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Urine is a liquid
by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be consid ...
of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being
excreted Excretion is a process in which metabolic waste is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after lea ...
from the body through the urethra.
Cellular Cellular may refer to: *Cellular automaton, a model in discrete mathematics * Cell biology, the evaluation of cells work and more * ''Cellular'' (film), a 2004 movie *Cellular frequencies, assigned to networks operating in cellular RF bands *Cell ...
metabolism generates many
by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be consid ...
s that are rich in nitrogen and must be cleared from the bloodstream, such as urea, uric acid, and creatinine. These by-products are expelled from the body during urination, which is the primary method for excreting water-soluble chemicals from the body. A urinalysis can detect nitrogenous wastes of the
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
ian body. Urine plays an important role in the earth's
nitrogen cycle The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biologi ...
. In balanced ecosystems, urine fertilizes the soil and thus helps plants to grow. Therefore, urine can be used as a fertilizer. Some animals use it to mark their territories. Historically, aged or fermented urine (known as
lant Lant is aged urine. The term comes from Old English , which referred to urine. Collected urine was put aside to ferment until used for its chemical content in many pre-industrial processes, such as cleaning and production. History Because of ...
) was also used for gunpowder production, household cleaning, tanning of leather and dyeing of textiles. Human urine and
feces Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...
are collectively referred to as
human waste Human waste (or human excreta) refers to the waste products of the human digestive system, menses, and human metabolism including urine and faeces. As part of a sanitation system that is in place, human waste is collected, transported, treated a ...
or human excreta, and are managed via sanitation systems. Livestock urine and feces also require proper management if the livestock population density is high.


Physiology

Most animals have excretory systems for elimination of soluble toxic wastes. In humans, soluble wastes are excreted primarily by the urinary system and, to a lesser extent in terms of urea, removed by perspiration. The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The system produces urine by a process of
filtration Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter ...
, reabsorption, and tubular secretion. The kidneys extract the soluble wastes from the bloodstream, as well as excess water, sugars, and a variety of other compounds. The resulting urine contains high concentrations of urea and other substances, including toxins. Urine flows from the kidneys through the ureter, bladder, and finally the urethra before passing from the body.


Duration

Research looking at the duration of urination in a range of
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
species found that nine larger species urinated for 21 ± 13 seconds irrespective of body size. Smaller species, including rodents and bats, cannot produce steady streams of urine and instead urinate with a series of drops.


Characteristics


Quantity

Average urine production in adult humans is around 1.4 L of urine per person per day with a normal range of 0.6 to 2.6 L per person per day, produced in around 6 to 8 urinations per day depending on state of hydration, activity level, environmental factors, weight, and the individual's health. Text was copied from this source, which is available under
Creative Commons Attribution 4.0 International License
.
Producing too much or too little urine needs medical attention. Polyuria is a condition of excessive production of urine (> 2.5 L/day), oliguria when < 400 mL are produced, and anuria being < 100 mL per day.


Constituents

About 91-96% of urine consists of water. The remainder can be broadly characterized into inorganic salts, urea, organic compounds, and organic ammonium salts.Composition Of The Urine. (1872). ''The British Medical Journal'', ''1''(579), 133–133. http://www.jstor.org/stable/25231362 Urine also contains proteins, hormones, and a wide range of
metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...
s,Helmenstine, Anne Marie, Ph.D. (2020, August 26). What Is the Chemical Composition of Urine? Retrieved from https://www.thoughtco.com/the-chemical-composition-of-urine-603883 varying by what is introduced into the body. The total solids in urine are on average 59 g per day per person. Urea is the largest constituent of the solids, constituting more than 50% of the total. The daily volume and composition of urine varies per person based on the amount of physical exertion, environmental conditions, as well as water, salt, and protein intakes. In healthy persons, urine contains very little protein and an
excess Excess may refer to: * Angle excess, in spherical trigonometry * Insurance excess, similar to a deductible * Excess, in chemistry, a reagent that is not the limiting reagent * "Excess", a song by Tricky from the album '' Blowback'' * ''Excess'' ( ...
is suggestive of illness, as with sugar. Organic matter, in healthy persons, also is reported to at most 1.7 times more matter than minerals. However, any more than that is suggestive of illness. However, it is important to note that lesser amounts and concentrations of other compounds and ions are often present in urination of humans.


