Urine 3938382 225880356 2008-07-15T20:55:30Z Diligent Terrier 2499413 Reverted edits by [[Special:Contributions/98.233.152.107|98.233.152.107]] to last version by Winchelsea (using [[WP:HG|Huggle]]) {{Rewrite|Lack of structure, references, formality and data}} {{Expert-subject|Medicine}} {{weasel}} {{Otheruses4|the urine of animals generally|urine produced specifically by the human body|Human urine}} {{Distinguish|Uren}} {{wiktionarypar|urine}} '''Urine''' is an aqueous solution of electrolytes and metabolites excreted by [[mammal]]s, [[bird]]s, [[reptile]]s, [[fish]] and [[amphibian]]s. Although urine is excreted as a paste (uric acid) by most birds, it is commonly excreted as a fluid varying in color from clear, when dilute, to a dark amber, when concentrated. Urine is produced by the [[kidney]]s, and plays a vital role in maintaining [[homeostasis]] by removing excess water, electrolytes such as [[sodium]], [[chloride]], [[potassium]], and [[calcium]] ions, [[urea]] and other metabolites from the blood. Urine excreted by healthy kidneys is [[sterile]]. The production of urine is called [[diuresis]]. Urine samples can be taken by your doctor to check for symptoms of disease. ==Composition== ===Water=== The main constituent of urine is water. All vertebrates must carefully maintain the volume of fluid in their [[extracellular]] space in order to prevent fluid [[water intoxication|overload]] or [[dehydration]]. Some water is inevitably lost during solute excretion, and represents an unavoidable fluid loss. However, the majority of water excreted in the urine is lost to prevent fluid overload. Different animals have different renal physiologies depending on their need to retain water. [[Freshwater]] fish, for example, produce very large amounts of very dilute urine, whereas desert-dwelling animals such as the [[meerkat]] have very effective renal systems, allowing them to conserve water by producing small amounts of extremely concentrated urine. By comparison, even the most concentrated [[human urine]] is relatively dilute. The excretion of water is called aquaresis. ===Electrolytes=== Along with volume regulation, urine regulates the [[osmolarity]] of an animal's internal space. The concentration of ions in the blood and extra-cellular fluid must stay within a fairly tight range to maintain health and avoid dehydration. Although some ions are lost to normal bodily function (such as sweating), most animals have a large surplus of ions in their diets and must excrete them. Most humans, for example, ingest many more [[sodium]] and [[chloride]] ions than they need in the form of [salt] - it is secretion of these surplus ions which makes urine taste salty. ===Nitrogen=== Urine production and excretion is a vertebrate's primary method for removal of [[nitrogen]]. This is a waste product, produced in the form of ammonia by the liver. Excess nitrogen is found in the diet, and released into the blood during the [[deamination]] of [[amino acids]] in protein metabolism. In fish, where water conservation is not an issue, ammonia is excreted in dilute urine. However, at higher concentrations it is toxic, and so in mammals' urine, this mainly is in the form of [[urea]], produced from ammonia in the [[liver]]. Birds generally excrete [[uric acid]] as a paste, to further conserve water. ===Acid=== The kidneys play a vital role in regulating body pH, preventing [[acidosis]] or [[alkalosis]] by excreting excess [[hydrogen ions]] or [[bicarbonate ions]] as required. When it leaves the body, urine is usually around [[pH]] 6, though it may be as low as 4.5 or as high as 8.2. As [[urea]]—the compound which accounts for 75–90% of the [[nitrogen]] in urine—begins to decay, [[hydroxide]] ions form, raising the pH as high as 9–9.3. The decay of urea into carbon dioxide is catalyzed by [[urease]]: [[Urea|(NH<sub>2</sub>)<sub>2</sub>CO]] + H<sub>2</sub>O → [[carbon dioxide|CO<sub>2</sub>]] + 2[[ammonia|NH<sub>3</sub>]] ===Metabolites=== Animals ingest a wide variety of compounds daily. Not least are humans, who consume an incredible array of natural and artificial chemicals in the form of food, drink and pharmaceutical products. With the exception of [[vitamins]], [[minerals]] and other micro-nutrients such as [[essential fatty acids]], none of these are needed or desirable within the body. All are either metabolised by the liver, excreted in bile or filtered from the blood by the kidneys, and excreted in urine. ===Dissolved heavy metals=== Studies of urine in organic cattle farms in Sweden in 1999 and 2002 yielded the following concentrations of [[heavy metals]] (all in μg/kg wet weight):<ref name=SEI>[http://www.ecosanres.org/pdf_files/ESR_Publications_2004/ESR2web.pdf Guidelines_Urine_Faeces.indd<!