Wouldn’t you look strange walking around with your insides showing? Your skin is your body’s covering, but because it has a more important function than just covering your body, your skin is considered an organ of your body, the largest organ, at that!
The most important function of your skin is to keep your body at the right temperature. Since your body produces heat all the time, your body would become much too hot if this heat could not escape. Some of this heat escapes when you breathe, but most of it escapes through your skin when you sweat. Sweat, or perspiration, is made in glands beneath your skin. Sweat glands are tiny tubes that open up through the epidermis, or outer layer of your skin.
When you are in the hot sun or doing strenuous work, more blood passes through tiny blood vessels in your skin. These blood vessels dilate, or get bigger, placing the blood closer to the outside air. The sweat glands in the skin then become more active. They produce more sweat, which flows out of the pores, or openings on the surface of your skin. As the air outside dries off this sweat, your skin feels cooler.
When it is cold outside, these tiny blood vessels contract, or get smaller, keeping them away from the surface of your skin, where their heat would be lost to the cold air.
Your skin also contains oil glands which open up into hair follicles, or sacs, beneath your skin. These glands give off oil which makes your hair soft, smooth, and glossy, and keeps your skin from drying out.
You shed your skin continually and replace it with an entirely new outer layer once every 28 days!