The most significant pathway for ammonia removal in brain is

Options

A. Urea formation
B. Glutamine formation
C. Carbamoyal phosphate formation
D. Aspartate formation

Answer

To answer the question about the most significant pathway for ammonia removal in the brain, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ammonia in the Brain**:
- Ammonia is a toxic byproduct that can accumulate in the brain and lead to adverse effects, including brain damage.

2. **Role of Glutamine**:
- The brain utilizes glutamine as a primary pathway for the detoxification of ammonia. Glutamine is formed when ammonia reacts with glutamate, a neurotransmitter.

3. **Enzyme Involvement**:
- The enzyme responsible for the conversion of glutamate and ammonia into glutamine is called glutamine synthase. This enzyme plays a crucial role in regulating the excitatory and inhibitory activities of neurotransmitters in the brain.

4. **Location of Process**:
- The synthesis of glutamine from ammonia occurs mainly in astrocytes, which are star-shaped glial cells in the brain that support neuronal function.

5. **Comparison with Other Pathways**:
- Other pathways like urea formation, carbamoyl phosphate formation, and aspartate formation are less significant for ammonia removal in the brain. Urea formation occurs primarily in the liver and is not a direct pathway for ammonia removal in the brain.

6. **Conclusion**:
- Therefore, the most significant pathway for ammonia removal in the brain is through the formation of glutamine via the action of glutamine synthase in astrocytes.

### Final Answer:
The most significant pathway for ammonia removal in the brain is the formation of glutamine.

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