Urea

Multiple Choice

Urea

A) is a waste product resulting from the breakdown of protein.
B) is passively reabsorbed at the end of the proximal tubule down a urea concentration gradient created by the osmotic-induced reabsorption of water from the proximal tubule.
C) recycling between the late portion of the collecting tubule and the long loops of Henle contributes to medullary hypertonicity.
D) both (a) and (b) above.
E) all of these answers.