Perspiration is an important component of the body’s cooling system. Produced in sweat glands within the skin, perspiration cools the body when exposed to heat in a process called thermoregulation. There are two types of sweat glands in the human body—eccrine sweat glands and apocrine sweat glands. Both types come into play when the body’s temperature needs to be cooled, though appocrine sweat glands have a smaller, secondary function—scent production.
Function
Both eccrine and apocrine sweat glands take part in thermoregulation. The glands, which Dr. Farris of NuSkin describes as “long, coiled hollow tubes of cells,” empty onto the surface of skin. When the ambient temperature rises above 98.6 degrees Fahrenheit, the body’s resting temperature, temperature receptors on the skin and thermo-sensitive neurons in the brain alert the body to begin producing sweat. The sweat carries heat away from the body’s core, thereby decreasing core temperature. As the sweat evaporates, in an event called “evaporative cooling,” heat transfers from a liquid to a vapor, decreasing surface temperatures as well.
Eccrine Sweat Glands
Eccrine sweat glands are present at birth, located mainly on the palms of the hands, the soles of the feet, and the forehead. Smaller quantities exist everywhere else on the body, with the exception of the lips, the nail beds and the external genitalia.
The sweat produced by eccrine sweat glands is made up mostly of water. A small amount of salts, trace elements, heavy metals and organic compounds can also be found in this kind of sweat. According to the American Academy of Dermatology, when a person sweats under the arms, the wet portion of the sweat is supplied by the eccrine sweat glands.
While ambient heat and muscle heat are the main reasons the eccrine sweat glands produce perspiration, they can also produce sweat in response to strong emotions. Referred to as “emotional sweat,” this type of perspiration is released through the palms of the hands, the soles of the feet and the forehead. A study published by the National Center for Biotechnology Information reports that stress and emotion cause emotional sweat.
Apocrine Sweat Glands
Apocrine sweat glands are mostly located in the axillae (underarms) and in the anogenital region. They are small and non-functional until puberty and produce a more viscous liquid than do eccrine sweat glands. The sweat produced by apocrine glands is odorless until it reaches the surface of the skin, where bacteria that live on the skin break down the organic components of the perspiration.
According to the American Academy of Dermatology, apocrine sweat glands are scent glands. An article in “Science Friday,” supported by research conducted at The Athena Institute by Dr. Winifred Cutler, explains that perspiration might have a pheromone component, which suggests that the body might produce this type of sweat as a biological, and possibly sexual, trigger.
