevent the flow of the blood back to the heart.
Veins have very thin walls and thin muscle in their walls. The venous system acts like a dam or reservoir to hold the blood in reserve until the heart needs to put more blood to the body. When more blood is required to meet the body’s needs, the veins contract and push more blood to the heart. The integrity and elasticity of the vein walls and the one-way valves are, in conjunction with the skeletal muscle pump, critical to the return of blood to the heart and to the health of every organ and tissue in the body.
