During the propagation of a nerve impulse, the action potential results from the movement of

Options

A. `Na^(+)` ions from extracellular fluid to intracellular fluid
B. `K^(+)` ions from extracellular fluid to intracellular fluid
C. `Na^(+)` ions from intracellular fluid to extracellular fluid
D. `K^(+)` ions from intracellular fluid to extracellular fluid

Answer

**Step-by-Step Solution:**

1. **Understanding Nerve Impulse and Action Potential**:
- A nerve impulse, also known as an action potential, is a rapid change in the electrical potential across the membrane of a neuron. This change is crucial for the transmission of signals in the nervous system.

2. **Role of Ions in Action Potential**:
- The action potential is primarily generated by the movement of sodium (Na⁺) and potassium (K⁺) ions across the neuron's membrane.

3. **Movement of Sodium Ions**:
- During the initial phase of the action potential, sodium channels in the neuron's membrane open, allowing Na⁺ ions to flow from the extracellular fluid (outside the cell) into the intracellular fluid (inside the cell). This influx of positive sodium ions causes the inside of the neuron to become more positive, leading to depolarization.

4. **Movement of Potassium Ions**:
- Following the influx of sodium ions, potassium channels open, allowing K⁺ ions to move from the intracellular fluid to the extracellular fluid. This movement helps to repolarize the neuron, returning it to its resting membrane potential.

5. **Conclusion**:
- Therefore, the correct answer to the question is that during the propagation of a nerve impulse, the action potential results from the movement of Na⁺ ions from the extracellular fluid to the intracellular fluid.

**Final Answer**: Na⁺ ions from extracellular fluid to intracellular fluid.

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