What mechanisms are responsible for producing concentrated urine?
A) the juxtamedullary nephrons become active.
B) the counter-current mechanism pulls out much water.
C) vasopressin causes facultative water reabsorption in distal tubule.
D) both (a) and (b) above.
E) all of these answers.

Question

Quizplus · Accepted Answer

All of the mechanisms listed contribute to the production of concentrated urine. The juxtamedullary nephrons are responsible for establishing the concentration gradient in the renal medulla, while the countercurrent mechanism helps to maintain this gradient and pull out water from the collecting ducts. Vasopressin (also known as antidiuretic hormone) is released in response to dehydration and causes the distal tubules and collecting ducts to reabsorb more water, leading to further urine concentration. Therefore, all three mechanisms (a, b, and c) work together to produce concentrated urine.

What Mechanisms Are Responsible for Producing Concentrated Urine