Sweat or perspiration is a watery fluid excreted by the sweat (sudoriparous) glands of the skin of mammals.
Sweat is exuded or excreted from the skins suboriferous glands—sweat glands.
Human eccrine sweat is composed chiefly of water with various salts and organic compounds in solution.
Animals with few sweat glands, such as dogs, accomplish similar temperature regulation results by panting, which evaporates water from the moist lining of the oral cavity and pharynx.
Apocrine sweat glands are limited to only certain locations in humans, unlike eccrine glands, and they do not function in thermoregulation but rather serve as scent glands.
Emotional stress, nervousness, and excitement increases the production of sweat from the apocrine glands, or more precisely, the sweat already present in the tubule is squeezed out.
Eccrine sweat glands are distributed over almost the entire surface of the body in humans and many other species, but are lacking in some marine and fur-bearing species.
The urocanic acid in sweat also may offer protection for the skin against ultraviolet radiation (Kent 2006).
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Eccrine sweat glands are coiled tubular glands derived from the outer layer of skin but extending into the inner layer.
The sympathetic nervous system regulates sweating, although the process can be stimulated by parasympathetic drugs (Stocking and Gubili 2004).
Among domestic animals, cattle have a high sweat rate of about 150 g/m2/h at 40 degrees centigrade, while sheep lose but 32 g/m2/h and dogs lose but an insignificant amount (Blood et al.
The sweat glands are controlled by sympathetic cholinergic nerves, which are controlled by a center in the hypothalamus.
Sweating occurs even in cool weather but is particularly pronounced in hot or humid conditions and during periods of stress or physical exertion.
During exercise or in hot or humid conditions, the copious sweating in the armpits is not from the apocrine glands but actually from eccrine glands located in the same region.
Sweating can serve both an excretory role (nitrogenous excretion, removal of excess water, and so forth) and a role in temperature regulation.
The hypothalamus senses core temperature directly, and also has input from temperature receptors in the skin and modifies the sweat output, along with other thermoregulatory processes.
The secretions of the apocrine sweat glands are thicker and more stick than the watery fluid of the eccrine sweat glands and contains fatty materials.
Sweat contains primarily water, but also salts and metabolic waste products—primarily sodium chloride, urea, lactic acid, and potassium ions (Blood et al.
Sweating (as well as perspiration) refers to the production, secretion, and evaporation of sweat.
Sweat serves an excretory function for releasing excess water and waste products.
Sweat contains water, sodium chloride, and small amounts of urea, lactic acid, and potassium salts, and is a much less concentrated fluid than blood plasma (Blood et al.