Our skin plays an important function in maintaining a normal body temperature. When the body overheats, fewer nerve impulses go to the blood vessels in the skin, causing them to dilate, which increases the flow of warmth to the skin where it is cooled, promoting heat loss. Sweat glands too are activated, excreting waste in the form of a salt-rich substance which evaporates off the skin’s surface. This account for up to 90% of the body’s cooling.
Conversely, a similar process also exists in order to warm the body up. Fat cells present in the skin act as insulation against cold temperatures. When the body gets too cold, more nerve impulses are sent to the blood vessels in the skin, which causes the vessels to narrow. This restricts the blood flow to the skin and reduces the heat loss. Numerous temperature sensors present in the skin also stimulate the skeletal muscles, which causes brief muscular contractions, called shivering, which generate heat.
The skin also possesses remarkable self-healing properties, especially when just the epidermis gets damaged. When any injury occurs to an area of the body with a rich blood supply, even the dermis may get completely healed. Deeper wounds which penetrate the underlying tissue get healed by a process of scar formation. But scar tissue lacks the infection-resisting as well as metabolic functions of normal, healthy skin. Thus, extensive skin loss due to widespread burns or wounds may even cause death.