Counter current exchange occurs in

Options

A. PCT
B. DCT
C. Vasa recta
D. Loop of Henle

Answer

**Step-by-Step Solution:**

1. **Understanding Counter Current Exchange:**
- Counter current exchange refers to a mechanism where two fluids flow in opposite directions, allowing for efficient exchange of substances between them. This process is crucial in the kidneys for the regulation of water and solute balance.

2. **Identifying the Location:**
- Counter current exchange occurs in the kidneys, specifically in the structures involved in urine formation and blood supply.

3. **Analyzing the Options:**
- The options provided are:
- PCT (Proximal Convoluted Tubule)
- DCT (Distal Convoluted Tubule)
- Vasarekta (Vasa Recta)
- Loop of Henle

4. **Examining Each Option:**
- **PCT and DCT:** Both of these are parts of the nephron where the same fluid (urine) flows through them. They do not exhibit counter current exchange because the fluid flows in the same direction.
- **Loop of Henle:** This structure is involved in the concentration of urine but does not directly facilitate counter current exchange with blood.
- **Vasarekta:** This is a network of blood capillaries surrounding the nephron. Blood in the vasa recta flows in the opposite direction to the urine in the nephron, facilitating counter current exchange.

5. **Conclusion:**
- Since counter current exchange involves the exchange of substances between fluids flowing in opposite directions, and the only option that fits this description is the Vasarekta, the correct answer is **Vasarekta**.

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