Select the incorrect statement regarding mechanism of urine formation in man.

Options

A. Tubular secretion takes place in the PCT also
B. Aldosterone induces greater reabsorption of sodium
C. The counter current systems contrivute in diluting the urine
D. The glomerular filtration rate is about 125 mL per minute

Answer

To solve the question regarding the incorrect statement about the mechanism of urine formation in humans, we will analyze each statement provided and determine its validity step by step.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "The tubular secretion takes place in PCT also."
- **Explanation**: The Proximal Convoluted Tubule (PCT) is indeed involved in tubular secretion. Various substances such as ions and waste products are secreted into the tubule from the blood.
- **Conclusion**: This statement is **true**.

2. **Statement 2**: "Aldosterone induces greater reabsorption of sodium."
- **Explanation**: Aldosterone is a hormone that plays a crucial role in regulating sodium and potassium levels in the body. It promotes the reabsorption of sodium in the kidneys, specifically in the distal convoluted tubule and collecting ducts.
- **Conclusion**: This statement is **true**.

3. **Statement 3**: "The counter current system contributes in diluting the urine."
- **Explanation**: The counter current mechanism primarily functions to concentrate urine, not dilute it. It involves the flow of fluids in opposite directions in adjacent tubules, which helps in the reabsorption of water and solutes, leading to concentrated urine.
- **Conclusion**: This statement is **false**.

4. **Statement 4**: "The glomerular filtration rate is about 125 ml per minute."
- **Explanation**: The normal glomerular filtration rate (GFR) for a healthy adult is approximately 125 ml/min. This is a standard measure of kidney function.
- **Conclusion**: This statement is **true**.

5. **Final Conclusion**:
- The incorrect statement regarding the mechanism of urine formation in man is: **"The counter current system contributes in diluting the urine."**

### Answer:
The incorrect statement is: **"The counter current system contributes in diluting the urine."**

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