Draft Lesson – Varsity Education

Vocabulary: epidermis, dermis, melanin, sebaceous glands, hair follicles, melanoma

Your Skin
Main Idea: Skin protects you from pathogens, regulates your body temperature, and helps you feel sensations.

What’s the largest organ on the human body? You may be surprised to learn that the answer is the skin. The skin consists of two main layers, as shown in Figure 13.1. The epidermis is the outer, thinner layer of the skin that is com· posed of living and dead cells. Just underneath the dermis is the thicker layer of the skin beneath the epidermis that is made up of connective tissue and contains blood vessels and nerves. Cells in the epidermis make substances called lipids, which make your skin waterproof. This waterproofing helps the body maintain a proper balance of water and electrolytes. Other cells produce melanin, a pigment that gives the skin, hair, and iris of the eyes their color-the more melanin that your body produces, the darker the skin. The melanin in skin also helps protect the body from harmful ultraviolet (lJV) radiation that causes skin cancer.

The skin performs three main functions to keep you healthy:

protection. The skin protects you from pathogens and internal damage. It acts as a barrier to prevent bacteria and viruses from entering your system. If this barrier is broken by a cut or other wound, the skin repairs itself to keep pathogens from entering the body.
Temperature control. When your body temperature
begins to rise, the blood vessels in the skin dilate, allowing heat to escape through the skin’s surface. Sweat glands-structures within the dermis that release perspiration through ducts to pores on the skin’s surface-cool the skin. If body temperature begins to drop, the blood vessels in the skin constrict, reducing the amount of heat lost and helping to maintain body heat.
Sensation. 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 that are stimulated by changes in the outside environment. These receptors enable you to feel sensations such as pressure, pain, heat, and cold.

The dermis is a single thick layer composed of connective tissue, which gives the skin its elastic qualities. Sebaceous glands, structures 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 help remove wastes from body cells.

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Keeping Your Skin Healthy

Main Idea: A daily routine will keep your skin healthy.

Keeping your skin healthy should be an important part of your daily routine. Some of the ways that you can keep your skin health, include:

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.
Choose personal skin care products carefully to avoid irritation and the chance of allergic reaction.
Follow a well-balanced eating plan that is rich in vitamins and minerals, especially vitamin A. Milk, green and yellow vegetables, and liver are good for healthy skin.

UV Protection

Some people believe that tanned skin looks good. A suntan, however, is really a sign that the skin has been damaged by UV rays. When skin is exposed to UV radiation, melanin pro- duction is increased. The production in melanin is the skin’s way of trying to protecting itself from the UV rays. Prolonged exposure to UV rays can lead to skin cancer. To protect your skin from the sun’s damaging rays,

- always wear sunscreen on exposed areas of skin. Use an SPF of 15 or higher that blocks both UVB and lNA (the more penetrating) rays. Apply it 15 to 30 minutes before going outside, even on cloudy days.
- wear protective clothing, including hats, long-sleeved shirts, and long pants. UV rays are most intense between 10:00 A.M. and 4:00 P.M., and stronger at higher altitudes.
- wear sunglasses. Exposure to UV rays can damage the eyes, causing burns, cataracts, and even blindness.
- avoid using tanning beds. Tanning beds are not safe, and prolonged exposure can lead to skin cancer.

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Body Piercing and Tattooing

Piercing and tattooing practices have been around for thousands of years. Unlike using makeup or changing hair color, however, piercings and tattoos are permanent. Both carry potential health risks because they break the physical barrier of the skin. This can result in infection from bacteria and the transfer of blood-borne pathogens from viruses such as hepatitis B, hepatitis C, and HIV through non-sterile needles. The American Dental Association also warns that oral piercing can damage your mouth and teeth.

Skin Problems

Many skin problems can affect your self image, but are not life threatening. Check with a health care professional before purchasing any skin care product to make sure it’s right for you. Common skin problems include

Acne. When pores in the skin get clogged, bacteria causes inflammation, and pus forms. To treat acne, wash your face gently twice a day, apply over-the-counter treatments, and avoid using oily products or too much makeup. Touching and picking may cause scarring. Extreme cases may require prescription medication.

