In which of the following regions of nephron does maximum reabsorption of useful substances takes place?

Options

A. PCT
B. DCT
C. Henle's loop
D. Glomerulus

Answer

To determine in which region of the nephron the maximum reabsorption of useful substances occurs, we can analyze each part of the nephron:

1. **Identify the Regions of the Nephron**: The nephron consists of several parts, including:
- Proximal Convoluted Tubule (PCT)
- Distal Convoluted Tubule (DCT)
- Loop of Henle (which includes descending and ascending limbs)
- Glomerulus

2. **Understand the Function of Each Region**:
- **Proximal Convoluted Tubule (PCT)**: This is the first segment after the glomerulus. It is primarily responsible for the reabsorption of nutrients, including glucose, amino acids, ions (like sodium, potassium, and chloride), and water. It reabsorbs about 80-85% of the useful substances from the filtrate.
- **Distal Convoluted Tubule (DCT)**: This segment is involved in the reabsorption of sodium and water but to a lesser extent compared to the PCT.
- **Loop of Henle**: This part has two limbs:
- The **descending limb** is permeable to water, allowing water reabsorption.
- The **ascending limb** is impermeable to water and actively reabsorbs sodium ions.
- **Glomerulus**: This is primarily involved in ultrafiltration, where blood is filtered to form urine, but it does not reabsorb substances.

3. **Conclusion**: Given the functions of each part, the region where maximum reabsorption of useful substances occurs is the **Proximal Convoluted Tubule (PCT)**.

**Final Answer**: The maximum reabsorption of useful substances takes place in the **Proximal Convoluted Tubule (PCT)**.

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