Sweating, along with vasodilatation, is one of the body's means of reducing temperature. The signal to increase the rate of sweating arises from the hypothalamic sympathetic outflow to eccrine sweat glands.
Heat is lost from the surface of the skin as the energy used to evaporate sweat. The evaporation of one gram of water uses 2.4kJ of heat. Typically, every hour there is a basal, insensible evaporative loss of water of about 20-30 grams from both skin and lungs.
The rate of sweating is dependent upon core as well as surface body temperature. It occurs at a higher core temperature if the surface temperature is lowered, and vice versa.
The capacity of sweating to reduce temperature is dependent upon external humidity. Hence, in high humidity environments e.g. rain forest, a lower temperature is tolerated than low humidity settings e.g. desert.
Last reviewed 01/2018