Loop of Henle plays a significant role in the maintenance of

Options

A. low osmolarity in medullary interstitial fluid
B. high osmolarity in cortical interstitial fluid
C. low osmolarity in cortical interstitial fluid
D. high osmolarity in medullary interstitial fluid

Answer

**Step-by-Step Solution:**

1. **Understanding the Loop of Henle**: The Loop of Henle is a U-shaped structure in the nephron of the kidney that plays a crucial role in the concentration of urine and the maintenance of osmolarity in the interstitial fluid of the kidney.

2. **Identifying the Regions**: The kidney is divided into two main regions: the cortex and the medulla. The Loop of Henle extends from the cortex into the medulla. The medulla can be further divided into outer and inner medulla.

3. **Osmolarity in Different Regions**:
- The osmolarity refers to the concentration of solutes in a solution.
- In the cortex, the osmolarity is relatively low (around 300 mOsm/L), indicating fewer solutes.
- In contrast, the medullary region has a higher osmolarity, ranging from 400 to 1200 mOsm/L, due to a higher concentration of solutes like NaCl.

4. **Role of the Loop of Henle**: The Loop of Henle helps create a concentration gradient in the medulla. The descending limb is permeable to water but not to salts, allowing water to leave and concentrate the filtrate. The ascending limb is impermeable to water but actively transports salts out, which helps to maintain high osmolarity in the medullary interstitial fluid.

5. **Conclusion**: Given the role of the Loop of Henle in maintaining osmolarity, it significantly contributes to the high osmolarity of the medullary interstitial fluid. Therefore, the correct answer is that the Loop of Henle plays a significant role in maintaining **high osmolarity in the medullary interstitial fluid**.

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