Humans depend on the cooling effects of perspiration. Perspiration helps maintain body temperature, skin hydration and fluid and electrolyte balance.

Perspiration is controlled by different regions of the brain. Temperature-related (thermoregulatory) sweating is controlled by the hypothalamus, the part of the brain that controls body functions, such as eating, sleeping and sexual behavior.  Sweating caused by emotions is controlled by the cerebral cortex, the outer layer of the brain. Sweat glands have nerve fibers that enable the brain to control sweating and regulate heat. This reaction is activated when a person’s core (internal) body temperature rises above the normal temperature of 98.6 degrees Fahrenheit (37 degrees Celsius).

Perspiration is the body’s natural way of regulating temperature. When the nerves indicate areas of heat in the body, messages are sent to the sweat glands to produce sweat. Stress or excitement can produce the same messages to the sweat glands to perspire. Sweat moves through ducts to the pores or hair follicles and reaches the skin. When sweat evaporates on the surface of the skin, it removes excess heat and has a cooling effect on the body.

In addition to heat regulation, perspiration has a minor role in waste disposal.  Sweat glands also excrete small amounts of waste products such as urea and ammonia (byproducts of protein metabolism) through perspiration, therefore eliminating them from the body. However, the majority of the body’s wastes are eliminated through the urinary system.