Functions of the Integumentary System

FUNCTIONS OF THEINTEGUMENTARY SYSTEM

The integumentary (in-teg-̄u -men′tă -rē ) system consists of the skin and accessory structures, such as hair, glands, and nails. Integument means covering, and the integumentary system is one of the more familiar systems of the body to everyone because it covers the out-side of the body and is easily observed. We are also familiar with this system because we are concerned with the appearance of the integumentary system. Skin without blemishes is considered attrac-tive, whereas acne is a source of embarrassment for many teenagers. The development of wrinkles and the graying or loss of hair are signs of aging that some people find unattractive. Because of these feelings, we invest much time, effort, and money on changing the appearance of the integumentary system. Many of us apply lotion to our skin, color our hair, and trim our nails. We also try to prevent sweating by using antiperspirants and to reduce or mask body odor by washing and by using deodorants and perfumes.

 The appearance of the integumentary system can indicate physiological imbalances in the body. Some disorders, such as acne or warts, affect just the integumentary system. Other dis-orders affect different parts of the body but are reflected in the integumentary system, providing useful signs for diagnosis. For example, reduced blood flow through the skin during a heart attack can cause a person to look pale, whereas increased blood flow as a result of fever can cause a flushed appearance. Also, some diseases cause skin rashes, such as those characteristic of measles, chicken pox, and allergic reactions. In addition, the integ-umentary system and the other systems often interact in complex ways in both healthy and diseased states (see Systems Pathology, “Burns,” later).

 Although we are often concerned with how the integumentary system looks, it has many important functions that go beyond appearance. Major functions of the integumentary system include

1.Protection. The skin provides protection against abrasionand ultraviolet light. It also prevents microorganisms from entering the body and reduces water loss, thus preventing dehydration.

2.Sensation. The integumentary system has sensory receptors that can detect heat, cold, touch, pressure, and pain.

3.Vitamin D production. When exposed to ultraviolet light,the skin produces a molecule that can be transformed into vitamin D, an important regulator of calcium homeostasis.

4.Temperature regulation. The amount of blood flow beneath the skin’s surface and the activity of sweat glands in the skin both help regulate body temperature.

5.Excretion. Small amounts of waste products are lost through the skin and in gland secretions.