The facial sweat of a runner
ICD-10 R61 ICD-9 780.8
Perspiration (sweating, transpiration, or diaphoresis) is the production of a fluid consisting primarily of water as well as various dissolved solids (chiefly chlorides), that is excreted by the sweat glands in the skin of mammals. Sweat contains the chemicals or odorants 2-methylphenol (o-cresol) and 4-methylphenol (p-cresol), as well as a small amount of urea.
In humans, sweating is primarily a means of thermoregulation, although it has been proposed that components of male sweat can act as pheromonal cues. Trace amount of toxins are excreted through perspiration.
Evaporation of sweat from the skin surface has a cooling effect due to the latent heat of evaporation of water. Hence, in hot weather, or when the individual's muscles heat up due to exertion, more sweat is produced. Sweating is increased by nervousness and nausea and decreased by cold. 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. Primates and horses have armpits that sweat like those of humans. Although sweating is found in a wide variety of mammals, relatively few, such as humans and horses, produce large amounts of sweat in order to cool down.
A study has discovered that men, on average, start perspiring much more quickly than women, then twice as much when they are in the middle of exercising at the same relative intensity. When men and women exercise at the same absolute intensity there are no differences in sweating responses.
- Hypohidrosis is decreased sweating from whatever cause
- Hyperhidrosis is increased sweating from whatever cause
- Hidromeiosis is a reduction in sweating that is due to blockages of sweat glands in humid conditions.
Sweating allows the body to regulate its temperature. Sweating is controlled from a center in the preoptic and anterior regions of the brain's hypothalamus, where thermosensitive neurons are located. The heat-regulatory function of the hypothalamus is also affected by inputs from temperature receptors in the skin. High skin temperature reduces the hypothalamic set point for sweating and increases the gain of the hypothalamic feedback system in response to variations in core temperature. Overall, however, the sweating response to a rise in hypothalamic ('core') temperature is much larger than the response to the same increase in average skin temperature. The process of sweating decreases core temperature, whereas the process of evaporation decreases surface temperature.
There are two situations in which the nerves will stimulate the sweat glands, causing perspiration: during physical heat and during emotional stress. In general, emotionally induced sweating is restricted to palms, soles, armpits, and sometimes the forehead, while physical heat-induced sweating occurs throughout the body.
Sweat is not pure water; it always contains a small amount (0.2–1%) of solute. When a person moves from a cold climate to a hot climate, adaptive changes occur in the sweating mechanisms of the person. This process is referred to as acclimatisation: the maximum rate of sweating increases and its solute composition decreases. The volume of water lost in sweat daily is highly variable, ranging from 100 to 8,000 mL/day. The solute loss can be as much as 350 mmol/day (or 90 mmol/day acclimatised) of sodium under the most extreme conditions. In a cool climate and in the absence of exercise, sodium loss can be very low (less than 5 mmols/day). Sodium concentration in sweat is 30-65 mmol/l, depending on the degree of acclimatisation.
Sweat contains mainly water. It also contains minerals, lactate, and urea. Mineral composition varies with the individual, their acclimatisation to heat, exercise and sweating, the particular stress source (sauna, etc.), the duration of sweating, and the composition of minerals in the body. An indication of the minerals content is sodium (0.9 gram/liter), potassium (0.2 g/l), calcium (0.015 g/l), magnesium (0.0013 g/l). Also many other trace elements are excreted in sweat, again an indication of their concentration is (although measurements can vary fifteenfold) zinc (0.4 milligrams/liter), copper (0.3–0.8 mg/l), iron (1 mg/l), chromium (0.1 mg/l), nickel (0.05 mg/l), lead (0.05 mg/l). Probably many other less-abundant trace minerals leave the body through sweating with correspondingly lower concentrations. Some exogenous organic compounds make their way into sweat as exemplified by an unidentified odiferous "maple syrup" scented compound in several of the species in the mushroom genus Lactarius. In humans, sweat is hypoosmotic relative to plasma.
