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&#93; - 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]]