Perspiration
77538
225795405
2008-07-15T13:04:13Z
Bibikoff
4158786
{{Redirect|Sweat}}
[[Image:Amanda Françozo At The Runner Sports Fragment.jpg|thumb|Drops of sweat]]
'''Perspiration''' (also called '''sweating''' or sometimes [[transpiration]]) is the production of a fluid, consisting primarily of [[water]] as well as various dissolved solids (chiefly chlorides), that is excreted by the [[sweat gland]]s in the [[skin]] of [[mammal]]s.<ref name="perspiration">[http://www.jbc.org/cgi/reprint/99/3/781.pdf|SIMULTANEOUS STUDY OF CONSTITUENTS OF URINE AND PERSPIRATION"], H. H. MOSHER, ''The Journal of Biological Chemistry'' 16 November 1932</ref> Sweat also contains the chemicals or [[odorant]]s [[Cresol|2-methylphenol]] (''o''-cresol) and [[P-Cresol|4-methylphenol]] (''p''-cresol), as well as a small amount of [[urea]].
In [[human]]s, sweating is primarily a means of [[thermoregulation]], although it has been proposed that components of male sweat can act as [[pheromone|pheromonal]] cues <ref name="sweat">[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17287500&query_hl=1&itool=pubmed_docsum Smelling a single component of male sweat alters levels of cortisol in women"], C. Wyart et al., ''Journal of Neuroscience'', February 7, 2006</ref>. [[Evaporation]] of sweat from the skin surface has a cooling effect due to the [[latent heat]] of evaporation of water. Hence, in [[Temperature|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 [[dog]]s, 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 similarly to those of humans.
==Mechanism==
Sweating is controlled from a center in the preoptic and anterior regions of the [[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.
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 their sweating mechanisms. 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 & 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.
==Composition==
Sweat contains mainly [[water]]. It also contains minerals, as well as [[lactate]] and [[urea]]. Mineral composition will vary with the individual, the [[acclimatisation]] to [[heat]], [[exercise]] and [[sweating]], the particular [[stress]] source (exercise, [[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 gram/liter, [[calcium]] 0.015 gram/liter, [[magnesium]] 0.0013 gram/liter<ref>[http://www.ncbi.nlm.nih.gov/pubmed/18156662 Sweat mineral-element responses during 7 h of exer...[Int J Sport Nutr Exerc Metab. 2007] - PubMed Result<!-- Bot generated title -->]</ref>. Also many other [[trace elements]] are excreted in sweat, again an indication of their concentration is (although measurements can vary fifteenfold):
[[zinc]] (0.4 mg/l), [[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). <ref>Cohn JR, Emmett EA, The excretion of trace metals in human sweat., Ann Clin Lab Sci. 1978 Jul-Aug;8(4):270-5., http://www.ncbi.nlm.nih.gov/pubmed/686643 </ref> <ref>Saraymen et al., Sweat Copper, Zinc, Iron, Magnesium and Chomium levels in national westler. 1973</ref>. Probably many other less abundant trace minerals will leave the body through sweating with correspondingly lower concentrations. In humans sweat is hyposmotic relatively to the [[plasma]] <ref> BRS Physiology 4th edition, Linda S. Constanzo, page155</ref>.
==See also==
* [[Diaphoresis]]
* [[Hyperhidrosis]]
* [[Anhidrosis]]
* [[Hyponatremia]]
* [[Hyperthermia]]
* [[Body odor]]
* [[Hidradenitis suppurativa]]
* [[Pheromones]]
* [[Sweat gland]]
* [[Sweat therapy]]
== References==
<references />
== External links ==
*[http://www.berkeley.edu/news/media/releases/2007/02/06_sweat.shtml Male sweat boosts women's hormone levels] -- from [[UC Berkeley]], February 2007
*[http://www.sciencedaily.com/releases/2007/02/070207172019.htm The Effect of Male Sweat on Women's Hormone Levels] -- from Science Daily, February 2007
*K. Sato et al., [http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=2654204&dopt=Citation "Biology of sweat glands and their disorders"], ''Journal of the American Academy of Dermatology'', April 1989
== Further reading ==
* Ferner S, Koszmagk R, Lehmann A, Heilmann W., ''Z Erkr Atmungsorgane''. 1990;175(2):70-5. 'Reference values of Na(+) and Cl(-) concentrations in adult sweat'
* E. R. Nadel, R. W. Bullard, and J. A. Stolwijk, "Importance of skin temperature in the regulation of sweating", ''Journal of Applied Physiology'', Vol. 31, Issue 1, 80-87, July 1, 1971
{{commonscat|Perspiration}}
[[Category:Body fluids]]
[[Category:Exocrine system]]
[[Category:Animal physiology]]
[[Category:Reflexes]]
[[Category:Excretion]]
[[ar:تعرق]]
[[ay:Jump'i]]
[[az:Tər]]
[[da:Sved]]
[[de:Schwitzen]]
[[el:Ιδρώτας]]
[[es:Sudor]]
[[eo:Ŝvito]]
[[fr:Sueur]]
[[id:Keringat]]
[[is:Sviti]]
[[it:Sudorazione]]
[[he:זיעה]]
[[la:Sudor]]
[[lt:Prakaitavimas]]
[[nl:Zweten]]
[[ja:汗]]
[[pl:Pot]]
[[pt:Suor]]
[[ru:Пот]]
[[simple:Sweat]]
[[fi:Hiki]]
[[sv:Svettning]]
[[ta:வியர்வை]]
[[tr:Ter]]
[[yi:שוויצן]]
[[zh:汗液]]