Color

Urine varies in appearance, depending principally upon a body's level of
hydration Hydration may refer to: * Hydrate, a substance that contains water * Hydration enthalpy, energy released through hydrating a substance * Hydration reaction, a chemical addition reaction where a hydroxyl group and proton are added to a compound * ...
, interactions with drugs, compounds and pigments or
dye A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...
s found in food, or diseases. Normally, urine is a transparent solution ranging from colorless to amber, but is usually a pale yellow. Usually urination color comes primarily from the presence of urobilin. Urobilin is a final waste product resulting from the breakdown of heme from hemoglobin during the destruction of aging blood cells. Colorless urine indicates over-hydration. Colorless urine in drug tests can suggest an attempt to avoid detection of illicit drugs in the bloodstream through over-hydration. * Dark yellow urine is often indicative of dehydration. * Yellowing may be caused by removal of excess
riboflavin Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in ...
from the bloodstream. * Certain medications such as rifampin and phenazopyridine can cause orange urine. * Bloody urine is termed hematuria, a symptom of a wide variety of medical conditions. * Dark orange to brown urine can be a symptom of
jaundice Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...
,
rhabdomyolysis Rhabdomyolysis (also called rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some of th ...
, or Gilbert's syndrome. * Black or dark-colored urine is referred to as melanuria and may be caused by a
melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...
or non-melanin acute intermittent porphyria. * Pinkish urine can result from the consumption of beets (
beeturia Beeturia is the passing of red or pink urine after eating beetroots or foods colored with beetroot extract or beetroot pigments. The color is caused by the excretion of betalain (betacyanin) pigments such as betanin. The coloring is highly varia ...
) * Greenish urine can result from the consumption of asparagus or foods, beverages with green pigments, or from a urinary tract infection. * Reddish or brown urine may be caused by porphyria (not to be confused with the harmless, temporary pink or reddish tint caused by
beeturia Beeturia is the passing of red or pink urine after eating beetroots or foods colored with beetroot extract or beetroot pigments. The color is caused by the excretion of betalain (betacyanin) pigments such as betanin. The coloring is highly varia ...
). * Blue urine can be caused by the ingestion of
methylene blue Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. Methylene blue is a thiazine dye. As a medication, it is mainly used to treat methemoglobinemia by converting the ferric iron in hemoglobin ...
(e.g., in medications) or foods or beverages with blue dyes. * Blue urine stains can be caused by blue diaper syndrome. * Purple urine may be due to purple urine bag syndrome. File:Dark urine due low fluid intake.jpg, Dark urine due to low fluid intake. File:HematuriaGross.jpg, Dark red urine due to blood ( hematuria). File:Choluria.svg, Dark red urine due to choluria. File:Pinkish urine beetroots 1.jpg, Pinkish urine due to consumption of beetroots. File:IMAG0466.jpg, Green urine during long term infusion of the sedative
propofol Propofol, marketed as Diprivan, among other names, is a short-acting medication that results in a decreased level of consciousness and a lack of memory for events. Its uses include the starting and maintenance of general anesthesia, sedation f ...
.


Odor

Sometime after leaving the body, urine may acquire a strong "fish-like" odor because of contamination with bacteria that break down urea into ammonia. This odor is not present in fresh urine of healthy individuals; its presence may be a sign of a urinary tract infection. The odor of normal human urine can reflect what has been consumed or specific diseases. For example, an individual with diabetes mellitus may present a sweetened urine odor. This can be due to kidney diseases as well, such as kidney stones. Additionally, the presence of amino acids in urine (diagnosed as
maple syrup urine disease Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder affecting branched-chain amino acids. It is one type of organic acidemia. The condition gets its name from the distinctive sweet odor of affected infants' urine and ear ...
) can cause it to smell of
maple syrup Maple syrup is a syrup made from the sap of maple trees. In cold climates, these trees store starch in their trunks and roots before winter; the starch is then converted to sugar that rises in the sap in late winter and early spring. Maple tree ...
. Eating asparagus can cause a strong odor reminiscent of the vegetable caused by the body's breakdown of
asparagusic acid Asparagusic acid is an organosulfur compound with the molecular formula C4H6O2S2 and IUPAC nomenclature of organic chemistry, systematically named 1,2-dithiolane-4-carboxylic acid. The molecule consists of a heterocyclic disulfide functional gr ...
. Likewise consumption of saffron,
alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...
, coffee, tuna fish, and onion can result in telltale scents. Particularly spicy foods can have a similar effect, as their compounds pass through the kidneys without being fully broken down before exiting the body.


