Sweating-Physiology and Pathophysiology

Sweating is a function of the sweat glands which are present in the skin and widely distributed over the general body surface. Sweat is produced as a thermoregulatory response to heat, either from a rise in environmental temperature or endogenously from a rise in body temperature, e.g. during exercise. Evaporation of sweat from the skin causes cooling as long as the environmental humidity is not excessive. Thermoregulatory sweating occurs over the general body surface, while that which is associated with emotional states is seen mainly on the face, palms and feet. However, considerable differences in the sweating pattern, in response to various stimuli, are found between individuals. Sweating is abnormal when either too much (hyperhidrosis) or too little, or none (hypohidrosis or anhidrosis) is produced either generally or in particular regions of the body. Methods for measuring sweat production and the application of these techniques to studying the pathophysiology of the response are also discussed.