<Tr> <Td> </Td> <Td> </Td> </Tr> <P> Urea, also known as carbamide, is an organic compound with the chemical formula C O (N H). This amide has two--NH groups joined by a carbonyl (C = O) functional group . </P> <P> 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 (LD 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 . </P> <P> 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 . </P>

Where does urea come from in the body