The circulatory system is made up of a network of blood vessels. Blood vessels are tube-like channels running throughout the body which include arteries, veins, and capillaries. Arteries bring oxygen-rich blood to all parts of the body. The veins carry blood back to the heart.
Veins carry blood from the extremities to the heart and lungs, where the blood is...
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Three types of veins are found in the legs. The deep veins, enclosed by muscle, lie deep in the legs and carry the most blood to the heart. The superficial veins lie near the surface of the skin. These have the least muscle support and are more likely to become enlarged and twisted. The deep and the superficial veins are connected by the perforator (or communicating) veins.
Since veins carry blood to the heart against the force of gravity, the veins have a system of one-way valves. This helps maintain the flow of blood to the heart. These cup-like valves are spaced at intervals along the inside walls of the vein. The valves open as blood flows toward the heart and close to prevent blood flow back toward the feet.
The valves in the veins usually channel the flow of blood toward the heart.
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The pumping action of the calf muscles against the veins pushes blood upward to the heart. Moving the feet and walking causes the pumping action to occur.
Review Date: 02/05
