毛细血管（Blood capillary）.doc

毛细血管（Blood capillary） Blood capillary Capillary vessels are tiny vessels with small diameter, averaging 6~9 m, and the blood flow is very slow. They are connected between the veins and the arteries and are connected to each other into a mesh. In addition to cartilage, cornea, hair epithelium and enamel, all over the body. The capillary wall is thin and the permeability is large. Its function is to facilitate the exchange of substances between the blood and tissues. Holland Levin microscopist A.van Hooke through a large number of fine observation, interpretation and perfect M. Malpighi concerning capillary system knowledge, that is directly connected to the arteries and veins and capillaries. The blood vessel is a tiny vessel with an average diameter of 6~9 m, connected between the veins and the arteries, and is interconnected into a mesh. A large number of capillaries, in addition to cartilage, cornea, hair epithelium and enamel, all over the body. The capillary wall is thin and has only one layer of epithelial cells. The inner diameter of the tube is very small, the blood flow is slow, the permeability is large, the red blood cells can only pass through one way, and the blood flow velocity in the tube is slower. These characteristics are conducive to the full exchange of substances between the blood and tissues. Holland microscopist A.van Hooke Levin has made many excellent magnification microscopy, the highest was 270 times. He through a lot of subtle observation, interpretation and perfect M. Malpighi concerning capillary system knowledge, proof of arteries and veins and capillaries were directly connected. Capillaries are the most widely distributed, thinnest vessel with the smallest caliber, and only allow 1 red blood cells to pass through. The tube wall is mainly composed of one layer of endothelial cells, and there is a thin layer of connective tissue outside the endothelium. In addition, a flat and protruding cell is often attached to the outer wall of the c