Question

Which of the following statements regarding renal handling of water by the kidneys is correct?

• A. In the absence of vasopressin, urine is isosmotic with plasma
• B. In the absence of vasopressin, water cannot be reabsorbed in the proximal tubules
• C. In the absence of vasopressin, the cortical collecting ducts have very low permeability to water
• D. In the absence of vasopressin, the distal tubules secrete water

Answer 1

The correct option is C In the absence of vasopressin, the cortical collecting ducts have very low permeability to water

In the absence of vasopressin, the entire collecting duct system has limited water permeable, and even though some water is reabsorbed due to the very large osmotic pressure gradient. Fluid that is dilute relative to plasma is delivered by the collecting ducts to the border of the outer and inner medulla.