Mark the false statement of the following

Options

A. The counter current mechanism involves loop of Henle and Vasa-rectae
B. The overall function of counter current mechanism is to concentrate NaCl in interstitial fluid
C. The NaCl reduces the osmotic pressure hence water diffuses out of collecting tubule into interstitial fluid
D. The absorption of water in DCT is regulated by ADH

Answer

To solve the question, we need to analyze each statement provided and determine which one is false. Let's go through the statements step by step.

### Step-by-Step Solution:

1. **Statement 1**: "Counter current mechanism involves loop of Henle and Vasa recta."
- The counter current mechanism is indeed associated with the loop of Henle and the vasa recta. The loop of Henle creates a concentration gradient in the medulla, while the vasa recta helps maintain this gradient by allowing for the exchange of substances.
- **Conclusion**: This statement is **true**.

2. **Statement 2**: "The overall function of the counter current mechanism is to concentrate sodium chloride in the interstitial fluid."
- The primary function of the counter current mechanism is to concentrate sodium chloride in the interstitial fluid, which helps in the reabsorption of water and the formation of concentrated urine.
- **Conclusion**: This statement is **true**.

3. **Statement 3**: "Sodium chloride reduces the osmotic pressure hence water diffuses out of the galactic tubule in the interstitial fluid."
- This statement is misleading. Sodium chloride actually increases osmotic pressure in the interstitial fluid, which causes water to diffuse out of the tubular fluid into the interstitial fluid. Therefore, this statement is incorrect.
- **Conclusion**: This statement is **false**.

4. **Statement 4**: "The absorption of water in distal convoluted tubule is regulated by the ADH."
- Antidiuretic hormone (ADH) indeed regulates the absorption of water in the distal convoluted tubule by increasing the permeability of the tubule to water.
- **Conclusion**: This statement is **true**.

### Final Answer:
The false statement is **Statement 3**: "Sodium chloride reduces the osmotic pressure hence water diffuses out of the galactic tubule in the interstitial fluid."