Which one of the following ions is required for nerveimpulse transmission at the neuromuscular junction?

Options

A. Magnesium
B. Chloride
C. Calcium
D. Iron

Answer

To solve the question about which ion is required for nerve impulse transmission at the neuromuscular junction, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Neuromuscular Junction**:
- The neuromuscular junction is the site where a motor neuron communicates with a muscle fiber to initiate muscle contraction.

2. **Role of Nerve Impulses**:
- Nerve impulses are electrical signals that travel along neurons and are essential for communication between neurons and muscle cells.

3. **Transmission Mechanism**:
- When a nerve impulse reaches the neuromuscular junction, it triggers the release of neurotransmitters (like acetylcholine) from the neuron into the synaptic cleft.

4. **Importance of Calcium Ions**:
- The arrival of the nerve impulse causes depolarization of the presynaptic membrane, which opens voltage-gated calcium channels.
- Calcium ions (Ca²⁺) flow into the neuron, which is crucial for the release of acetylcholine.

5. **Conclusion**:
- The presence of calcium ions is essential for the transmission of nerve impulses at the neuromuscular junction. Therefore, the correct answer to the question is **calcium ions (Ca²⁺)**.

### Final Answer:
C. Calcium ions

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