Jane Gabrielson, age 13, of Lexington, N.C., for her question:
WHAT IS SKIN?
Probably the single most important thing you can do for your skin is to keep it clean. This keeps the small pores, or gland openings, from becoming clogged. It can also help to prevent the spread of infection on the skin. A clean skin can also keep germs under control since they can infect the skin and bring about inflammations and rashes.
Your skin is actually your body's largest organ. It's an organ because it performs many important functions. Perspiration is given off through the skin. And your body's temperature is regulated in part by your skin.
A piece of your skin the size of a quarter will contain about three feet of blood vessels, 12 feet of nerves, 25 nerve ends, 100 sweat glands and more than 3 million cells. An adult human's skin, if spread out flat, would cover about 18 square feet and it would weigh about six pounds.
Your skin has two basic parts: the surface which is called the epidermis, or corneum, and a lower layer which is called the dermis, or corium.
Twelve to 15 rows of cells make up the epidermis. They grow from the bottom up, so when they finally reach the surface they are shed as thin flakes. The flakes are the dead skin which you can rub off with a towel after taking a shower.
Some nerves are found in the lower cells, but there are no blood vessels. Any cut which draws blood must be deep enough to reach the dermis.
The epidermis is also responsible for the color of the skin. Dark races have a lot of pigment in the lower layers of the epidermis. Freckles are caused by pigment.
The dermis is made up of a network of connective tissue. In the dermis are found blood vessels, vessels for carrying the lymph, nerves, glands and hair follicles.
Wrinkles in the skin happen when the fat and other soft parts below the dermis are absorbed into the body and the skin itself does not shrink at the same rate.
There are about 2 million sweat glands distributed over the surface of your body. They are close together in the palms of your hands, in your armpits, on the soles of your feet and on your forehead.
The skin also has many oil glands with most of them opening in hair follicles. They give off an oily substance that makes the hair glossy and keeps the scalp from getting too dry.
A small amount of blood flows through the skin and it helps to regulate body heat. If the body needs to give off heat, the blood vessels in the skin expand and place the blood closer to the outside air. When there's a need to conserve heat, the blood vessels tend to contract and thus