In which segment of the nephron, reabsorption is minimum?

Options

A. Proximal convoluted tubule (PCT)
B. Distal convoluted tubule (DCT)
C. Loop of henle
D. Both 1 & 2

Answer

To determine which segment of the nephron has the minimum reabsorption, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Nephron Structure**:
- The nephron is the functional unit of the kidney and consists of several segments: the proximal convoluted tubule (PCT), loop of Henle (LOH), and distal convoluted tubule (DCT).

2. **Identify the Function of Each Segment**:
- **Proximal Convoluted Tubule (PCT)**: This segment is responsible for the majority of reabsorption, approximately 90% of filtered substances such as glucose, sodium, and chloride ions.
- **Loop of Henle (LOH)**: This segment has two parts - the descending limb and the ascending limb. The descending limb is permeable to water, while the ascending limb is permeable to sodium and chloride ions. However, overall reabsorption here is less compared to PCT.
- **Distal Convoluted Tubule (DCT)**: This segment reabsorbs some electrolytes, calcium ions, and phosphate ions, but the amount is less than that in the PCT.

3. **Compare the Amount of Reabsorption**:
- Maximum reabsorption occurs in the PCT.
- The loop of Henle has the least amount of reabsorption compared to the PCT and DCT.
- The DCT has an average level of reabsorption, which is more than the loop of Henle but less than the PCT.

4. **Conclusion**:
- Based on the comparison, the segment of the nephron where reabsorption is minimum is the **Loop of Henle**.

### Final Answer:
The segment of the nephron where reabsorption is minimum is the **Loop of Henle**.

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