Urea is a nitrogen-containing compound that is produced as a waste product in the metabolism of amino acids. It is typically excreted in the urine, although it can also be found in sweat and other body fluids. Urea is highly soluble in water and has a high osmotic pressure, which makes it an effective diuretic. It is also a major component of many commercial fertilizers.
Urea was first isolated from urine by the chemist Friedrich Wöhler in 1828. He later synthesized it from ammonium cyanate, making it the first organic compound to be synthesized from inorganic starting materials. The urea molecule consists of two nitrogen atoms bonded together by a single oxygen atom. The compound has the formula NH2CONH2.
The process of urea production begins with the breakdown of amino acids in cells. Amino acids are broken down into ammonia (NH3) and carbon dioxide (CO2). The ammonia is then converted into urea by enzymes known as ureases. Ureases are found in most tissues, but they are particularly concentrated in the liver and kidney tissues where urea is produced.
After its formation, urea diffuses across cell membranes into the bloodstream where it circulates to all parts of the body. Most of the urea that is excreted by the body is filtered out of the blood by the kidneys and passed out in urine. Smaller amounts are eliminated through sweating and other body fluids such as tears and saliva.
Urea has a number of important functions in addition to its role as a waste product removal system. It helps to regulate fluid balance within cells and maintains blood pressure by acting as an osmotic agent . In addition, urea provides essential nutrients for plants, being one of the main components of commercial fertilizer products . Plants absorb nitrogen from soil solutions primarily in the form of nitrate ions (NO3-). However, some plants can also use ammonium ions (NH4+) or even atmospheric nitrogen gas (N2) as their sole source of nitrogen . When applied to soils , these different nitrogen sources convert over time into nitrate via several complex biochemical pathways involving bacteria , fungi , protozoa , and algae . All these organisms need energy to power this transformation process, which they obtain either through respiration using organic matter or photosynthesis using sunlight . This decomposition/nitrification process eventually decreases soil fertility unless more organic matter or fertilizer is added back to replenish lost nutrients