Find out the correct statement about the loop of Henle

Options

A. The descending limb is permeable to electrolytes
B. The descending limb is permeable to water
C. The ascending limb is permeable to water
D. The ascending limb is impermeable to electrolytes

Answer

To find out the correct statement about the loop of Henle, we need to analyze the characteristics of its two main parts: the descending limb and the ascending limb.

### Step-by-Step Solution:

1. **Understand the Structure of the Loop of Henle**:
- The loop of Henle consists of two main parts: the descending limb and the ascending limb. Each part has different permeability characteristics.

2. **Analyze the Descending Limb**:
- The descending limb of the loop of Henle is known to be highly permeable to water. This means that water can easily move out of this limb into the surrounding medullary interstitium, which helps in concentrating the urine.
- However, the descending limb is impermeable to electrolytes (ions such as sodium and chloride).

3. **Analyze the Ascending Limb**:
- The ascending limb is characterized by its impermeability to water. This means that water cannot move out of this limb.
- Conversely, the ascending limb is permeable to electrolytes, allowing ions like sodium, potassium, and chloride to be reabsorbed back into the bloodstream.

4. **Evaluate the Given Statements**:
- **Statement 1**: "The descending limb is permeable to electrolytes." (Incorrect)
- **Statement 2**: "The descending limb is permeable to water." (Correct)
- **Statement 3**: "The ascending limb is permeable to water." (Incorrect)
- **Statement 4**: "The ascending limb is impermeable to electrolytes." (Incorrect)

5. **Conclusion**:
- The only correct statement regarding the loop of Henle is that the descending limb is permeable to water.

### Final Answer:
The correct statement about the loop of Henle is: **The descending limb is permeable to water.**