Perspiration is a secretion of fluids through sweat glands on the skin surface of mammals. Humans have two types of sweat glands: eccrine and apocrine. Eccrine glands secrete watery, clear sweat composed mainly of water and ions as sodium, magnesium, calcium, potassium and other trace elements. This sweat also contains lactate and urea which causes its typical yellowish colour of the sweat patches. Apocrine glands secrete mainly sweat containing proteins and lipids and its consistence is more viscous than eccrine glands sweat. Apocrine glands sweat is further degraded by bacteria which produce aromatic elements causing strong odour.
Why do we perspire?
In the human body perspiration is predominantly a way of regulating body temperature. This is achieved especially by eccrine sweat glands which are fully functional from early age and are located all over the human body. However, they are more present on palms, soles, in armpits and in the groin. Apocrine sweat glands start to form during adolescence and carry pheromones. Apocrine glands can be found especially in armpits, groin and around nipples.
How does perspiration work?
Cooling of the body is caused by liquid evaporating off the skin. This way the heat from the skin is released thus changing water into gas. Apart from thermoregulation processes, sweating is associated with nervousness as an evolutionary relic connected with preparation for fight or escape, i.e. activities requiring warmed-up muscles. (E.g. cats and dogs have minimum sweat glands therefore they cool off by rapid breathing with their tongue stuck out.)