Detoxification of urea takes place in the?

Analyze the question: It asks where urea is detoxified, meaning where the body deals with harmful nitrogenous waste.

Explain the concept: When proteins and amino acids are broken down, the process (deamination) releases ammonia (NH₃), which is very toxic to cells. The body converts it into urea, which is much less toxic, so it can be carried safely in the blood to the kidneys and removed in urine.

Step-by-step solution:

1. Excess amino acids are deaminated in the liver, and this produces ammonia.
2. The liver converts the ammonia into urea through the ornithine (urea) cycle.
3. Urea is released into the blood and carried to the kidneys.
4. The kidneys filter it out and it leaves the body as urine.

Checking the options:

• A. Pancreas: produces digestive enzymes and insulin/glucagon, so it is not involved in making urea.
• B. Heart: pumps blood only.
• C. Liver: site of deamination and urea formation, and it also detoxifies other harmful substances such as alcohol and drugs. ✔
• D. Testes: produce sperm and testosterone.

Answer: The liver, which is option C.

Exam tip: Remember "Liver makes urea, kidney removes urea." The liver is the body's main detoxification organ, so when you see "detoxification" in an exam question, think liver first.