IntroductionMany people would be surprised to learn that the skin is an organ. Along with other organs, such as sweat glands and hair, the skin makes up the integumentary system. Investigating how the var-ious parts of the integumentary system work together can help you see how the integumentary system as a whole fulfills its primary function—to protect all other internal parts of the body from external factors, such as temperature variations, infectious microorganisms, and contami-nants. The integumentary system also works with other body systems, such as the nervous, car-diovascular, and muscle systems, to help keep the body in a state of balance, or homeostasis. It isimportant to understand how this body system works to understand disorders that affect it and how to effectively prevent and treat such diseases. Protection from DamageThe skin functions in the body in many different ways. It is specifically adapted to meet many different needs of the body. Protection is the first important function of the integumentary system. The skin protects you from three main types of damage.Physical damage: The skin is a relatively strong physical barrier, especially on parts of the body that tend to come in contact with damaging substances, such as the palms of your hands and soles of your feet. You can even build your skin up if you need to, such aswhen you build calluses on your hands after continued use.Microbes: When the physical barrier of the skin is compromised and becomes damaged—as from a cut, burn, or something more serious—the body loses its first line of defense to foreign bodies and microbes. The skin provides a protective barrier for the internal structures of the body. Think of all the invaders in your environment that can cause problems for your body—bacteria, viruses, fungi, parasites, and many types of pollutants.
UV Radiation: The skin protects you against damaging ultraviolet radiation from the sun. Although it is important to use sunscreen when you are out in the sun for long periods of time, think about the kind of damage your internal tissues might incur if you didn’t have the skin’s protection.RegulationIn addition to protection, the body helps maintain homeostasis, or balance, in the body by regulating body temperature. The body works best at an optimal temperature of 98.6 degrees. If the body’s temperature increases or decreases too much away from 98.6 degrees, it can become damaged or even die. Hypothermia is when the body’s temperature falls too low. Heat exhaustionand heat stroke are serious consequences of the body’s temperature rising too high. Both of theseconditions can be fatal.Temperature RegulationTo keep the body from straying too far from its optimal temperature, the skin works with the cardiovascular system to regulate the release or conservation of heat.