Which one of the following blood vessels in mammals would normally carry the largest amount of urea

Options

A. Renal vein
B. Hepatic vein
C. Hepatic artery
D. Hepatic portal vein

Answer

To determine which blood vessel in mammals carries the largest amount of urea, we can analyze each of the provided options step by step.

### Step-by-Step Solution:

1. **Understand the Role of Each Blood Vessel**:
- **Renal Vein**: This vessel carries blood away from the kidneys after filtration. Since the kidneys remove urea from the blood to form urine, the renal vein will have a lower concentration of urea.
- **Hepatic Vein**: This vessel carries blood away from the liver. The liver produces urea as a waste product of protein metabolism. Therefore, the hepatic vein will carry blood that contains a significant amount of urea.
- **Hepatic Artery**: This vessel supplies oxygenated blood to the liver. It does not carry urea because it is primarily delivering oxygen and nutrients to the liver.
- **Hepatic Portal Vein**: This vessel carries blood from the gastrointestinal tract to the liver. While it may contain some urea, it primarily carries nutrients and toxins from digested food, so its urea content is relatively low.

2. **Compare Urea Content**:
- The renal vein has the least urea due to filtration in the kidneys.
- The hepatic artery has no urea as it supplies oxygenated blood.
- The hepatic portal vein may have some urea but is mainly focused on nutrients from digestion.
- The hepatic vein carries the highest concentration of urea since it is the vessel that transports blood away from the liver, where urea is produced.

3. **Conclusion**:
- Based on the analysis, the blood vessel that normally carries the largest amount of urea in mammals is the **Hepatic Vein**.

### Final Answer:
The blood vessel that normally carries the largest amount of urea is the **Hepatic Vein**.

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