Latin: vena
German: Vene
Veins are blood vessels that lead the blood circulating in the body back to the heart. Except for the pulmonary veins, they transport blood poor in oxygen, the so-called "venous" blood. The veins are part of the cardiovascular system, and they belong to the so-called low-pressure system, which serves as blood reservoir.
Most veins run parallel to the eponymous arteries, however, there are numerous exceptions, especially among the veins of the skin or the cerebral veins. The advantage of this collocation results from the fact that the expansion of the artery during systole causes a slight compression of the neighboring vein, which further supports the blood flow by the system of venous valves.
Moreover, there are numerous veins that are denominated as eponym according to their discoverer due to their clinical significance, eg.:
The histological structure of the veins greatly differs from the structure of the arteries. The venous wall contains larger quantities of collagenous fibrils alongside smooth muscles and elastic material. This reduces the elasticity of the venous tube. The middle coat is significantly thinner, and the adventitia has no exact delimitation, since its collagen fibers insert into the surroundings.
The structure of the veins also differs depending on their location:
Veins present an ideal access for the parenteral administration of liquids and drugs, or to draw blood for diagnostic purposes. Therefore, the venipuncture belongs to the most important medical techniques.
The superficial veins of the human body are recognizable with the naked eye. The appear as blue protrusions in or above the level of the skin. Under stasis of an extremity they become more pronounced.
Superficial veins seem to be blue because the long-wave red light has a higher depth of penetration into the tissue than the short-wave blue light. Blue light is reflected, red light is absorbed - this makes the veins seem blue until a tissue depth of 1 to 2 millimeters.
The diseases of the veins are the domain of phlebology. Important diseases of the veins include:
This page was last edited on 22 June 2017, at 10:58.
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