Excitatory neurotransmitter involved in transmission of impulse at neuromuscular junction is

Options

A. Epinephrine
B. Serotonin
C. Acetylcholine
D. Glycine.

Answer

### Step-by-Step Solution:

1. **Understanding the Neuromuscular Junction**: The neuromuscular junction is the site where a motor neuron communicates with a muscle fiber. This junction is crucial for the transmission of nerve impulses that lead to muscle contraction.

2. **Role of Neurotransmitters**: At the neuromuscular junction, neurotransmitters are released from the nerve endings to transmit signals to the muscle. These neurotransmitters bind to specific receptors on the muscle fibers, initiating a response.

3. **Identifying the Excitatory Neurotransmitter**: The primary excitatory neurotransmitter involved in this process is acetylcholine (ACh). When an action potential reaches the axon terminal of the motor neuron, acetylcholine is released into the synaptic cleft.

4. **Mechanism of Action**: Once released, acetylcholine binds to acetylcholine receptors on the muscle cell membrane. This binding causes ion channels to open, leading to depolarization of the muscle cell membrane and ultimately resulting in muscle contraction.

5. **Evaluating Other Options**:
- **Epinephrine**: While it is an excitatory neurotransmitter, it is not primarily involved in the neuromuscular junction.
- **Serotonin**: This neurotransmitter is mainly inhibitory and does not facilitate muscle contraction.
- **Glycine**: This is also an inhibitory neurotransmitter and does not play a role in muscle contraction.

6. **Conclusion**: Based on the information, the correct answer to the question is acetylcholine, as it is the primary excitatory neurotransmitter involved in the transmission of impulses at the neuromuscular junction.

### Final Answer:
The excitatory neurotransmitter involved in the transmission of impulse at the neuromuscular junction is **acetylcholine**.

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