Ascending limb of Henle's loop is _________to water whereas the descending limb is ________to it.

Answer

To answer the question regarding the permeability of the ascending and descending limbs of the loop of Henle to water, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of the Loop of Henle**: The loop of Henle consists of two main parts: the ascending limb and the descending limb. Each limb has different properties regarding permeability to water and electrolytes.

2. **Analyze the Ascending Limb**: The ascending limb of the loop of Henle is known to be **impermeable to water**. This means that water cannot pass through this part of the nephron. Instead, it actively transports ions, particularly sodium and chloride, out of the tubular fluid into the surrounding interstitial fluid.

3. **Analyze the Descending Limb**: In contrast, the descending limb of the loop of Henle is **permeable to water**. This allows water to leave the tubular fluid and enter the surrounding interstitial fluid, which is crucial for concentrating urine.

4. **Combine the Findings**: Based on the characteristics of each limb, we can conclude that:
- The ascending limb of the loop of Henle is **impermeable** to water.
- The descending limb of the loop of Henle is **permeable** to water.

### Final Answer:
The ascending limb of Henle's loop is **impermeable** to water whereas the descending limb is **permeable** to it.

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