Warts. These are caused by a virus and are most commonly found on the hands, feet, and face. They can spread through direct contact with another person’s wart. Dermatitis, or eczema. This is an inflamed or scaly patch of skin, usually from an allergic reaction. Keeping the area well moisturized can help reduce the irritation. A doctor may prescribe medications to treat dermatitis.
Fungal infections. Ringworm and athlete’s foot are infections that can be spread by contact with skin or infected clothing, or in public showers. Keep the infected area clean and dry, and treat with over-the-counter medicines.
Boils. These form when hair follicles-sacs or cavities that surround the roots of hairs-become infected. The tissue becomes inflamed, and pus forms. Bursting or squeezing a boil can spread the infection. Treatment can include draining the pus and taking antibiotics.
Vitiligo. A condition in which patches of skin lose melanin and have no pigment is called Vitiligo (vih-tuh-LY-go). These areas are extremely susceptible to burning when exposed to UV light, so they should always be covered.
Moles. Though most moles are harmless, certain types may develop into melanoma, the most serious form of skin cancer, which can be deadly. Early detection and treatment are critical in controlling the spread of this cancer. See Figure 13.3 on how to monitor the appearance of moles. Report any changes to a dermatologist.

Your Hair

Main Idea: Your hair protects your skin from UV radiation and helps maintain body heat.

Hair grows on every surface of the skin, except for the palms of the hand and the soles of the feet. You have more than 100,000 hairs on your head alone. Although hair is com- posed of dead cells, living cells in the epidermis make new hairs and cause hair growth.

Hair helps protect the skin, especially the scalp, from exposure to UV radiation. The eyebrows and eyelashes protect the eyes from dust and other particles. Hair also reduces the amount of heat lost through the skin of the scalp.

Healthy hair begins with a well-balanced diet. Without proper nutrients, hair can become thin and dry. Daily brushing keeps dirt from building up and helps distribute the natural oils in your hair evenly. Regular shampooing will keep your hair healthy. It’s best to limit the use of harsh chemical treatments such as dyes, bleach, or permanents. Also, avoid excessive use of heating irons or hot combs. Overexposure to these can cause hair to become dry and brittle.

Hair Problems

Normally, oil produced by sebaceous glands protects the skin from drying out and keeps hair soft and shiny. Dandruff-the dead skin cells that are shed as sticky white flakes when the scalp becomes too dry-usually can be treated with an over-the-counter dandruff shampoo. If itching or scaling persists, consult a health care professional who may prescribe another type of treatment.

Head lice are tiny parasitic insects that live in the scalp hair of humans. They feed on blood by biting through the skin of the scalp. Lice can infect anyone and are mainly transmitted by head-to-head contact or by using objects such as brushes, combs, or hats that have been used by an infected person. Using a medicated shampoo can kill the organisms. Washing sheets, pillowcases, combs’ and hats with hot water and soap, as well as frequent vacuuming at home, can help prevent the spread of head lice or a repeat infection.

Your Nails

Main Idea: Nails help protect your fingers and toes.

Like your hair, your fingernails and toenails are made of closely packed dead cells that contain keratin. Cells beneath the root of the nail divide and multiply, causing the nail to grow. Nails protect and support tissues of fingers and toes.

Good care of the nails includes keeping them clean and evenly trimmed, which helps prevent split nails and hangnails. Use a nail file to shape and smooth nails, and keep cuticles pushed back. A cut, split, or break in the skin around the nail allows pathogens into the body and may lead to infection. Keep the area clean and apply an antibiotic ointment if necessary.

Trim toenails straight across and just slightly above the skin level to reduce the risk of infection and ingrown nails. Keeping nails short also reduces the risk of fungal infections under the nails. Fungal infections can be treated with anti-fungal medications.