Allergies
Asthma
Skin,
and Hair
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The skin is our largest organ. If the skin of a typical 150-pound adult male were stretched out flat, it would cover about 2 square yards and weigh about 9 pounds. Our skin protects the network of tissues, muscles, bones, nerves, blood vessels, and everything else inside our bodies. Our eyelids have the thinnest skin, the soles of our feet the thickest.
Hair is actually a modified type of skin. It grows everywhere on the human body except the palms of the hands, soles of the feet, eyelids, and lips. Hair grows more quickly in summer than winter, and more slowly at night than during the day.
Nails are also a type of modified skin - and they're not just for beauty. Nails protect the sensitive tips of our digits.
How Are Skin, Hair, and Nails Necessary for Living?
Essential to a person's survival, the skin forms a barrier that prevents harmful substances and microorganisms from entering the body. It protects body tissues against injury and prevents the loss of life-sustaining fluids that bathe body tissues. It also helps to regulate body temperature through perspiration and protects us from the damaging ultraviolet rays of the sun. Without the sensory nerve cells in our skin, we couldn't feel touch, warmth, cold, or other sensations.
The hair on our heads keeps us warm by preserving heat and also serves a cosmetic function. The hair in our nose, ears, and around our eyes provides protection from dust and other foreign particles. Our eyebrows and lashes protect the eyes by decreasing the amount of light and particles that enter them. The fine hair that covers our bodies provides warmth and protects our skin. Hair also cushions our bodies against injury.
Human nails are not necessary for living, but they are an indicator of a person's general health, and illness often affects their growth. They provide support for the tips of the fingers and toes, protect them from injury, and aid in picking up small objects. Without them, we'd have a hard time scratching an itch or untying a knot.
Diseases, Conditions, Disorders, and Dysfunctions
It's important to keep the skin, hair, and nails clean because many disease-causing organisms can infect them. Some of the more common diseases and conditions include:
Disorders of the scalp and hair:
Tinea capitis, also known as ringworm, is not a worm at all but a type of fungal infection that forms a scaly, ring-like lesion in the scalp. It's highly contagious and common among school-age children.
Alopecia is an area of hair loss. Ringworm is a common cause of alopecia in children. Alopecia areata (rapid hair loss in round or oval patches on the scalp) is a rarer condition with unknown causes, although stress has been suggested as a contributing factor.
Disorders of the skin:
Dermatitis is any inflammation of the skin. There are many different types of dermatitis, including:
- Atopic dermatitis, also called eczema, is a common hereditary dermatitis that causes an itchy rash primarily on the cheeks, face, trunk, and the arms and legs. It usually develops in infancy, but can also occur in early childhood. It may be associated with other allergic diseases such as asthma and allergic rhinitis.
- Contact dermatitis is an inflammation that occurs when the skin comes in contact with an irritating substance. The most well-known cause of contact dermatitis is poison ivy, but there are many others, including chemicals found in laundry detergent, cosmetics, and perfumes. Substances found in urine and feces can result in diaper dermatitis.
- Seborrheic dermatitis, common in newborns and adolescents, is caused by an overproduction of sebum from the sebaceous glands and results in a greasy rash on the scalp, face, chest, and groin area.
Bacterial infections of the skin
- Impetigo. A condition that affects mostly children, impetigo is a bacterial infection that results in a honey-colored, crusty rash, usually on the face near the mouth and nose.
- Cellulitis. Cellulitis is an infection of the skin and subcutaneous tissue that often occurs when bacteria are introduced through a puncture, bite, or other break in the skin. The cellulitic area is usually warm and tender and has some redness.
- Streptococcal and staphylococcal infections. In addition to being the main causes of cellulitis and impetigo, these two types of bacteria are responsible for distinctive rashes on the skin, including the rashes associated with scarlet fever and toxic shock syndrome.
Fungal infections of the skin
- Candidal dermatitis. A warm, moist environment, such as that found in the folds of the skin in the diaper area of infants, is perfect for growing the yeast candida. Candidal dermatitis is also a common vaginal infection in adolescent girls.
- Tinea corporis (ringworm). The same type of fungus that causes ringworm in the scalp (tinea capitis) can cause scaly, ring-like lesions anywhere on the body.
- Tinea pedis (athlete's foot), is an infection of the feet that's also caused by the same type of fungus that causes ringworm on the scalp and body. Athlete's foot is commonly found in adolescents and usually appears during warm weather.
Other skin infections
- Viral infections. Many viruses cause characteristic rashes on the skin, including varicella (chicken pox and shingles), herpes simplex (which causes cold sores), papillomavirus (which causes warts), measles, mumps, parvovirus, and a host of others.
- Infestations. When the skin is infested by parasites (usually tiny insects or worms) that burrow into the skin, the result is often an itchy rash. Scabies and lice are examples of infestations. Both are highly contagious.
Acne (acne vulgaris). Acne is the single most common skin condition in children. Some degree of acne is seen in 85% of adolescents. Acne is the result of clogged sebaceous follicles - a condition that worsens with the hormonal changes of puberty. It is also seen in newborns (neonatal acne), although the causes are unknown.
Skin cancer. Even though skin cancer is rare in children, it's crucial that good sun care habits are established during childhood. The use of sunscreen and other sun protection measures can help prevent melanoma (a serious form of skin cancer that can spread to other parts of the body) later in life, especially among fair-skinned people who sunburn easily.
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