The urine ( latin urina ), also urine called, is a liquid to pasty precipitation product of the vertebrates . It arises in the kidneys and is carried out via the urinary tract . The excretion of urine is used to regulate the fluid and electrolyte balance and to remove metabolic degradation products ( metabolites ), in particular the nitrogen compounds formed during the breakdown of proteins and nucleotides . The totality of the metabolites detectable in the urine is called the urine metabolome .
Natural urination is called micturition in medicine . In the general language, there are numerous synonyms in addition to “urinate” and “urinate”.
Urine comes from the Latin urina , which, like the synonymous ancient Greek οὖρον oúron, originally meant “water” (cf. Latin urinari , “to submerge” and urinator , “diver”, and Sanskrit vāri , “water”).
After the medical school of Salerno developed the urine test as a diagnostic method in the High Middle Ages, the Latin word was transferred from the language of doctors to many European languages. In Old French , urine was already documented in the 12th century, in English only around 1325, urinal meaning "vessel for urine examinations", however, as early as 1275. In German, the term was first used in the 15th century, i.e. in early New High German . Since then, the word has increasingly replaced the older German terms.
The older word Harn has been attested and used unchanged since Old High German , but only in High German . Other regional names are taboo and are now considered offensive. These include the Upper German expressions Brunz (cf. also Brunnen as a euphemism in the 16th century for Harn ) and Seich , the originally Low German word piss or pee in children's language , the word ships used in Austria and the word Lulu ( emphasized on the second syllable) ( metonymically also for the corresponding organ of excretion).
Humans and other mammals
Urine initially arises in the kidneys as an ultrafiltrate from the blood plasma . Blood flows through the kidney corpuscles (corpuscula renalia) . Water and dissolved substances with a diameter of less than 4.4 nanometers (including ions and small uncharged proteins ) are filtered like in a sieve and enter the adjoining tubular system (kidney tubules) of the nephron , the functional subunit of the kidneys. The larger particles remain in the bloodstream . The resulting liquid is called primary urine and, in addition to the substances intended for excretion, also contains substances that are important for the body, such as glucose (grape sugar), amino acids and electrolytes . An adult produces between 180 and 200 liters of primary urine daily.
In the subsequent tubules and collecting tubes , the reusable constituents and around 99 percent of the water are recovered from the primary urine. The remaining terminal urine , of which a healthy adult produces around 1 to 1.5 liters per day (i.e. around 30 ml / h per kidney), finally flows over the renal pelvis and through the ureters into the urinary bladder . There the terminal urine (= urine) is collected and then excreted through the urethra .
The process of producing and excreting urine by the kidneys is called diuresis . This can be influenced with various medical measures. Diuretics are used to increase the urine volume in kidney and heart diseases and thus secondarily reduce the blood volume, as this in turn results in a reduced load on the heart (circulation, preload of the heart ventricles). A forced diuresis is z. B. used to remove toxic water-soluble substances from the organism through increased excretion. Some substances, such as caffeine or ethanol (drinking alcohol), also have a diuretic effect because they inhibit the formation of the hormone ADH (antidiuretic hormone) , which otherwise causes the kidneys to reabsorb water from the urine.
- In humans , a urine production of> 2.5 l / day is called polyuria , a low (<100 ml / day) or no urine output is called anuria . An amount of <400–500 ml / day is called oliguria .
- The term pollakiuria means the above-average frequency of emptying the bladder with only small amounts of urine.
- Various diseases of various causes are referred to as diabetes , which in turn lead to an increased flow of urine.
With regard to the collection of urine for a medical examination, different terms are distinguished from one another. In addition to the urine obtained by catheterization or suprapubic bladder puncture , these are various forms of urine obtained by simple urination. The following are timed:
- first morning urine,
- second morning urine,
- postprandial urine (usually two hours after a meal),
- Collection urine (usually as 24-hour urine).
A bladder emptying that is not determined by the time of day is called spontaneous urine .
Urine is used to regulate the fluid balance and to dispose of urea , uric acid and other metabolic end products. A healthy adult human excretes about 20 grams of urea. Urine also contains small amounts of sugar ( glucose ). An increased level of glucose in the urine indicates diabetes mellitus . The concentration of proteins is normally less than 2 to 8 mg per 100 ml, the maximum excretion is 100 to 150 mg daily, but on average 40 to 80 mg. Increased protein excretion is called proteinuria . The proteins are also responsible for the formation of foam on the urine. An unusually strong foam formation is therefore also an indication of nephropathy .
