Urea vs Urine
There are differences between urea and urine though both are considered as the nitrogenous waste products that are excreted through the urinary system in animals. Metabolism of amino acids and nucleic acids results in nitrogenous wastes. When these acids are metabolized, ammonia is formed as the immediate by-product, which is quite toxic to cells and should be excreted from the body. Creatures like bony fish and many aquatic invertebrates excrete their nitrogenous waste directly as ammonia. However, in mammals, amphibians and cartilaginous fish, ammonia is quickly converted into urea by their liver and excreted as urine through the excretory system. Urea is less toxic when compared to ammonia. Birds and terrestrial reptiles excrete their nitrogenous waste in the form of uric acid. Though the production of uric acid involved more energy, it conserves a lot of water.
What is Urea?
Urea was first found and separated from human urine in 1773 by H. M. Rouelle. Urea is considered as the major organic component of humans. It is produced at the initial stage in the liver as a result of amino acid metabolism. Initially formed ammonia is first converted into urea in the liver cells and the formed urea is travelled through the blood stream to kidneys. In the kidney, urea is filtered out from the blood and excreted with urine through the urethra. Since, urea is synthesized as a result of amino acid metabolism, the amount of urea in the urine reflects the amount of protein degradation. A molecule of urea has two -NH2 groups connected via carbonyl (C=O) group, resulting the chemical formula of CO(NH₂)₂. Urea is widely used as a fertilizer, which provides nitrogen to plants. In addition, it is also used a raw material in certain chemical industries like resins, pharmaceuticals, etc.
What is Urine?
Only mammals, amphibians and cartilaginous fish excrete their nitrogenous waste in the form of Urine. Urine is produced in the kidneys by a process called urination. Urine is composed of mainly water (about 95%) and certain other water soluble organic and inorganic compounds. The main organic compounds present in the urine include urea, uric acid, creatinine, amino acid derivatives (hippurate), urochromes (formed as a result of hemoglobin degradation), hormones (catecholamines, steroids and serotonin), glucose, ketone bodies, proteins etc. The major inorganic components present in the urine are the cations (Na+, K+, Ca2+, Mg2+, and NH4+) and anions (Cl-, SO42-, and HPO42-). When the total ion concentration is considered, Na+ and Cl- represents two third of all electrolytes in urine.
An adult human usually produce 0.5 to 2.0 L of urine per day. The composition of the urine highly depends on the composition of diets and the amount of water intake. The urine composition and its appearance are used to identify certain diseases. For example, presence of high levels of glucose and ketone bodies can be used to diagnose diabetes mellitus. In addition, presence or absence of hCG (chorionic gonadotropin) in urine can be used for pregnancy tests.
What is the difference between Urea and Urine?
• Urea is first produced in the liver through the metabolism of nucleic acids and amino acids. However, urine is produced in the kidneys through the urination.
• Urea is the main organic component in urine.
• Urea is a single substance, but urine is a mixture of many substances.
• Urea can be found as a solid, but urine exists as a liquid.
• The amount of urea in the urine reflects the protein degradation in the body.