Skin

Skin Skin, in anatomy, protective organ covering the external surface of the body and merging, without break, at the various body openings, with the mucous membranes of the alimentary and other canals. The skin forms a protective barrier against the action of physical, chemical, and bacterial agents on the deeper tissues and contains the special end organs for the various sensations commonly grouped as the sense of touch. Through the activity of its sweat glands and blood vessels, it is important in maintaining body temperature. One square inch (6.5 sq cm) of skin contains up to 4.5 m (15 ft) of blood vessels, which have as one of their functions the regulation of body temperature. When the body temperature rises, radiant energy, or heat, is lost due to vascular dilation and increased blood flow to the skin surface. When the temperature is low, blood vessels constrict to reduce blood flow and subsequent heat loss through the skin. Each square inch of skin also contains hundreds of sweat glands that are controlled by a heat regulation center in the brain. These glands secrete moisture, which evaporates, cools the body surface, and helps maintain normal body temperature. In this capacity the skin acts as skin, body, blood, glands, epidermis, vessels, temperature, surface, soles, palms, through, sweat, layer, contains, cells, varies, papillae, one, heat, hair, each, dermis, vascular, various, tissues, square, secrete, regulation, protective, produce, pigment, outer, organ, mm, layers, inch