Urea, is an organic compound: chemical formula CO(NH2)2. This amide has two –NH2 groups joined by a carbonyl (C=O) functional group.



Urea serves an important role in the metabolism of nitrogen-containing compounds.



It is the main nitrogen-containing substance in the urine.



Urea is a colorless, odorless solid, highly soluble in water, and practically non-toxic.



 It is used by the body for nitrogen excretion. 



It is formed in the liver in the urea cycle 


by combining two ammonia molecules (NH3) with a carbon dioxide (CO2)molecule.



Used in fertilizers as a source of nitrogen and is a raw material for the chemical production.



Industrially used as a a nitrogen-release fertilizer, and is used in 90% of such production.



It  has the highest nitrogen content of all solid nitrogenous fertilizers.



Urea breaks down in the soil to give ammonium. 



Used in the manufacture: used in plywood, to reduce the nitrogen oxide pollutants in exhaust gases from combustion from diesel, dual fuel, and lean-burn natural gas engines, protein denaturant , to increase the solubility of some proteins, to serve as a hydrogen source for generation in fuel cells. 



Urea-containing creams as topical dermatological products promote rehydration of the skin.



Urea 40% is indicated for: psoriasis, xerosis, onychomycosis, ichthyosis, eczema, keratosis, keratoderma, corns, and calluses, and nonsurgical debridement of nails.



It aids in the removal of ear wax.



Has been used as a diuretic, and as an abortifacient.



The blood urea nitrogen (BUN) test is a 


marker of renal function.



Thr BUN measures of the amount of nitrogen in the blood that comes from urea.



When labeled with carbon-14 or carbon-13 it can be used in the urea breath test, which is used to detect the presence of the bacterium Helicobacter pylori (H. pylori) in the stomach and duodenum of humans, associated with peptic ulcers. 



The urea breath test detects the characteristic enzyme urease, produced by H. pylori, by a reaction that produces ammonia from urea. 



This increases the pH of the stomach environment around the bacteria. 



It is used as  an ingredient in diesel exhaust fluid which is 32.5% urea and 67.5% de-ionized water to break down dangerous NOx emissions into harmless nitrogen and water.



It is used in animal feed, providing a source of nitrogen to promote growth.



It is a non-corroding alternative to rock salt for road de-icing.



It iis the main ingredient in hair removers.



A browning agent in factory-produced pretzels



An ingredient in some skin cream, moisturizers, hair conditioners, and shampoos, a cloud seeding agent, a flame-proofing agent, an ingredient in many tooth whitening products, an ingredient in dish soap, a yeast nutrient, for fermentation of sugars into ethanol, 


 a nutrient used by plankton in ocean nourishment,  as an additive to extend the working temperature and open time of hide glue, as abmoisture-retaining additive for textile dyeing or printing, and as an optical oscillator in nonlinear optics.



Urea can is an irritant to skin, eyes, and the respiratory tract. 



Skin contact with urea in fertilizer may cause dermatitis.



High concentrations of urea in the blood can be damaging. 



Ingestion of low concentrations of urea, are not dangerous.



Urea and carbon dioxide are produced by amino acids from ingested food that are used for the synthesis of proteins and other biological substances.



Urea and carbon dioxide are also produced from catabolism/ oxidation of muscle protein, as an alternative source of energy, yielding urea and carbon dioxide.



The first step in the conversion of amino acids from protein into metabolic waste in the liver is removal of the alpha-amino nitrogen, which results in ammonia. 



Ammonia is toxic, and converted into urea.



Ammonia is a byproduct of the metabolism of nitrogenous compounds. 



Ammonia is smaller, more volatile and more mobile than urea, and if allowed to accumulate, would raise the pH in cells to toxic levels. 



Urea is practically neutral and highly soluble in water, and  is a safe vehicle for the body to transport and excrete excess nitrogen.



In the urea cycle, amino groups donated by ammonia and L-aspartate are converted to urea, while L-ornithine, citrulline, L-argininosuccinate, and L-arginine act as intermediates. 



Urea production occurs in the liver, 


dissolved into the blood and transported and excreted by the kidney as a component of urine. 



There is a  small amount of urea excreted , along with sodium chloride and water in sweat.



In water, amine groups undergo slow displacement by water molecules, producing ammonia, ammonium ion, and bicarbonate ion. 



Old, stale urine has a stronger odor than fresh urine, as a result.



Urea carries waste nitrogen, and plays a role in the countercurrent exchange system of the nephrons for re-absorption of water and critical ions from the excreted urine. 



Urea is reabsorbed in the inner medullary collecting ducts of the nephrons



Urea raises the osmolarity in the medullary interstitium surrounding the thin descending limb of the loop of Henle, which makes the water reabsorb.



By action of the urea transporter 2, some of this reabsorbed urea eventually flows back into the thin descending limb of the tubule, and into the excreted urine. 



The mechanism of creating hyper osmotic urine, is controlled by the antidiuretic hormone, with a higher concentration of dissolved substances than the blood plasma, and is important to prevent the loss of water, maintain blood pressure, and maintain a suitable concentration of sodium ions in the blood plasma.



1 gram of nitrogen is roughly equivalent to 6.25 grams of protein, and 1 gram of protein is roughly equivalent to 5 grams of muscle tissue. 



In muscle wasting  1 mmol of excessive urea in the urine roughly corresponds to a muscle loss of 0.67 gram.











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