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Veins originate in the capillaries and are joining to form increasingly thicker trunks until finally top and bottom are converted into the vena cava, its function is to carry blood from all tissues to the heart from where it will be driven to the lungs so that it is oxygenated and returned again to the general circulation.
There are a group of veins that collected blood from the digestive tract and are joined in a trunk called vena porta which goes straight to the liver, since there the nutrients and substances absorbed during the digestion will be processed for its storage, distribution, or disposal. The liver part of the inferior vena cava that finally comes to the heart.
The veins are usually distributed in pairs, i.e., each artery is accompanied by two veins. Unlike arteries, vein wall lacks a muscular layer so it is less tense and its inside pressure is less, for this reason along its entire course the veins contain structures called valves that have function to prevent blood flowing in the opposite direction. In the interior of veins blood is driven by the contraction of the muscles that surround them to exert an effect of pump, this is especially important in the veins in the legs where gravity favors this retrograde flow.
When the wall of the vein is weak this tends to increase its diameter dilating, what causes that the valves do not close completely to being an I space between them that allows blood to be returned, this phenomenon is known as venous insufficiency.
Varicose veins affect not only the legs, also can be found in other areas of the body such as the testes where are known as varicocele or in the year in which are called hemorrhoids. They can be placed also in the deep venous systems, the pelvis and the vulva of women. In people with cirrhosis of the liver, hardening of the liver affects local circulation and leads to the development of varicose veins in the abdominal venous system, all of them the most important are varicose veins which are located in the esophagus which can break giving origin to a hemorrhage which is usually the cause of death in these patients.
The appearance of varicose veins is related to factors such as sedentary lifestyle, spend much time standing, pregnancy, use of hormonal treatments, the practice of some sports, trauma or thrombophlebitis. This disorder can affect both sexes is more frequent in women and has an important hereditary genetic factor.
Article contributed by the team of collaborators.