The pH of urine is a normal diet from 4.6 to 7.5, so rather in the acidic range. A single pH value measurement of the urine is only of limited informative value, since the pH value is subject to strong fluctuations on a daily basis. Protein-rich nutrition shifts the pH value towards acidic, while vegetables cause a shift into the alkaline environment.
The density is between 1015 and 1025 g / l. Under extreme conditions (such as extremely high fluid intake or on the other hand dehydration ) it can fluctuate between 1001 and 1040 g / l. Dissolved proteins or glucose can increase the density of urine. The osmolarity of urine is typically between 600 and 900 mosmol / l. Urine is then hyperosmotic in relation to blood plasma (290–300 mosmol / l), that is, the concentration of dissolved substances is higher than in blood plasma. The osmolarity, however, can vary between 50 and 1200 mosmol / l depending primarily on fluid intake and fluid losses (i.e., urine can be hypo-, iso- or hyperosmotic with respect to blood plasma).
Contrary to the widespread opinion that urine in healthy people is germ-free in the bladder, it already contains a large number of different bacteria there . Since the lower urethra is not germ-free, urine contains up to 10,000 germs per milliliter when it emerges.
Fresh urine smells like broth, while stale urine takes on the pungent odor of ammonia due to bacterial conversion processes . The urea is enzymatically ( urease ) converted into ammonia and carbon dioxide and the originally neutral to acidic urine becomes basic (pH value approx. 9–9.2). In the case of a severe metabolic imbalance in the context of diabetes mellitus , the urine can smell of acetone ; this is caused by ketoacidosis ( keto bodies in the blood). Even with acute illnesses (infections, fever) and after consuming certain foods, the urine can have an atypical odor.
Almost half of all people have a characteristic urine odor after consuming asparagus. It is due to the breakdown of certain ingredients in asparagus such as aspartic acid to S-methyl thioacrylate , to its methanethiol addition product S-methyl-3- (methylthio) thiopropionate and others. The ability to degrade is dominantly inherited .
The urine of pregnant women contains human chorionic gonadotropin (hCG), a hormone produced in the placenta that is responsible for maintaining pregnancy. This fact is used in the pregnancy test , which shows a change in color if hCG is present.
The yellow color of urine is caused by so-called Urochrome as the bilirubin -Abbauprodukte stercobilin and Urobilin resulting from the degradation of hemoglobin caused or blood pigment. The color intensity depends on the concentration of urochromes in the urine. Hypertonic (increased concentration of dissolved substances) urine is yellow or - at higher concentrations, for example as a result of dehydration - yellow-orange, while less concentrated (hypotonic urine) is light yellow to colorless.
In addition, if the person has consumed more carotenes or betanine (in beetroot ), the urine of some people may briefly turn red without blood getting into the urine through a wound or inflammation . Whether this is genetically inherited is unknown.
If the urine is saturated, then when it cools down, urates precipitate and become brick-red or dark yellow in color. When heated, it disappears again.
Dark orange or brown colored urine can be an indication of bilirubinuria and therefore jaundice ( jaundice ) or Meulengracht's disease . A black color of the urine is called melanuria . This contains melanogen , which oxidizes to melanin in the air . Melanuria can occur in the presence of melanoma . Black or dark urine is also found in alkaptonuria . In this case, homogenate is excreted in the urine due to a defect or lack of the enzyme homogenate dioxygenase . This darkens after contact with the air. Some medications can also cause urine to change color.
Simple excretory organs corresponding to the kidneys are already found in invertebrates . The excretion products of the proto- and meta nephridia as well as the Malpighian vessels are mostly also referred to as urine.
Also amphibians have opisthonephros without Henle loops and therefore can not produce hyperosmolar urine. In tadpoles, nitrogen is excreted via ammonia . After metamorphosis , it occurs via urea , in desert-dwelling amphibians and maci frogs via uric acid ( uricotelia ). The urine is released into the cloaca , which is connected to the urinary bladder via a short connecting duct. The urine stored there serves primarily as a water reservoir in amphibians. The constant loss of water through the skin can be compensated within certain limits by reabsorbing water from the urine.
The excretory organ of the fish is a modified primitive kidney , opisthonephros called. In mammals, the urnal kidney occurs only temporarily in the embryo . The nephron of the fish does not have a Henle loop, which is needed to concentrate the urine. Therefore, they cannot produce hyperosmolar urine (greater concentration of dissolved substances than in blood plasma). Some fish species ( e.g. pipefish , monkfish , Antarctic cod ) do not even have kidney corpuscles (aglomerular kidneys); urine is not produced by ultrafiltration, but by secretion and diffusion processes in the kidney tubules.
