Section 14.2 Your Skin, Hair, and Nails Slide 1 of 26 The skin covers and protects the body from injury, infection, and water loss. Your Skin The skin also helps to regulate body temperature and gathers information from the environment. Protection The skin shields and protects the organs and tissues beneath it. Temperature Regulation When you are warm, sweat glands in the skin produce perspiration, which cools your body. When you are cold, the blood vessels narrow, keeping more heat within your body. Information Gathering Nerves in the skin provide information to your central nervous system about outside factors.

Section 14.2 Your Skin, Hair, and Nails Slide 2 of 26 The outermost layer of your skin is the epidermis (ep uh DUR mis). The Epidermis The dead cells in skin contain a protein called keratin that makes the skin tough and waterproof. Cells deep in the epidermis produce the protein melanin, a dark pigment that gives skin some of its color.

Section 14.2 Your Skin, Hair, and Nails Slide 3 of 26 The dermis (DUR mis) is the tough, elastic layer of skin that lies below the epidermis. The Dermis A tiny opening on the surface of the skin is called a pore. Strands of hair grow within the dermis in structures called follicles. Oil is secreted into follicles by sebaceous glands.

Section 14.2 Your Skin, Hair, and Nails Slide 4 of 26 Layers of the Skin Epidermis Dermis Fat Sweat gland Hair follicle Nerve Blood vessels Sweat droplet Pore Hair Sebaceous gland

Section 14.2 Your Skin, Hair, and Nails Slide 5 of 26 Eating a balanced, healthy diet; drinking plenty of water; and sleeping enough will keep your skin healthy. Caring for Your Skin The most important things you can do for your skin are to avoid damage from the sun and tanning lamps and to monitor moles.

Section 14.2 Your Skin, Hair, and Nails Slide 6 of 26 Overexposure to ultraviolet (UV) radiation can lead to skin cancer, including a sometimes deadly form called melanoma. Preventing Skin Damage When you are outside, it is important to wear sunscreen that blocks UVA and UVB rays. Sunscreen should be reapplied frequently.

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Section 14.2 Your Skin, Hair, and Nails Slide 8 of 26 The first sign of melanoma is usually an irregularly shaped mole, or brown spot, that increases in size. Monitoring Moles The mole may become blue-black or have blackish spots.

Section 14.2 Your Skin, Hair, and Nails Slide 9 of 26

Section 14.2 Your Skin, Hair, and Nails Slide 10 of 26 One common skin problem in teens is acne. Treating Acne Acne forms when excess oil and dead cells plug a hair follicle. Products that contain benzoyl peroxide can help mild cases of acne. A dermatologist is a doctor who specializes in treating skin problems.

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Section 14.2 Your Skin, Hair, and Nails Slide 12 of 26 Eczema (EK suh muh) is a condition in which an area of skin becomes red, swollen, hot, and itchy. Treating Eczema In most cases, eczema can be treated with a medication applied to the skin. Sometimes the skin blisters and oozes.

Section 14.2 Your Skin, Hair, and Nails Slide 13 of 26 Boils Boils are swollen, painful infections of hair follicles caused by bacteria. Treating Skin Infections Warts Warts are hardened growths on the skin that are also caused by a virus. Cold Sores Cold sores are clusters of watery blisters caused by a virus. Ringworm The ringworm fungus, which is highly contagious, produces red, scaly, ring-shaped patches on the skin. Athlete’s Foot Causes burning, itching, cracking, and peeling of the skin on the feet and between the toes.

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Section 14.2 Your Skin, Hair, and Nails Slide 15 of 26 Hair protects the scalp from sunlight and provides insulation from the cold. Your Hair Hairs in the nostrils and ears and your eyelashes, prevent debris from entering the body.

Section 14.2 Your Skin, Hair, and Nails Slide 16 of 26 Frequent brushing of your hair will remove excess dirt and make your hair shine. Care for Your Hair Shampooing removes dirt and oil buildup from sebaceous gland secretions.

Section 14.2 Your Skin, Hair, and Nails Slide 17 of 26 Head lice are small insects that live on the scalp and lay their eggs on hair. Hair Problems The best way to prevent infections is to avoid sharing combs, brushes, or hats. Dandruff occurs when the epidermal cells of the scalp are shed at a faster than normal rate. Some factors that may contribute to dandruff are fungal infections, overactive oil glands, stress, and heredity.

Section 14.2 Your Skin, Hair, and Nails Slide 18 of 26 Nails grow from an area of rapidly dividing cells near the tips of fingers and toes. Your Nails The tough, platelike nails cover and protect the tips of your fingers and toes, which come in frequent contact with objects in your environment.

Section 14.2 Your Skin, Hair, and Nails Slide 19 of 26 Keeping your nails clean will help prevent the spread of infectious microorganisms to other parts of your body and to other people. Caring for Your Nails Clip and file your nails so that their edges are smooth. Avoid biting your nails.

Section 14.2 Your Skin, Hair, and Nails Slide 20 of 26 An ingrown toenail results when the sides of a toenail grow into the skin. Nail Problems If not treated properly, ingrown nails can become infected. Fungal infections of the nails are common in people who often have wet hands or feet. Infected nails appear thick and discolored with white markings.

Section 14.2 Your Skin, Hair, and Nails Slide 21 of 26 Vocabulary epidermisThe outermost layer of skin. keratin A protein in dead skin cells of the epidermis that makes skin tough and waterproof. melanin A pigment released in the epidermis that gives skin color and causes skin to tan. dermis A tough, elastic layer of skin that lies below the epidermis. pore A tiny opening in the skin through which sweat is secreted. follicleA skin structure in which a strand of hair grows and oil is secreted.

Section 14.2 Your Skin, Hair, and Nails Slide 22 of 26 Vocabulary sebaceous glandA gland that secretes oil into a hair follicle in the skin; the oil softens and moistens hair and skin. melanoma A serious form of skin cancer. acne A lesion that forms when excess oil and dead cells plug a hair follicle. dermatologist A doctor who treats skin problems. eczemaA condition in which an area of irritated skin becomes red, swollen, hot, and itchy.