Video Transcript
What is the primary method for removing urea from the human body? (A) Exhaling it from the lungs. (B) Secreting it from the skin. (C) Excreting it in urine. (D) Excreting it in feces.
This question asks us how urea is removed as a waste product from the human body. Urea itself is a fairly nontoxic compound. However, it is produced from a molecule that is toxic called ammonia. Ammonia can be produced when amino acids are broken down. You might recall that amino acids contain an amino group. During amino acid metabolism, this amino group can be removed and converted into
ammonia as a waste product.
Ammonia is toxic and can be converted to the much less toxic compound urea in the
liver. Urea is then transported to the kidneys, which are the organs responsible for
filtering blood and producing urine. This urine contains waste products to be excreted. Urea can also be excreted in the sweat. However, this is not the primary way in which it is removed from the human body.
Going back to our question, the option that correctly identifies the primary method
for removing urea is given by answer choice (C), excreting it in urine.
