Question

Which of the following organs synthesize urea?
A) Duodenum
B) Kidney
C) Liver
D) Pancreas

Answer 1

Hint: Urea is a nitrogen-containing compound having a simple molecular structure. The nitrogen in urea comes from amino acids, and it is a component of urine.

Complete Answer:
- The nitrogenous waste in the human body is ammonia. This ammonia is converted into urea with the help of some enzymes found in the liver.

Five enzymes are involved in the synthesis of urea, and only found in the liver are;
Carbamoyl phosphate synthase (CPS), ornithine Carbamoyltransferase (OCT), Argininosuccinate synthase, Argininosuccinate lyase, and arginase.
- Urea is a form that can easily be excreted out of the body as a component of urine. The excretion is done by the kidney.

So, the option ‘C’ that is Liver is the correct answer.

Additional information: The conversion of ammonia into urea is a two-step process, where the ammonia and carbon dioxide react to each other and form ammonium carbamate which is then dehydrated to urea. This process is called the urea cycle.
- To produce a molecule of urea two molecules of ammonia and one molecule of carbon dioxide are required.
- The ammonia comes from the metabolism of nitrogen-containing molecules such as amino acids, and carbon dioxide is a by-product of the Krebs cycle.
- The amount of urea in urine is also used for the diagnostic purpose as it reveals information about the breakdown of protein.

Note: The production and excretion are two different things. Urea is produced by the liver and excreted by the kidneys.