The counter-current mechanism in the nephron helps in concentrating urine and conserving water. It occurs between Henle’s loop and the vasa recta (capillary network).

How It Works

• The descending limb of Henle’s loop is permeable to water but not salts.
• The ascending limb is impermeable to water but pumps out salts.
• This creates a concentration gradient in the medulla.
• The vasa recta maintains this gradient by acting as a counter-current exchanger.

Result: Water is reabsorbed from the collecting duct - urine becomes concentrated.