Question

Components responsible for counter current mechanism in kidney are all except:

• A. Sodium outflow in thick ascending limb
• B. Water outflow in thin descending limb
• C. Sodium outflow in thin ascending limb
• D. Flow of tubular fluid from PCT to DCT

Answer 1

The Correct Option is C

The counter-current mechanism in the kidney is a crucial physiological process primarily involving the Loop of Henle in nephron function. The key components of this mechanism include:

• Sodium outflow in thick ascending limb: In this part, sodium ions are actively transported out of the thick ascending limb of the Loop of Henle, contributing to the generation of a hyperosmotic medulla, which is crucial for water reabsorption.
• Water outflow in thin descending limb: This section of the loop allows water to leave the tubule due to the osmotic gradient, allowing urine to concentrate appropriately.
• Flow of tubular fluid from PCT to DCT: The movement of filtrate from the proximal convoluted tubule (PCT) through the Loop of Henle to the distal convoluted tubule (DCT) is integral to the counter-current multiplier effect.

However, sodium outflow in the thin ascending limb is not a component of the counter-current mechanism directly involved, as this portion is impermeable to water and primarily allows passive sodium reabsorption, which contributes less to the counter-current multiplier system compared to other components.

Thus, the correct answer is: Sodium outflow in thin ascending limb.