12-19-2007, 08:55 PM
Do pulmonary and umbilical veins have valves ???
Most veins have one-way flaps called venous valves that prevent blood from backflowing and pooling in the lower extremities due to the effects of gravity.
In the circulatory system, a vein is a blood vessel that carries blood toward the heart. The majority of veins in the body carry low-oxygen blood from the tissues back to the heart; the exceptions being the pulmonary and umbilical veins which both carry oxygenated blood.
Most veins have one-way flaps called venous valves that prevent blood from backflowing and pooling in the lower extremities due to the effects of gravity.
In the circulatory system, a vein is a blood vessel that carries blood toward the heart. The majority of veins in the body carry low-oxygen blood from the tissues back to the heart; the exceptions being the pulmonary and umbilical veins which both carry oxygenated blood.