- ^ Mosher HH (1933). "Simultaneous Study of Constituents of Urine and Perspiration". The Journal of Biological Chemistry 99 (3): 781–790. http://www.jbc.org/cgi/reprint/99/3/781.pdf.
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- ^ "Women outshine men in sweat test". Sydney Morning Herald. 9 October 2010. http://www.smh.com.au/lifestyle/lifematters/women-outshine-men-in-sweat-test-20101008-16c0c.html. Retrieved 21 October 2010.
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- ^ Kameia, Tomoya; Tsudab, Takao; Kitagawab, Shinya; Naitoha, Ken; Nakashimaa, Koji; Ohhashi, Toshio (June 1998). "Physical stimuli and emotional stress-induced sweat secretions in the human palm and forehead". Analytica Chimica Acta 365 (1-3): 319–326. doi:10.1016/S0003-2670(97)00642-9.
- ^ "Sweat mineral-element responses during 7 h of exercise-heat stress," Int J Sport Nutr Exerc Metab 2007 Dec;17(6):574-82.
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- ^ Saraymen, Recep; Kılıç, Eser; Yazar, Süleyman (2004). "Sweat Copper, Zinc, Iron, Magnesium and Chromium Levels in National Wrestler". İnönü Üniversitesi Tıp Fakültesi Dergisi 11 (1): 7–10. http://mail.inonu.edu.tr/~tipdergi/include/getdoc.php?id=79&article=35&mode=pdf.
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Look at other dictionaries:
perspiration — [ pɛrspirasjɔ̃ ] n. f. • 1539; lat. perspiratio ♦ Physiol. Ensemble des échanges respiratoires qui se font par la peau. La perspiration est importante chez certains animaux (batraciens). Perspiration insensible : élimination de vapeur d eau par l … Encyclopédie Universelle
Perspiration — Per spi*ra tion, n. [Cf. F. perspiration.] 1. The act or process of perspiring. [1913 Webster] 2. That which is excreted through the skin; sweat. [1913 Webster] Note: A man of average weight throws off through the skin during 24 hours about 18… … The Collaborative International Dictionary of English
perspiration — 1610s, from Fr. perspiration (1560s), noun of action from perspirer perspire, from L. perspirare blow or breathe constantly, from per through + spirare to breathe, blow (see SPIRIT (Cf. spirit)). Applied to excretion of invisible moistures… … Etymology dictionary
Perspiration — steht für: Schwitzen, bei Tieren die Wasserabgabe über die Haut Hautatmung, bei Tieren der Austausch von Sauerstoff und Kohlendioxid über die Haut … Deutsch Wikipedia
Perspiration — (lat.), soviel wie Hautatmung, s. Atmung, S. 55. Die gasförmigen Ausscheidungen der Haut (Kohlensäure und Wasserdampf) werden als Perspiratio insensibilis der Schweißabsonderung (Perspiratio sensibilis) gegenübergestellt … Meyers Großes Konversations-Lexikon
Perspiration — Perspiratiōn (lat.), Hautausdünstung; perspiratōrish, die Ausdünstung befördernd; perspirieren, ausdünsten … Kleines Konversations-Lexikon
perspiration — ► NOUN 1) sweat. 2) the process of perspiring … English terms dictionary
perspiration — [pʉr΄spə rā′shən] n. [Fr] 1. the act of perspiring; sweating 2. salty moisture given off in perspiring; sweat … English World dictionary
perspiration — noun … OF PERSPIRATION ▪ bead, drop ▪ Great beads of perspiration trickled down his forehead. VERB + PERSPIRATION ▪ wipe ▪ He wiped the perspiration from his brow … Collocations dictionary
perspiration — /perr speuh ray sheuhn/, n. 1. a salty, watery fluid secreted by the sweat glands of the skin, esp. when very warm as a result of strenuous exertion; sweat. 2. the act or process of perspiring. [1605 15, in sense a breathing through ; 1620 30 for … Universalium