In mammals , which blood vessel would normally carry largest amount of urea ?

Options

A. Renal Vein
B. Dorsal Aorta
C. Hepatic Vein
D. Hepatic Portal Vein

Answer

**Step-by-Step Solution:**

1. **Understanding the Source of Urea**: In mammals, proteins consumed in the diet are broken down into amino acids. When the body has utilized the necessary amino acids, the excess ones are converted into waste products.

2. **Conversion of Amino Acids**: The excess amino acids undergo deamination, a process where the amino group is removed. This results in the formation of ammonia, which is highly toxic.

3. **Role of the Liver**: The ammonia produced is transported to the liver, where it undergoes the urea cycle. In this cycle, ammonia is converted into urea, which is less toxic and can be safely transported in the bloodstream.

4. **Transport of Urea**: Once formed in the liver, urea enters the bloodstream. The blood vessel that carries this urea away from the liver is the hepatic vein.

5. **Identifying the Correct Blood Vessel**: The hepatic vein is responsible for transporting blood that is rich in urea from the liver to the heart. In contrast, the renal vein, which carries blood away from the kidneys, would have a lower concentration of urea because the kidneys filter and excrete urea.

6. **Conclusion**: Therefore, the blood vessel that normally carries the largest amount of urea in mammals is the **hepatic vein**.

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