pH

The pH normally is within the range of 5.5 to 7 with an average of 6.2. In persons with hyperuricosuria, acidic urine can contribute to the formation of
stones In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's o ...
of uric acid in the kidneys, ureters, or bladder. Urine pH can be monitored by a physician or at home. A diet which is high in protein from meat and dairy, as well as alcohol consumption can reduce urine pH, whilst potassium and organic acids, such as from diets high in fruit and vegetables, can increase the pH and make it more alkaline. Cranberries, popularly thought to decrease the pH of urine, have actually been shown not to acidify urine. Drugs that can decrease urine pH include ammonium chloride, chlorothiazide diuretics, and methenamine
mandelate Mandelic acid is an aromatic alpha hydroxy acid with the molecular formula C6H5CH(OH)CO2H. It is a white crystalline solid that is soluble in water and polar organic solvents. It is a useful precursor to various drugs. The molecule is chiral. Th ...
.


Density

Human urine has a specific gravity of 1.003–1.035.


Bacteria and pathogens

Urine is not sterile, not even in the bladder. In the urethra, epithelial cells lining the urethra are colonized by facultatively anaerobic Gram-negative rod and cocci bacteria. One study conducted found total of 116 bacterial isolates were found in 77 healthy humans (ages 5–11) and 39 cows, a considerable amount being pathogens. Pathogens identified and their percentages were: The study also states:


Examination for medical purposes

Many physicians in ancient history resorted to the inspection and examination of the urine of their patients.
Hermogenes Hermogenes is a Greek name (), meaning "born of Hermes". It may refer to: * Hermogenes (potter) (fl. c. 550 BC), Attic Greek potter * Hermogenes (philosopher) (fl. c. 400 BC), Greek * Hermogenes of Priene (fl. c. 200 BC), Greek architect * Hermog ...
wrote about the color and other attributes of urine as indicators of certain diseases. Abdul Malik Ibn Habib of Andalusia d.862 AD, mentions numerous reports of urine examination throughout the Umayyad empire. Diabetes mellitus got its name because the urine is plentiful and sweet. The name '' uroscopy'' refers to any visual examination of the urine, including
microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...
, although it often refers to the aforementioned prescientific or Proto-scientific forms of urine examination. Clinical urine tests today duly note the color, turbidity, and odor of urine but also include urinalysis, which chemically analyzes the urine and quantifies its constituents. A culture of the urine is performed when a urinary tract infection is suspected, as bacteriuria without symptoms doesn't require treatment. A microscopic examination of the urine may be helpful to identify organic or inorganic substrates and help in the diagnosis. The color and volume of urine can be reliable indicators of hydration level. Clear and copious urine is generally a sign of adequate hydration. Dark urine is a sign of dehydration. The exception occurs when diuretics are consumed, in which case urine can be clear and copious and the person still be dehydrated.


Uses


Source of medications

Urine contains proteins and other substances that are useful for medical therapy and are ingredients in many prescription drugs (e.g., Ureacin,
Urecholine Bethanechol is a parasympathomimetic choline carbamate that selectively stimulates muscarinic receptors without any effect on nicotinic receptors. Unlike acetylcholine, bethanechol is not hydrolyzed by cholinesterase and will therefore have a l ...
, Urowave). Urine from postmenopausal women is rich in gonadotropins that can yield
follicle stimulating hormone Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland and regulates the development, growth, pubertal maturation, an ...
and luteinizing hormone for fertility therapy. One such commercial product is Pergonal. Urine from pregnant women contains enough human chorionic gonadotropins for commercial extraction and purification to produce hCG medication. Pregnant mare urine is the source of estrogens, namely Premarin. Urine also contains
antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
, which can be used in diagnostic antibody tests for a range of pathogens, including HIV-1. Urine can also be used to produce urokinase, which is used clinically as a thrombolytic agent.


