In kidneys, urine is produced by three processes

Options

A. Dialysis, ultrfiltration and tubular secretion
B. Ultrafiltration, dialysis and tubular secretion
C. Ultrafiltration, tubular reabsorption and tubular secretion
D. Tubular reabsorbtion and tubular secretion

Answer

To answer the question regarding the processes involved in urine production in the kidneys, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the three processes by which urine is produced in the kidneys.

2. **Identifying the Processes**: The three key processes involved in urine formation are:
- **Ultrafiltration**
- **Tubular Reabsorption**
- **Tubular Secretion**

3. **Explaining Ultrafiltration**:
- This is the first step in urine formation. It occurs in the glomerulus of the nephron.
- During ultrafiltration, blood is filtered through the glomerular capillaries, allowing water, glucose, amino acids, sodium chloride, and urea to pass into the Bowman’s capsule while retaining larger molecules like proteins and blood cells.

4. **Explaining Tubular Reabsorption**:
- After ultrafiltration, the filtrate moves into the renal tubules where tubular reabsorption occurs.
- In this process, useful substances such as water, glucose, and amino acids are reabsorbed back into the bloodstream from the nephric filtrate, ensuring that essential nutrients are not lost.

5. **Explaining Tubular Secretion**:
- The final step is tubular secretion, which involves the transfer of additional waste products from the blood into the nephric filtrate.
- This process helps eliminate harmful substances such as urea and certain drugs, which are secreted into the tubular fluid for excretion.

6. **Conclusion**: Therefore, the three processes involved in urine production in the kidneys are ultrafiltration, tubular reabsorption, and tubular secretion.

### Final Answer:
The correct answer is: **Ultrafiltration, Tubular Reabsorption, and Tubular Secretion**.

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