Sweat is produced by dedicated sweat glands, and is a mechanism
used primarily by the body to reduce its internal temperature.
There are two types of sweat gland in the human body, the
eccrine gland and the apocrine gland. The former regulates body
temperature, and is the primary source of excreted sweat, with the
latter only secreting under emotional stresses, rather than those
involved with body dehydration.
Eccrine sweat glands are controlled by the sympathetic nervous
system and, when the internal temperature of the body rises, secrete
a salty, water-based substance to the skin’s surface. This liquid then
cools the skin and the body through evaporation, storing and then
transferring excess heat into the atmosphere.
Both the eccrine and apocrine sweat glands only appear in
mammals and, if active over the majority of the animal’s body, act as
the primary thermoregulatory device. Certain mammals only have
eccrine glands in specific areas – such as paws and lips – warranting
the need to pant to control their temperature.