Chapter 7 ? Skin The medical branch of science that deals with the study of skin and its nature, structure, functions, disease, and treatment is called Dermatology. A dermatologist is a physician engaged in the science of treating the skin, its structures, functions and diseases. An esthetician is a specialist in the cleansing, preservation of health, and beautification of the skin and body. Functions of the skin Protect Sensation Heat regulation Excretion Secretion Absorbsion Skin Specifics Protects muscles, bones, nerves. Barrier against environment Eyelids have thinnest skin Coles of feet are the thickest Continued pressure causes callus. Healthy skin is Slightly moist Soft and flexible Smooth and fine-grained texture Possesses a slightly acid reaction The appendages of the skin include Hair Nails Sweat glands Oil glands Skin is composed of two main divisions: The epidermis and the dermis. Epidermis is the outermost layer commonly called cuticle or scarf skin. Thinnest layer of skin and forms protective covering; contains no blood vessels; has nerve endings. basal cell layer, formerly known as stratum mucosum. Deepest layer responsible for growth of epidermis. Contains pigment, called melanin also found in hair. Pigment protects skin cells from destructive effects of excessive ultraviolet rays by means of cells called melanocytes which produce the melanin Stratum Spinosum The spiny layer is found just above the basal cell layer. Stratum Granulosum Granular layer consisting of cells that look like granules. Cells ar almost dead and are pushed to surface to replace those that are shed from stratum Corneum. Stratum Lucidum Clear layer consisting of small, transparent cells through which light can pass. Stratum Corneum Horny (outermost layer.) Its scale-like cells are constantly shed and replaced. Cells contain protein keratins which are combined with a think covering of oil making the skin almost waterproof. Dermis is the Underlying or inner layer of skin. Also called derma, corium, cutis or true skin. About 25 times thicker than epidermis. Highly sensitive; contains blood vessels, lymph vessels, nerves, sweat and oil glands, hair follicles, arrector pili muscles, and papillae. Made up of two layers: The papillary or superficial layer and the reticular or deep layer. Papillary Layer ? the outermost layer of the dermis, lying directly beneath epidermis. Contains small cone shaped projections (called papillae) or elastic tissue that point upward to epidermis. Some papillae contain looped capillaries. Others contain nerve-fiber endings for the sense of touch called tactile corpuscles; contains some melanin. Reticular Layer ? deeper layer of the dermis; contains fat cells, blood and lymph vessels, sweat and oil glands, hair follicles, and arrector pili muscles. Supplies skin with oxygen and nutrients. Subcutaneous Tussue - Fatty layer found below dermis; also called adipose or subcutis tissue; varies in thickness according to age, sex, and general health. Gives smoothness and contour to body; contains fats for energy and acts as protective cushion for outer skin. Circulation is maintained through arteries and lymphatics. How the skin is nourished. Blood supplies nutrients or molecules from food such as protein, carbohydrates, and fats to the skin. The nutrients are required for cell life, repair, and growth. Lymph bathes the skin cells and removes toxins and cellular waste. Networks of arteries and lymph vessels in the subcutaneous tissue reach the hair papillae, hair follicles, and skin glands. Phomelanin Red to yellow in color Eumelanin Dark brown to black Hereditary ? varies among races and nationalities. Dark skin contains more melanin; light skin contains less. Strength and flexibility of skin Two structures, collagen and elastin, make up 70% of the dermis and give strength, form, and flexibility to skin. Collagen ? a fibrous protein that gives skin form and strength. Healthy collagen fibers allow skin to stretch and contract. If fibers become weakened, skin can lose tone and suppleness, wrinkle, and sag. Elastin ? a protein base similar to collagen that forms elastic tissue. Gives skin flexibility and elasticity; helps skin regain its shape even after repeated stretching and expanding. Glands of the skin Skin contains two types of duct glands that extract materials from the blood to form new substances. Sudoriferous or sweat glands Consist of a coiled base or secretory coil and a tube like duct that terminates at the skin surface to form the sweat pore. Sweat glands are more numerous on palms, soles, forehead, and armpits. They regulate body temperature and help eliminate waste; activity is increased by heat, exercise, emotions, and certain drugs. Excretion of sweat is controlled by nervous system. Normally 1 to 2 pints of salty liquid are eliminated daily. Sebaceous or oil glands. Consist of little sacs whose ducts open into hair follicles. They secrete sebum that lubricates skin and preserves softness of hair. These glands are found everywhere on the body except palms and soles. Sebum flows through oil ducts leading to the mouths of hair follicles; when it becomes hardened and the duct becomes clogged, a blackhead is formed. Functions of the skin Protection: protect body from in jury and bacterial invasion. Outermost layer covered with thin layer of sebum to make it waterproof. Sensation: Responds to heat, cold, touch, pressure, and pain Heat regulation: protects the body from the environment. Excretion: Perspiration takes salt and other chemicals with it. Secretion: Oil lubricates skin and keeps it soft and pliable and hair soft; emotional stress can increase flow if sebum. Absorption: Limited, but does occur. Through the use of creams, female hormones and fatty materials such as lanolin can be absorbed through hair follicles and sebaceous gland openings. Maintaining Health of Skin The old adage, you are what you eat still holds true. Proper diatary choices help regulate hydration, oil production, and overall function of the cells. Eating foods found in all three basic food groups: fats, carbohydrates, and proteins, is the best way to support healthy skin. Vitamins and Supplements Aid in healing, softening, and fighting disease of the skin. Taking vitamins internally is best to support healthy skin. Also, some external applications have been found to be useful in nourishing skin. Vitamin A Supports overall health of the skin Aids in health, function, and repair of skin cells An antioxidant that can help prevent skin cancer. Can improve skin?s elasticity and thickness. Retinoic Acid or Retin-A is a topical form that can be used to treat acne. Vitamin C Also known as ascorbic acid Needed for proper repair of skin and tissues Speeds up healing process Promotes collagen production and fights the aging process. Vitamin D Best source is sunlight (in limited amounts); fortified milk and orange juice. Promotes healthy skin Promotes rapid healing of skin Also supports bone structure. Vitamin E Also known as tocohperol. Used with vitamin A, Can fight against and protect skin from harmful effects of sun?s rays. Helps to heal damage to skin?s tissues weather used internally or externally. Topically, it can help heal structural damage of skin including severe burns and stretch marks. Water and the skin No one can live without water, an essential nutrient. Composes 50 to 70% of body?s weight. Sustains the health of the cells Aids in elimination of toxins and waste. Helps regulate body?s temperature. Aids in proper digestion. Water needs vary. Use this formula: Divide body weight by 16. The resulting number approximates how many 8-ounce glasses of water you should drink every day. Dehydration 75% of Americans are chronically dehydrated.
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