Counter current mechanism observed in the renal medulla helps in formation of
concentrated urine
dilute urine
reabsorption of nutrients
reabsorption of creatinine

Options

A. concentrated urine
B. dilute urine
C. reabsorption of nutrients
D. reabsorption of creatinine

Answer

**Step-by-Step Solution:**

1. **Understanding the Countercurrent Mechanism**: The countercurrent mechanism is a physiological process that occurs in the kidneys, specifically in the renal medulla. It involves the interaction between the loop of Henle and the vasa recta.

2. **Role of the Loop of Henle**: The loop of Henle consists of a descending limb and an ascending limb. In this mechanism, the filtrate flows down the descending limb and up the ascending limb. The descending limb is permeable to water but not to salts, while the ascending limb is permeable to salts but not to water.

3. **Role of the Vasa Recta**: The vasa recta are capillaries that run parallel to the loop of Henle. Blood in the vasa recta flows in the opposite direction to the filtrate in the loop of Henle, which is crucial for the countercurrent exchange.

4. **Sodium Chloride (NaCl) Movement**: As the filtrate moves through the ascending limb of the loop of Henle, sodium chloride is actively transported out into the interstitial fluid. This creates a high osmolarity in the medulla, which is essential for water reabsorption.

5. **Urea Recycling**: A small amount of urea also moves from the collecting duct into the thin segment of the ascending limb of the loop of Henle. This urea contributes to the osmolarity of the medullary interstitium, further aiding in the concentration of urine.

6. **Formation of Concentrated Urine**: Due to the high osmolarity created by the countercurrent mechanism, water is reabsorbed from the collecting ducts back into the bloodstream, leading to the formation of concentrated urine.

7. **Conclusion**: Therefore, the countercurrent mechanism observed in the renal medulla primarily helps in the formation of concentrated urine.

**Final Answer**: Concentrated urine.

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