Fertilizer


Cleaning

Given that urea in urine breaks down into ammonia, urine has been used for cleaning. In pre-industrial times, urine was used – in the form of ''
lant Lant is aged urine. The term comes from Old English , which referred to urine. Collected urine was put aside to ferment until used for its chemical content in many pre-industrial processes, such as cleaning and production. History Because of ...
'' or aged urine – as a cleaning fluid. Urine was also used for whitening teeth in Ancient Rome.


Gunpowder

Urine was used before the development of a
chemical industry The chemical industry comprises the companies that produce industrial chemicals. Central to the modern world economy, it converts raw materials (oil, natural gas, air, water, metals, and minerals) into more than 70,000 different products. The ...
in the manufacture of gunpowder. Urine, a nitrogen source, was used to moisten straw or other organic material, which was kept moist and allowed to rot for several months to over a year. The resulting salts were washed from the heap with water, which was evaporated to allow collection of crude saltpeter crystals, that were usually refined before being used in making gunpowder.


Survival uses

The ''
US Army Field Manual United States Army Field Manuals are published by the United States Army's Army Publishing Directorate. As of 27 July 2007, some 542 field manuals were in use. They contain detailed information and how-tos for procedures important to soldiers ser ...
'' advises ''against'' drinking urine for survival. These guides explain that drinking urine tends to worsen rather than relieve dehydration due to the salts in it, and that urine should not be consumed in a survival situation, even when there is no other fluid available. In hot weather survival situations, where other sources of water are not available, soaking cloth (a shirt for example) in urine and putting it on the head can help cool the body. During World War I, Germans experimented with numerous poisonous gases as weapons. After the first German chlorine gas attacks, Allied troops were supplied with masks of cotton pads that had been soaked in urine. It was believed that the ammonia in the pad neutralized the chlorine. These pads were held over the face until the soldiers could escape from the poisonous fumes. Urban legend states that urine works well against jellyfish stings. This scenario has appeared many times in popular culture including in the ''
Friends ''Friends'' is an American television sitcom created by David Crane and Marta Kauffman, which aired on NBC from September 22, 1994, to May 6, 2004, lasting ten seasons. With an ensemble cast starring Jennifer Aniston, Courteney Cox, Lisa ...
'' episode "The One With the Jellyfish", an early episode of ''
Survivor Survivor(s) may refer to: Actual survivors * *Last survivors of historical events Arts, entertainment, and media Fictional entities * Survivors, characters in the 1997 ''KKnD'' video-game series * ''The Survivors'', or the ''New Survivors Found ...
'', as well as the films '' The Real Cancun'' (2003), '' The Heartbreak Kid'' (2007) and '' The Paperboy'' (2012). However, at best it is ineffective, and in some cases this treatment may make the injury worse.


Textiles

Urine has often been used as a mordant to help prepare textiles, especially wool, for dyeing. In the Scottish Highlands and Hebrides, the process of "
waulking Fulling, also known as felting, tucking or walking ( Scots: ''waukin'', hence often spelled waulking in Scottish English), is a step in woollen clothmaking which involves the cleansing of woven or knitted cloth (particularly wool) to elimin ...
" (fulling) woven wool is preceded by soaking in urine, preferably infantile.


Animal repellent

The urine of predator species is often used as a repellent against their prey species. Urine plays a role in
interspecific communication Interspecies communication is communication between different species of animals, plants, or microorganisms. Mutualism Cooperative interspecies communication implies sharing and understanding information between two or more species that work to ...
, since it contains semiochemicals that can act as kairomones.


