The skin has five basic functions:

1. Protection. The skin protects the body from many environmental factors; it acts as a physical barrier for protection from invading microbes, ultraviolet radiation, abrasions and harmful substances. It also provides a barrier to prevent fluid loss.

2. Sensation. Superficial nerves and receptors relay information to the nervous system. This is further discussed in the next section, Cutaneous Receptors.

3. Containment. The skin contains all the structures within the body, from muscle to organs. It also keeps vital substances such as fluids contained, which is especially important in preventing dehydration.

4. Thermoregulation. Sweat glands and blood vessel state help to conrol heat loss through the skin. Sweat produced from sweat glands cools the skin and vasodilation of the vessels increases heat loss through ratiation. Vasoconstriction reduces heat loss through the skin and contraction of arrector muscle of the hair makes hairs stand on end, providing an insulating layer.

5. Storage. Synthesis and storage of Vitamin D occurs in the skin.