The dermis is a single thick layer composed of

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The dermis is a single thick layer composed of connective tissue, which gives the skin its elastic qualities. struc- tures within the skin that produce an oily secretion called sebum , are also found in the dermis. Sebum helps keep skin and hair from drying out. Blood vessels in the dermis supply cells with oxygenated blood and nutrients and facilitate the removal of cellular wastes. These blood vessels also function in temperature regulation. When body temperature begins to rise, the blood vessels in the skin dilate. This allows heat to escape through the skin’s surface. If body tempera- ture begins to drop, the blood vessels in the skin constrict, decreas- ing the amount of blood and heat loss at the skin’s surface. structures within the dermis that secrete perspiration through glands Sweat Sebaceous glands melanin
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362 Chapter 14 Personal Care and Healthy Behaviors ducts to pores on the skin’s surface , also are involved in temperature regulation. Sweat glands produce perspiration on the surface of the skin. Body heat is lost as the sweat evaporates. Touch a hot stove, and your hand immediately pulls back. Why? The skin is a major sense organ. Nerve cells in the dermis act as receptors, which are stimulated by changes in the outside environ- ment. These receptors enable you to feel sensa- tions such as pressure, pain, hot, and cold. Healthy Skin eeping your skin healthy should be an K important part of your daily routine. Wash your face every morning and evening with mild soap and water. Daily washing, bathing, or showering helps remove and slow the growth of bacteria that cause body odor. Avoid touching your face with your hands. This can introduce new bacteria to the skin’s surface. Carefully choose personal skin care products, such as moisturizers, shaving cream, or cosmetics, to help keep your skin from becoming irritated or having an allergic reaction. Follow a well-balanced diet that is rich in vitamins and minerals. Foods such as milk, green and yellow vegetables, and liver are rich in vitamin A—a vitamin that is particularly important for healthy skin. Skin and the Sun Understanding the effects of UV radiation on the skin and know- ing some preventive behaviors can help you protect your skin now and throughout your life. When skin is exposed to UV rays, whether from the sun, a tanning booth, or another source, melanin production is increased. This self-protective mechanism is the skin’s attempt to protect its cells from UV rays. Fair-skinned people whose skin has little melanin, and thus little natural protection from UV radiation, burn in the sun. People with more melanin will tan. The symptoms of sunburn will disappear, and a tan will fade. The long-term effects, however, are cumulative and the damage is permanent. Prolonged exposure to UV rays damages the genetic material in skin cells and causes it to undergo changes. These changes can eventually result in the formation and growth of can- cerous cells. Exposure to UV radiation is the leading cause of certain types of skin cancer. UV radiation also breaks down the elastic fibers
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