Tubular reabsorption occurs in
I Proximal convoluted tubule.
II collecting ducts
III Loop of henle
IV Bowman's capsule
Choose the correct answer

Options

A. I and IV
B. II and iII
C. I and II
D. All of these

Answer

To solve the question regarding where tubular reabsorption occurs, we will analyze each option provided:

1. **Proximal Convoluted Tubule (PCT)**:
- The proximal convoluted tubule is the first segment of the renal tubule. It is primarily responsible for the reabsorption of water, ions, and all organic nutrients. Approximately 65-70% of the filtrate is reabsorbed here.
- **Conclusion**: Tubular reabsorption occurs in the PCT.

2. **Collecting Duct**:
- The collecting duct is involved in the reabsorption of water and sodium ions, influenced by hormones such as aldosterone and antidiuretic hormone (ADH). This is crucial for the regulation of water balance and blood pressure.
- **Conclusion**: Tubular reabsorption also occurs in the collecting duct.

3. **Loop of Henle**:
- The Loop of Henle plays a role in the concentration of urine but is primarily involved in the counter-current multiplication mechanism. While some reabsorption occurs here, it is not classified as a major site for tubular reabsorption compared to the PCT and collecting duct.
- **Conclusion**: Tubular reabsorption is not significant in the Loop of Henle.

4. **Bowman's Capsule**:
- Bowman's capsule is the initial part of the nephron where filtration occurs, but it does not participate in reabsorption. Its main function is to collect the filtrate from the blood.
- **Conclusion**: Tubular reabsorption does not occur in Bowman's capsule.

**Final Answer**: The correct options where tubular reabsorption occurs are I (Proximal Convoluted Tubule) and II (Collecting Duct).

### Summary of Correct Answer:
- **I and II**: Proximal Convoluted Tubule and Collecting Duct.