The function and composition of the urine depends on the habitat. In freshwater fish, a lot of urine is produced and its main purpose is to eliminate excess water. Electrolytes are never found in excess in freshwater fish; on the contrary, monovalent ions are actively absorbed via the epithelium of the gills . In the case of marine fish, on the other hand, the situation is reversed. They produce little urine, which is iso-osmotic compared to the blood. Because they live in salt water, they always have an excess of electrolytes, but they are not eliminated via the urine, but via the rectal glands ( cartilaginous fish ) or the epithelium of the gills ( bony fish ). In marine fish, the urine is not used for osmoregulation , but only for the excretion of divalent ions (such as Mg 2+ ) and excess nitrogen. Interesting are the conditions in migratory fish ( anadromous and catadromous fish), which spend part of their life in fresh water and the other part in salt water. The direction of the electrolyte exchange in the gills can be switched via hormones : cortisol releases monovalent ions to adapt to salt water, and prolactin triggers their uptake to adapt to fresh water.
In bony fish, the nitrogen compounds are mostly excreted as ammonia ( ammoniotelia ) directly via the gills, in some other fish, especially in cartilaginous fish , also as urea ( ureotelia ). In some cases nitrogen is also stored in the scales as guanine , which gives them their metallic sheen.
A urinary bladder and urethra are missing in some fish, the ureters open into the rectum, the urethra with its own porus, or (rarely) into a cloaca, etc.
Like all amniotes, reptiles have a posterior kidney (metanephros) . In contrast to birds and mammals, the nephrons do not have a loop of Henle and therefore cannot produce concentrated urine in the kidney. The amount of urine produced in reptiles is low (0.2 to 5.7 ml per kg body mass and hour). As in amphibians, the ureters flow into the cloaca. In lizards and turtles, a short passage leads from the cloaca into the urinary bladder (urinary bag), in which the urine can be stored. Snakes do not have a urinary bladder.
The urine of turtles is liquid. In the other reptiles, it is thickened in the rectum by water reabsorption and is therefore mushy to pasty. Excess nitrogen is excreted in the form of uric acid or guanine . The urine of reptiles is of secondary importance for the excretion of excess electrolytes, an excess of salt is balanced out via various head glands: orbital gland (sea turtles, on the eye), sublingual or premaxillary glands ( snakes), tongue glands ( crocodiles ), nasal glands (lizards).
The posterior kidney of birds stands between that of reptiles and mammals, since in addition to nephrons of the reptile type (without Henle's loop) there are also nephrons of the mammalian type, so that birds are capable of producing hyperosmolar urine. The urine is released through the left and right ureters into the middle section (urodeum) of the cloaca ; all birds lack a urinary bladder.
As in reptiles, excess nitrogen is excreted in the form of uric acid or guanine . The urine reaches the rectum via negative peristalsis , where water is withdrawn from it. The urine in birds is therefore pasty (light) and uric acid crystals precipitate, which are excreted together with the faeces (darker). The nitrogen-rich droppings of birds ( guano ) are also used as fertilizer . In birds with developed caecum ( e.g. chicken ) the concentrated urine can also be transported back into the caecum and serves as a source of nitrogen for the intestinal flora there . Excess electrolytes (table salt) are excreted not only in the urine of birds, but (as in lizards) also through the nasal gland , a mechanism that is important for maintaining osmolarity , especially in marine birds.
The urine examination , also called uroscopy or urine examination (using a urine glass ), is one of the oldest medical examinations. It allows conclusions to be drawn about the condition and functionality of the kidneys and bladder , for example in the case of renal insufficiency and bladder infection . While in the past the examination was carried out by describing the observations (color, cloudiness, deposits from the bladder drainage , etc.), the smell and the taste (this is where the diagnosis of diabetes mellitus comes from , since mellitus means "honey-sweet" in Latin ), nowadays the Initial examination primarily performed with the help of urine test strips. This allows you to collect several important findings simultaneously and within a few minutes. A color change can be used to approximately determine the content of proteins , glucose , ketones , bilirubin , urobilinogen , urobilin and the pH value. The urine is also tested for the presence of blood and inflammatory cells. The compilation of these results is called the urine status.
