During urine formation, which of the following process helps in maintaining osmotic pressure in the uriniferous tubule?

Options

A. Active `Na^(+)` absorption , followed by absorption of `Cl^(-)`
B. Active `Cl^(+)` absorption , followed by absorption of `Na^(+)`
C. Active secretion of `Na^(+)` into efferent arteriole followed by absorption of `Cl^(-)` into efferent renal arteriole
D. Active secretion of `Cl^(-)` and absorption of `N^(+)a` into efferent renal arteriole

Answer

To solve the question regarding which process helps in maintaining osmotic pressure in the uriniferous tubule during urine formation, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Urine Formation**:
- Urine formation occurs in the nephron, which consists of various parts including the glomerulus, proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), and collecting duct. Each part plays a role in filtering blood and forming urine.

2. **Role of Osmotic Pressure**:
- Osmotic pressure is crucial for the reabsorption of water and solutes in the nephron. It helps maintain the balance of fluids in the body and ensures that essential substances are not lost in urine.

3. **Sodium Reabsorption**:
- Sodium ions (Na+) are actively reabsorbed in the nephron, primarily in the proximal convoluted tubule (PCT). This process is essential because sodium is a key electrolyte that influences osmotic pressure.

4. **Chloride Reabsorption**:
- Following the reabsorption of sodium, chloride ions (Cl-) are also reabsorbed. The movement of sodium creates an osmotic gradient that allows water to follow, thus maintaining osmotic pressure.

5. **Analyzing the Options**:
- The options provided in the question include various sequences of sodium and chloride absorption:
- Active sodium absorption followed by absorption of chlorine
- Active chlorine absorption followed by absorption of sodium
- Active secretion of sodium into efferent arteriole followed by absorption of chlorine into efferent renal arteriole
- Active secretion of chlorine and absorption of nitrogen into efferent renal arteriole

6. **Correct Answer**:
- The correct process that helps in maintaining osmotic pressure is **active sodium absorption followed by absorption of chlorine**. This sequence ensures that the osmotic balance is maintained, allowing for efficient water reabsorption and proper urine formation.

### Final Answer:
**Active sodium absorption followed by absorption of chlorine.**

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