Aldosterone stimulates sodium reabsorption and potassium secretion mainly in

Options

A. descending limb of the loop of Henle
B. ascending limb of the loop of Henle
C. proximal convoluted tubule
D. distal convoluted tubule

Answer

**Step-by-Step Solution:**

1. **Understanding Aldosterone**: Aldosterone is a hormone secreted by the zona glomerulosa of the adrenal cortex. It plays a crucial role in regulating sodium and potassium levels in the body.

2. **Function of Aldosterone**: The primary function of aldosterone is to stimulate sodium reabsorption in the kidneys while promoting the secretion of potassium. This process helps maintain electrolyte balance and blood pressure.

3. **Identifying the Site of Action**: Aldosterone mainly acts on specific parts of the nephron, which is the functional unit of the kidney. The nephron consists of several segments, including the proximal convoluted tubule (PCT), loop of Henle (which has descending and ascending limbs), and distal convoluted tubule (DCT).

4. **Analyzing Each Option**:
- **Descending Limb of Loop of Henle**: This segment is primarily involved in water reabsorption, not sodium or potassium regulation.
- **Ascending Limb of Loop of Henle**: This part is involved in sodium reabsorption but does not significantly involve aldosterone's action regarding potassium secretion.
- **Proximal Convoluted Tubule (PCT)**: While this segment reabsorbs a significant amount of sodium and other nutrients, it does not rely on aldosterone for its function.
- **Distal Convoluted Tubule (DCT)**: This is the primary site where aldosterone exerts its effects, stimulating sodium reabsorption and potassium secretion.

5. **Conclusion**: Based on the functions of aldosterone and the roles of different nephron segments, the correct answer is that aldosterone stimulates sodium reabsorption and potassium secretion mainly in the **distal convoluted tubule (DCT)**.

**Final Answer**: The correct option is the **fourth option: distal convoluted tubule**.

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