Question

Please Explain how the countercurrent exchange within the vasa recta operates to maintain the medullary osmotic gradients

Answer 1

Answer: Vasa recta walls are not permeable to Plasma Proteins but are very permeable to NaCl, urea, and water. That's why the osmotic pressure present within the vasa recta is basically much greater than the fluid present in the tissues surrounding the vasa recta. This difference in osmotic pressure causes the water movement from the interstitial fluid to asc vasa recta, which leads to its removal from the medulla.

This countercurrent exchange causing the removal of water is required for hypertonicity maintenance in interstitial fluid.