Understanding the Skin | The Functions of the Skin

Understanding the Skin
A person’s skin covers, on average, an area of more than 20 square feet and accounts for approximately 15 percent of body weight. Our largest organ, the skin is far more than merely a thing of beauty. Complex and constantly changing, the skin plays an active role in our general health and well-being.
As you’ll find when you read this book, there are many easy things you can do to take care of your skin and keep it at its best. Despite the fact that the skin is tough and resilient, problems do occur. According to the American Academy of Dermatology (AAD), some 7 million Americans each year visit a practitioner for advice on a new skin problem. The U.S. Department of Health and Human Services reports that skin diseases are to blame for 3 million lost work days annually. In addition, nearly 7 percent of the military population is affected by skin problemsfor example, rashes and infectionsmaking skin conditions the fourth largest cause of disability in the armed forces, claims the AAD.
Before we delve into what can go wrong with the skin, however, let’s take a look at what’s happening when everything is going right.

The Functions of the Skin

The immediate task of the skin is to act as a barrier. The visible layer of the skin, which consists of dead skin cells, serves as the immune system’s first line of defense against bacteria, parasites, and other organisms trying to enter the body. In the event an invader does make ?it through, the skin calls in a cavalry of immune system cells to ward off the infection. The skin also works to protect internal muscles, tissues, and organs from injury, cushioning them from bumps and bruises with its shock-absorbing layer of fat.
The skin is waterproof (otherwise you’d soak up water like a sponge by just taking a shower), but it is not merely a barrier, it is also a gatekeeper. Some substances can be absorbed through the skinfor example, medications administered in ”patch” form. Similarly, some dangerous chemicals, such as arsenic, can also gain entry to the body through the skin.
Temperature regulation is another main job of the skin. When the brain signals that the body’s temperature is rising, glands within the skin secrete sweat onto the skin’s surface, where it evaporates, releasing body heat (and also, conveniently some of the body’s waste products). In addition, blood vessels within the skin dilate, bringing the blood closer to the surface so that heat may be dissipated.
When body temperature drops, the same blood vessels contract and restrict blood flow. Because the blood is kept from the surface of the skin, less body heat is lost. The contraction of the vessels causes the contraction of nearby erector pili muscles attached to hair follicles within the skin: Thus we have, in medical terms, cutis anseriaor goosebumps.
Of course, the skin is also the organ through which we experience the sense of touch. In fact, all of our sensory tissuesthose of the ears, the eyes, the tongue, and the noseare created from the same type of cells (called epithelial cells) that make up the skin. The network of nerves in the skin allows us to gather information about our surroundings, alerts us to dangers (such as a hot stove), and allows us to feel pleasure as well as pain.
As if that isn’t enough, the skin also contributes to good health by taking part in the production of vitamin D. Synthesized in a reaction between chemicals in the skin and sunlight, vitamin D is important for normal growth and development: Its presence is necessary in order for the body to absorb calcium, a mineral crucial to bone formation and strength.
The skin is also in many ways a barometer of health. It reflects the negative effects that smoking and alcohol and drug use have on the body. Stress, as well, can take its toll on the appearance of the skin.
Many physical conditions also have symptoms that manifest themselves in changes to the skin: A symptom of chicken pox, for example, is a skin rash; liver disease sometimes appears as jaundice; and illegal drug use may trigger sallow skin or blemishes (marijuana use often causes hives and acne flare-ups). For these reasons, the skin is important to any practitioner looking for a diagnosis because it provides valuable clues to what may be going on beneath the surface.
(People’s Medical Society)