-- Bot generated title -->]</ref> *[[Copper]]: 67 *[[Zinc]]: 30 *[[Chromium]]: 5 *[[Lead]]: 1 *[[Cadmium]]: 0 ===Glucose=== Glucose is constantly lost from the blood into the filtrate at the kidneys - however, active reuptake in the [[proximal tubule]] usually prevents any being excreted. This is desirable, as glucose is a valuable source of energy, not a waste product. However, in [[hyperglycemia]] - most commonly arising from [[diabetes mellitus]] in humans - the tubular limit on glucose reabsorbtion may be breached, in which case some glucose will be lost in the urine. ===Bacteria=== Urine excreted by healthy kidneys is [[sterile]]. When it leaves the body, however, the urine can pick up bacteria from the surrounding skin, which would contaminate it. ==Characteristics== {{main|Human urine}} ===Color=== Urine is normally yellow because it contains [[urobilin]]. It can also be colourless if an excessive amount of water is consumed. ==Uses== ===Diagnostic tests=== {{Main|Urinalysis}} Testing urine for its constituents is a cost-effective and non-invasive means of assessing the internal situation of an animal. It is commonly used to test for pregnancy, by measuring levels of hormones excreted. Urinalysis can also be used to test for the metabolites of illegal drugs, if substance abuse is suspected. It is also an invaluable first-line investigation in clinical medicine, where pH, glucose, protein, [[white blood cell]], bacteria and blood content can all be tested to aid in making a diagnosis. ===Fertilizer=== Urine has been and is used extensively as [[fertilizer]]. Its high nitrogen content allows increased amino acid synthesis by plants. During WWII, Japanese farmers used urine collected in so-called "honeypots" as cheap fertilizer for their crops. ===Animal repellent=== Taking advantage of the scents of male animals' urine, some companies sell animal urine, usually coyote or fox, to cities and other organizations to repel those animals by essentially "marking their territory". The scents of carnivore urine ([[bobcat]], [[mountain lion]], and [[wolf]], in addition to coyote and fox) are also sold to the public in pelletized form to repel [[garden]] browsing by [[herbivores]] such as [[squirrels]] and [[rabbits]], as well as deterring domestic or feral cats from marking territory, or catching [[birds]], in gardens. When the pellets are sprinkled on a target area, the intruding animal will instinctively recognize the territorial urinary scent of its predators and avoid the area. ===Munitions=== In historical times, urine was collected and used in the manufacture of [[gunpowder]]. Stale urine was filtered through a barrel full of straw and allowed to continue to sour for a year or more. After this period of time, water was used to wash the resulting chemical [[salts]] from the straw. This slurry was filtered through wood ashes and allowed to dry in the sun. [[Potassium nitrate|Saltpeter]] crystals were then collected and added to [[sulfur]] and [[charcoal]] to create [[black powder]].[http://www.foxfire.org/foxfire5.aspx][http://en.wikipedia.org/wiki/Potassium_nitrate] ===Textiles=== Urine has often been used as a [[mordant]] to help prepare textiles, especially wool, for dyeing. Urine was used for dyes such as [[indigo]] where the urea in the urine reacted with the insoluble dye to form a soluble solution. ===Hormone replacement therapy=== Steroid hormones extracted from the urine of pregnant [[Mare (horse)|mares]]{{Fact|date=April 2008}} are used in a drug sold under the trade name [[Premarin]] (a [[neologism]] derived from 'pregnant mare urine'). The drug, manufactured and sold by [[Wyeth]], is an estrogen replacement therapy used in the treatment of [[menopause]] symptoms. === Antiseptic === Human and animal urine has historically been used as antiseptic. ==References== {{Reflist}} {{Refimprove|date=January 2008}} ==See also== *[[Kidneys]] *[[Human urine]] *[[Renal physiology]] *[[Diuresis]] *[[Diuretics]] *[[Urine-indicator dye]] {{renal physiology}} [[Category:Body fluids]] [[Category:Urine]] {{Link FA|de}} [[af:Urine]] [[am:ሽንት]] [[ar:بول]] [[ay:Chhuxu]] [[cs:Moč]] [[da:Urin]] [[de:Urin]] [[et:Uriin]] [[es:Orina]] [[eo:Urino]] [[fa:ادرار]] [[fr:Urine]] [[gd:Mùn]] [[ko:오줌]] [[id:Urin]] [[it:Urina]] [[he:שתן]] [[ku:Mîz]] [[la:Urina]] [[lt:Šlapimas]] [[hu:Vizelet]] [[ml:മൂത്രം]] [[nl:Urine]] [[ja:尿]] [[no:Urin]] [[nn:Urin]] [[pl:Mocz]] [[pt:Urina]] [[qu:Ispay]] [[ru:Моча]] [[simple:Urine]] [[sk:Moč]] [[fi:Virtsa]] [[sv:Urin]] [[ta:சிறுநீர்]] [[tr:İdrar]] [[yi:יורינע]] [[zh:尿]]