Which of the following parts of a kidney contains the lowest concentration of urea ?

Options

A. Lop of Henle
B. Branches of renal vein
C. Bowman's capsule
D. Glomerulus

Answer

To determine which part of the kidney contains the lowest concentration of urea, we can analyze the different components of the kidney and their roles in the filtration and excretion of waste.

### Step-by-Step Solution:

1. **Understand the Function of the Kidney**: The kidney's primary function is to filter blood, remove waste products (like urea), and regulate water and electrolyte balance.

2. **Identify the Parts of the Kidney**: The main parts of the nephron (the functional unit of the kidney) include the Bowman's capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

3. **Examine Urea Concentration in Different Parts**:
- **Loop of Henle**: This part is involved in the concentration of urine and typically has a higher concentration of urea.
- **Bowman's Capsule**: This is where filtration occurs, and it contains a mixture of blood components, including waste products like urea. However, it does not have the lowest concentration.
- **Collecting Duct**: This part also contains urea as it is involved in the final concentration of urine before excretion.

4. **Consider the Renal Vein**: The renal vein carries blood away from the kidney after filtration has occurred. By this point, most of the urea has been removed from the blood, resulting in a lower concentration of urea compared to other parts of the nephron.

5. **Conclusion**: Based on the analysis, the part of the kidney that contains the lowest concentration of urea is the **renal vein**. This is because it carries filtered blood that has had urea and other waste products removed.

### Final Answer:
The part of the kidney that contains the lowest concentration of urea is the **renal vein**.

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