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Urea

Urea or carbamide (from the Greek word Ουρία) is an organic compound with the chemical formula C O( N H). The molecule has two —NH groups joined by a carbonyl (C=O) functional group.

Urea serves an important role in the metabolism of nitrogen-containing compounds by animals, and is the main nitrogen-containing substance in the urine of mammals. It is a colorless, odorless solid, highly soluble in water, and practically non-toxic ( is 15 g/kg for rats). Dissolved in water, it is neither acidic nor alkaline. The body uses it in many processes, most notably nitrogen excretion. The liver forms it by combining two ammonia molecules (NH) with a carbon dioxide (CO) molecule in the urea cycle. Urea is widely used in fertilizers as a source of nitrogen and is an important raw material for the chemical industry.

Friedrich Wöhler's discovery in 1828 that urea can be produced from inorganic starting materials was an important conceptual milestone in chemistry. It showed for the first time that a substance previously known only as a byproduct of life could be synthesized in the laboratory without biological starting materials, contradicting the widely held doctrine of vitalism.

It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.

The Collaborative International Dictionary

Urea

Urea \U"re*a\, a. [NL. See Urine.] (Physiol. Chem.) A very soluble crystalline body which is the chief constituent of the urine in mammals and some other animals. It is also present in small quantity in blood, serous fluids, lymph, the liver, etc.

Note: It is the main product of the regressive metamorphosis (katabolism) of proteid matter in the body, and is excreted daily to the amount of about 500 grains by a man of average weight. Chemically it is carbamide, CO(NH2)2, and when heated with strong acids or alkalies is decomposed into carbonic acid and ammonia. It unites with acids to form salts, as nitrate of urea, and it can be made synthetically from ammonium cyanate, with which it is isomeric.

Urea ferment, a soluble ferment formed by certain bacteria, which, however, yield the ferment from the body of their cells only after they have been killed by alcohol. It causes urea to take up water and decompose into carbonic acid and ammonia. Many different bacteria possess this property, especially Bacterium ure[ae] and Micrococcus ure[ae], which are found abundantly in urines undergoing alkaline fermentation.

Wiktionary

urea

n. 1 (context biochemistry uncountable English) A water-soluble organic compound, CO(NH2)2, formed by the metabolism of proteins and excreted in the urine. 2 (context chemistry countable English) Any ''N''-substituted derivative of urea, with the general formula (R1R2N)CO(NR3R4).

WordNet

urea

n. the chief solid component of mammalian urine; synthesized from ammonia and carbon dioxide and used as fertilizer and in animal feed and in plastics [syn: carbamide]

Douglas Harper's Etymology Dictionary

urea

compound found in the urine of animals, 1806, Latinized from French urée (1803), from Greek ouron "urine" (see urine).

Usage examples of "urea".

That the urea, which was not perfectly white, should have contained a sufficient quantity of albuminous matter, or of some salt of ammonia, to have caused the above effect, is far from surprising, for, as we shall see in the next chapter, astonishingly small doses of ammonia are highly efficient.

If someone had asked her, Crozie could not have explained that urea, which was the major component of urine, would decompose, become ammoniacal, in a warm environment.

Measurements of blood sugar, serum amylase, serum acetone, bilirubin, and blood urea nitrogen were normal.

In one breath, without removing the bowl from her lips, Tulla drinks the fatless spleen-heart-kidney-liver broth with all its granular delicacies and surprises, with the tiny bits of cartilage at the bottom, with Koshnavian marjoram and coagulated urea.

Sugars, acetone bodies, creatine, nitrogenous compounds, haemoglobin, myoglobin, amino acids and metabolites, uric acid, urea, urobilinogen and coproporphyrins, bile pigments, minerals, fats, and of course a great variety of psychotropic drugs: certainly all of the ones proscribed by the US Federal Bureau of Narcotics.

Carlisle mentions a case in which there was vomiting of a fluid containing urea and having the sensible properties of urine.

Two other summits, with their glands colourless and their utricles not shrunk, were treated with the same solution of urea.

This leaf was now immersed in a little solution of one part of urea to 146 of water, or three grains to the ounce.

This quantity usually holds in solution about one ounce of urea, and ten or twelve grains of uric acid.

The acute form of the disease is very rapid in its progress, often destroying life by uraemic poisoning--the retention of urea in the system.

Urine contains about 4 per cent solids - urea, common salt, phosphates, sulphates, potassium, sodium, calcium, magnesium, uric acid, ammonia etc.

Two other summits, with their glands colourless and their utricles not shrunk, were treated with the same solution of urea.

Drosera, 2 , coats of pollengrains not digested by insects, 117 Binz, on action of quinine on white bloodcorpuscles, 201 , on poisonous action of quinine on low organisms, 202 Bone, its digestion by Drosera, 105 Brunton, Lauder, on digestion of gelatine, 111 , on the composition of casein, 115 , on the digestion of urea, 124 , of chlorophyll, 126 , of pepsin, 124 Byblis, 343 C.

Water, ammonia, sodium chloride, potassium chloride, uric acid, creatinine, creatine, urea, phosphorus, magnesium-the list ran on.

Beyond the usual organic sediments that come from the stratospheric chemistry, there are traces of urea, organic acids, diacids, some amino acids.