Action potential of a nerve cell is

Options

A. `- 60` mv
B. `- 80` mv
C. `+ 20` mv
D. `+60` mv

Explanation

**Step-by-Step Solution:**

1. **Understanding Resting Potential:**
- The resting membrane potential of a nerve cell is typically around -70 mV. This means that the inside of the neuron is negatively charged compared to the outside.

2. **Stimulus Application:**
- When a stimulus is applied to a specific point on the neuron (let's call it point A), it causes changes in the permeability of the membrane, specifically allowing sodium ions (Na+) to flow into the neuron.

3. **Depolarization:**
- As sodium ions enter the neuron, they carry a positive charge with them. This influx of positive charge causes the inside of the neuron to become less negative (or more positive), leading to a state known as depolarization.

4. **Action Potential Formation:**
- The change in electrical potential across the membrane due to the influx of sodium ions is referred to as the action potential. At the peak of this action potential, the membrane potential can reach approximately +20 mV.

5. **Conclusion:**
- Therefore, the action potential of a nerve cell is +20 mV, which is the result of the rapid influx of sodium ions during depolarization.

**Final Answer:**
The action potential of a nerve cell is +20 mV.

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