Which of the following statements about the collecting duct in the presence of antidiuretic hormone (ADH) is correct?

• A. The collecting duct becomes permeable to water, allowing water reabsorption.
• B. The collecting duct remains impermeable to water, preventing water reabsorption.
• C. ADH has no effect on the permeability of the collecting duct.
• D. ADH causes the collecting duct to secrete water into the filtrate.

Answer: (A)

Verified step by step guidance

1. Understand the role of antidiuretic hormone (ADH): ADH is a hormone secreted by the posterior pituitary gland that regulates water balance in the body by affecting the kidneys.
2. Focus on the collecting duct: The collecting duct is a structure in the nephron of the kidney that plays a key role in water reabsorption and urine concentration.
3. Learn how ADH affects the collecting duct: ADH increases the permeability of the collecting duct to water by promoting the insertion of aquaporins (water channels) into the membrane of the duct's cells.
4. Consider the physiological outcome: When the collecting duct becomes permeable to water due to ADH, water is reabsorbed into the bloodstream, concentrating the urine and reducing water loss.
5. Eliminate incorrect options: Based on the mechanism of ADH, rule out statements that suggest the collecting duct remains impermeable to water, secretes water, or is unaffected by ADH.