With the help of the urine status, early symptoms of three major disease groups can be recognized:
- Diseases of the kidneys and urinary tract ( kidney stones , kidney tumors , inflammation, ...)
- Carbohydrate metabolism disorders ( diabetes mellitus )
- Liver and hemolytic diseases.
A qualitative urine test shows whether a substance is present in the urine or not, while a quantitative test shows the exact amount of the substance tested. A semiquantitative test shows roughly how much of a substance is present in the urine.
A healthy person's urine should not contain proteins , nitrite , ketones, or blood components such as hemoglobin . If there are substances that are not normally found in the urine, or if the concentrations are changed, this can indicate metabolic diseases such as diabetes.
If fresh morning urine is centrifuged and then viewed under a microscope (examination of the urine sediment ), various solid components are visible. These include, for example, crystals of uric acid , calcium sulfate and calcium oxalate . Crystallized tyrosine or bilirubin , on the other hand, are signs of illness. In addition to the crystallized substances, cellular components can also be found under the microscope. These can indicate tumors of the kidneys and the lower urinary tract.
Using special detection tests, the intake of medication, poisons, drugs or doping substances can be detected in the urine. However, these examinations, which are used for example in addiction therapy, can be falsified by various additives such as bleach , soap or table salt . During pregnancy test is human chorionic gonadotropin (hCG) detected.
If various diseases are suspected, specific substances can be determined in the urine for this purpose. The 24-hour collection urine is usually used for this. When pheochromocytoma has one catecholamines after and their degradation products. The previous test for vanillin-mandelic acid is out of date due to insufficient specificity .
The amount of urine excreted is a crucial value in the fluid balance, in which the absorption of fluids is compared with the excretion (urine, sweat, perspiratio invisibilis ).
The mid- stream urine of the morning urine is preferred for examinations , as this contains the substances it contains in greater concentration than that obtained during the day. After an initial cleaning and, if necessary, disinfection of the glans in men or the genital area in women, the first stream of urine is discarded. Only the following parts are collected and used for the investigation. This reduces additions from impurities in the outer sections of the urethra that can falsify the result. In female test persons, obtaining unadulterated midstream urine is made significantly more difficult by the anatomy of the vulva and the secretions of the genitals.
Three glasses sample
A similar method is the three-glass test . The first jet and the central jet are collected in separate vessels. After a light prostate massage, the third glass is filled with urine mixed with prostate secretion. This allows a rough localization of bleeding sources, for example. The contents of the first glass represent the urethra, the second glass the urinary bladder and the third the prostate.
Other collection types
For specific questions, the urine can also be obtained via a catheter or by direct puncture of the bladder through the abdominal wall ( suprapubic bladder puncture ). This is usually free of germs from the area or the urethra. For some examinations, it is necessary to collect urine for 24 hours. This is usually the case when analyzing hormones and their breakdown products, such as B. vanillin-mandelic acid , homovanillic acid or 5-hydroxyindole acetic acid for the diagnosis of pheochromocytoma , neuroblastoma or carcinoid syndrome .
If mineral salts (e.g. calcium carbonate , calcium phosphate or calcium oxalate ) dissolved in the urine are precipitated , small crystals can initially form, which gradually combine to form larger structures. These structures, known as urinary or kidney stones , can accumulate in either the kidneys , ureters, or bladder and cause severe pain ( colic ). In most cases (around 80%), they go away on their own after the administration of anticonvulsant or pain relievers with the help of increased amounts of water and physical exercise. An intervention (sometimes only endoscopic ) is required less often and treatment by means of shock wave destruction ( extracorporeal shock wave lithotripsy ) is only necessary in extreme cases .
Use of urine
As a cleaning agent
Urine, especially “rotten” urine, has been used as a cleaning agent for thousands of years . In Rome, for example, amphora-like urinals were set up on busy streets to collect the urine required by the washers. Emperor Vespasian then levied a special urine tax. When his son Titus accused him of deriving monetary benefit from such a smelly affair, he is said to have held a coin in front of his nose and replied “ Pecunia non olet ” (“Money doesn't stink”).
Gefaulter urine was not until the 20th century the wool grease removal (scouring) freshly shorn sheep wool and fulling used by wool cloth, further in the tanning trade and for the pickling of copper covered roofs ( patina ) .
