The Composition Of Human Sweat

By Author: Sulamita Berrezi
Total Articles: 115
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The composition of human sweat is highly variable, both between individuals and within an individual over time. However, sodium and chloride are the major electrolytes lost in sweat, with other ions being present in smaller amounts relative to the whole body status. The sweat electrolyte composition of an individual seems to be related primarily to sweat rate but can be influenced by training status, extent of heat acclimation, and diet. However, the range of values for sweat electrolyte composition reported in the literature probably reflects not only the interindividual differences but also differences in the methodology used for collection of the sweat. This last factor may be the result of errors caused by contamination or incomplete collection of the sample, or it may reflect a real difference induced by the collection procedure. Due to the secretion and reabsorption process involved in sweat production within the sweat gland and duct, sweat composition is influenced by sweat rate, at least within single ducts, such that a reduction in rate allows for greater reabsorption of certain electrolytes (Naþ, Cl, but not Kþ) ...
... from the duct resulting in a lower concentration in the final sweat produced. There also appear to be regional variations in sweat composition, as evidenced by the different values obtained when the composition of sweat obtained from different parts of the body is compared, and the values obtained by regional collection also differ from those obtained by the whole body washdown technique.In healthy individuals, water is the largest single component of the body. Although water balance is regulated around a range of volumes rather than a finite set point, its homeostasis is critical for virtually all physiological functions. To further ensure proper regulation of physiological and metabolic functions, the composition of the individual body water compartments must also be regulated. Humans continually lose water through the renal system, gastrointestinal system, skin, and respiratory tract, and this water must be replaced. Thirst is implicated in our water intake, but behavioral habits also have an important influence on drinking. When exercise is undertaken or when an individual is exposed to a warm environment, the additional heat load is lost largely due to sweating and this can increase greatly the individual's daily water loss and therefore the amount that must be consumed. Sweat rates on the order of 2 to 3 l per hour can be reached and maintained by some individuals for a number of hours and it is not impossible for total losses to be as much as 10 l in a day. These losses must of course be replaced and when they are so extreme, the majority must be met from fluid consumption rather than food ingestion. A variety of drink types and flavors are likely to be favored by individuals who have extreme losses to replace. Sports drinks have an importance role in this recovery when no food is ingested by their contribution to sweat electrolyte loss replacement which is crucial for retention of the ingested water.