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A blood vessel that transports blood from the capillaries back to the heart.
Blockages of blood vessels prevent the flow of oxygen to the tissues. These can damage or destroy the affected organ(s). A blockage in the coronary artery will damage the heart and could result in death.
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from the capillaries back toward the heart . Blood vessels do not actively engage in the transport of blood (they have no appreciable peristalsis), but arteries—and veins to a degree—can regulate their inner diameter by contraction of the muscular layer. This changes the blood flow to downstream organs, and is determined by the autonomicnervous system. Vasodilation and vasoconstriction are also used antagonistically as methods of thermoregulation.
As part of the circulatory system, the blood vessels aid in gas exchange. Oxygen (bound to hemoglobin in red blood cells) is the most critical nutrient carried by the blood. In all arteries, apart from the pulmonary artery, hemoglobin is highly saturated (95-100%) with oxygen. In all veins, apart from the pulmonary vein, the hemoglobin is desaturated at about 75%, but veins carry carbon dioxide, which will eventually be expelled from the lungs. (The values are reversed in the pulmonary circulation. )
While blood vessels have no appreciable peristalsis, arteries (and veins, to a degree) can regulate their inner diameter by contraction of the muscular layer. This changes the blood flow to downstream organs, which is determined by the autonomic nervous system. Vasodilation and vasoconstriction are also used antagonistically as methods of thermoregulation. The endothelium is permeable so that nutrients carried in the blood can be released to the tissues.