As a coloring agent
Urine is and was also of great importance for the dyeing trade. Indian yellow (magnesium euxanthate, a magnesium salt of euxanthic acid , empirical formula C 19 H 16 O 11 Mg · 5 H 2 O) was obtained from the urine of Indian cows that were fed exclusively with mango leaves . Its production has been known in India since the 15th century. The dye made its way to Europe in the 18th century. However, since the beginning of the twentieth century, this manufacturing method has lost its importance due to animal welfare concerns. In addition, human urine was used to produce indigo blue . For this purpose, the leaves of the woad were fermented with urine in buckets. The dyeing of textiles with urine and indigo is called vat dyeing . The reducing effect of urine is used to make indigo soluble and so bring the dye into the fiber.
As a plant nutrient
Due to the content of nitrogen compounds (especially urea , uric acid and creatinine in mammals including humans ), phosphates , potassium and calcium salts and the like. a. m. urine can serve as a supplier of plant nutrients . This salary is i. d. Usually so high that plants can be damaged or even caused to die by watering them with undiluted urine, they "burn". Diluted, e.g. For example, with eight to ten times the amount of water, urine is a strong growth-promoting fertilizer . In areas with very little rainfall , the salt content of the urine , which varies depending on the diet, can lead to salinisation of the soil.
As drinking water
Urine can be processed into drinking water through a special distillation filter system in order to counteract dehydration . Such a filter system is used, for example, on the International Space Station (ISS) in order to be able to supply the astronauts in space with sufficient drinking water and to save additional catering flights.
The distillation of urine in arid regions can also be an important survival strategy in terms of bushcrafting , provided there are no other water sources. However, urine that is not distilled or filtered incorrectly is not suitable as a drinking water substitute. It damages the kidneys and increases thirst. The urine can be desalinated by boiling or solar desalination . Activated carbon , for example, can be used as a pollutant filter . UV lamps , cleaning tablets and sieves, on the other hand, cannot hold back the small pollutants. Since in most cases not all pollutants are retained with simple self-made filters, there is a high health risk for laypeople.
In medicine, urine and substances obtained from urine have been used in a variety of ways. Urine was used as an effective wound disinfectant in war and disaster cases. Around 1500, the East Swabian surgeon Jörg zu Pforzen recommended a powder made from salt and the sediment of boys' urine to treat pannus (overgrowth of the cornea ). Today gonadotropins can be obtained from the urine of postmenopausal women , which can be used for the treatment of fertility disorders.
In the area of alternative medicine, " self-urine therapy " is used. The ability to heal various diseases is ascribed to one's own (morning) urine. Through drinking, external application or injection, diseases such as asthma , neurodermatitis or cellulite and others are supposed to be cured or at least alleviated. In Germany, among others, Carmen Thomas pleaded in her book A very special juice - urine to drink one's own urine . There is no evidence of a positive effect of self-urine therapy.
The Arab tradition knows the use of camel urine as a medicine. This goes back to a hadith by the Prophet Mohammed. More recently, researchers in Arabia have claimed camel urine to reduce cancer. In July 2015, the WHO warned against drinking camel urine because it could result in infection with MERS .
Since pathogenic prions - incorrectly folded proteins which can cause diseases such as BSE or scrapie - were found in the urine, the extraction of medicines from human urine is subject to strict regulations. Menotropin from human urine because of possible must CJK -Ansteckungsgefahr with a warning to be provided; however, there are no known sources of infection via human urine. According to the results of the Swiss prion researcher Adriano Aguzzi, the prions contained in urine are the current explanation for why prion diseases in sheep , elk and deer have relatively high rates of infection - after all, these wild animals do not feed on animal meal . However, the prions were only found in the urine when there was inflammation of the kidneys .
Communication and marking in the animal kingdom
Animals also use urine for communication ( chemocommunication ). The best known is probably the dog , which, like many other animals, delimits its territory by releasing a small amount of urine in prominent places. In some cats like leopards or cheetahs and most ungulates , the male can tell by the smell of the urine whether the female is ready to mate. When the urea contained in the environment is broken down, hydrolysis produces the pungent smelling gas ammonia .
The sexual preference for urine is also known as urophilia or undinism. The process of urinating or the urine itself is experienced as erotic and sexually stimulating . Also Urophagie , the pleasure by oral ingestion of urine (so-called "pee" ) can be connected thereto. In the corresponding scene, the names pee (often also abbreviated with "ns" ), watersports , pissing , peeing , golden shower , golden waterfalls and wet games are common. Since this sexual preference deviates significantly from the empirical norm, it is also referred to as paraphilia .
Mental and social aspects of urination
For psychological and social aspects of urination, see urination .
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