Which blood vessel has the largest amount of urea ?

Options

A. Dorsal aorta
B. Hepatic vein
C. Hepatic artery
D. Dorsal portal vein

Answer

To determine which blood vessel has the largest amount of urea, we can analyze the functions of the different blood vessels mentioned in the question: dorsal aorta, hepatic vein, hepatic artery, and dorsal portal vein.

### Step-by-Step Solution:

1. **Understanding Urea Production**:
- Urea is a nitrogenous waste product formed primarily in the liver from the breakdown of amino acids. This process is known as deamination, where amino acids are converted into ammonia and then into urea.

2. **Identifying the Role of the Liver**:
- The liver is crucial for protein metabolism and urea formation. After urea is produced in the liver, it enters the bloodstream.

3. **Examining the Blood Vessels**:
- **Hepatic Vein**: This vessel carries blood away from the liver. Since the liver produces urea, the blood in the hepatic vein will have a high concentration of urea.
- **Hepatic Artery**: This vessel supplies oxygenated blood to the liver. It does not carry urea as it is bringing nutrients and oxygen to the liver for metabolism.
- **Dorsal Aorta**: This is a major artery that carries oxygenated blood to the body. It does not have a significant concentration of urea.
- **Dorsal Portal Vein**: This vessel carries blood from the digestive tract to the liver. While it may contain some urea, it is not as concentrated as the blood in the hepatic vein.

4. **Conclusion**:
- Since the hepatic vein is responsible for carrying blood away from the liver, where urea is produced, it will have the largest amount of urea compared to the other blood vessels listed.

### Final Answer:
The blood vessel with the largest amount of urea is the **hepatic vein**.