History

The fermentation of urine by bacteria produces a solution of ammonia; hence fermented urine was used in Classical Antiquity to wash cloth and clothing, to remove hair from hides in preparation for tanning, to serve as a mordant in dying cloth, and to remove rust from iron. Ancient Romans used fermented human urine (in the form of
lant Lant is aged urine. The term comes from Old English , which referred to urine. Collected urine was put aside to ferment until used for its chemical content in many pre-industrial processes, such as cleaning and production. History Because of ...
) to cleanse grease stains from clothing. The emperor Nero instituted a tax ( la, vectigal urinae) on the urine industry, continued by his successor, Vespasian. The Latin saying ''
Pecunia non olet is a Latin saying that means "money does not stink". The phrase is ascribed to the Roman emperor Vespasian (ruled AD 69–79). History A tax on the disposal of urine was first imposed by Emperor Nero under the name of in the 1st century AD. ...
'' (money doesn't smell) is attributed to Vespasian – said to have been his reply to a complaint from his
son A son is a male offspring; a boy or a man in relation to his parents. The female counterpart is a daughter. From a biological perspective, a son constitutes a first degree relative. Social issues In pre-industrial societies and some current c ...
about the unpleasant nature of the tax. Vespasian's name is still attached to public urinals in France (''vespasiennes''), Italy (''vespasiani''), and Romania (''vespasiene''). Alchemists spent much time trying to extract gold from urine, which led to discoveries such as white phosphorus by German alchemist
Hennig Brand Hennig Brand (; c. 1630c. 1692 or c. 1710) was a German alchemist who lived and worked in Hamburg. In 1669, Brand accidentally discovered the chemical element phosphorus while searching for the "philosopher's stone", a substance which was believed ...
when distilling fermented urine in 1669. In 1773 the French chemist
Hilaire Rouelle Hilaire Marin Rouelle (15 February 1718 – 7 April 1779) was an 18th-century French chemist. Commonly cited as the 1773 discoverer of urea, he was not the first to do so. Dutch scientist Herman Boerhaave had discovered this chemical A chem ...
discovered the organic compound urea by boiling urine dry.


Language

The English word ''urine'' (, ) comes from the Latin ''urina'' (''-ae'', ''f''.), which is cognate with ancient words in various Indo-European languages that concern water, liquid, diving, rain, and urination (for example Sanskrit ''varṣati'' meaning ''"it rains"'' or ''vār'' meaning "water" and Greek ''ourein'' meaning "to urinate"). The onomatopoetic term ''piss'' predates the word urine however is now considered vulgar.Harper, D. (n.d.). Etymology of piss. Online Etymology Dictionary. Retrieved March 17, 2022, from https://www.etymonline.com/word/piss “piss,” ''Merriam-Webster.com Dictionary'', https://www.merriam-webster.com/dictionary/piss . Accessed 3/17/2022. ''Urinate'' was at first used mostly in medical contexts. ''Piss'' is also used in such colloquialisms as ''to piss off'', ''piss poor'', and the slang expression ''pissing down'' to mean heavy rain.
Euphemism A euphemism () is an innocuous word or expression used in place of one that is deemed offensive or suggests something unpleasant. Some euphemisms are intended to amuse, while others use bland, inoffensive terms for concepts that the user wishes ...
s and expressions used between parents and children (such as ''wee'', ''pee'', and many others) have long existed. ''
Lant Lant is aged urine. The term comes from Old English , which referred to urine. Collected urine was put aside to ferment until used for its chemical content in many pre-industrial processes, such as cleaning and production. History Because of ...
'' is a word for aged urine, originating from the
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...
word ''hland'' referring to urine in general.


See also

* Drinking urine (urophagia) * Ureotelic * Urine therapy *
Urolagnia Urolagnia (also urophilia, and, more colloquially, a golden shower or watersports) associates sexual excitement with the sight or thought of urine or urination, and may also refer to such behaviours or acts. It is a paraphilia. The term has o ...
, an attraction to urine


Notes


References


External links


Urinanalysis
at the University of Utah Eccles Health Sciences Library

at drugs.com {{Authority control Animal physiology Body fluids Sanitation