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White veins in dark rock at Imperia, Italy. In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved is usually due to hydrothermal circulation. [1]
Veins become more visually prominent when lifting heavy weight, especially after a period of proper strength training. Physiologically, the superficial veins are not as important as the deep veins (as they carry less blood) and are sometimes removed in a procedure called vein stripping, which is used to treat varicose veins.
Deep veins are deeper in the body and have corresponding arteries. Perforator veins drain from the superficial to the deep veins. [16] These are usually referred to in the lower limbs and feet. [17] Superficial veins include the very small spider veins of between 0.5 and 1 mm diameter, and reticular or feeder veins. [18] Venous plexuses
Though veins might make it appear as such, human blood is never naturally blue. [3] The blue appearance of surface veins is caused mostly by the scattering of blue light away from the outside of venous tissue if the vein is at 0.5 mm deep or more. Veins and arteries appear similar when skin is removed and are seen directly. [4] [5]
Veins have a much higher compliance than arteries (largely due to their thinner walls.) Veins which are abnormally compliant can be associated with edema. Pressure stockings are sometimes used to externally reduce compliance, and thus keep blood from pooling in the legs.
The term "hepatojugular reflux" was previously used as it was thought that compression of the liver resulted in "reflux" of blood out of the hepatic sinusoids into the inferior vena cava, thereby elevating right atrial pressure and visualized as jugular venous distention. The exact physiologic mechanism of jugular venous distention with a ...
Angelina Jolie stopped to greet a fan with a rare bone disorder during a red carpet for the movie "Maria" in Venice Thursday.
Varicose veins are unlikely to be caused by crossing the legs or ankles. [17] Less commonly, but not exceptionally, varicose veins can be due to other causes, such as post-phlebitic obstruction or incontinence, venous and arteriovenous malformations. [18] Venous reflux is a significant cause. Research has also shown the importance of pelvic ...