During the transmission of nerve impulse through a nerve fibre, the potential on the inner side of the plasma membrane has which type of electric charge ?

Options

A. First positive, then negative and again back to positive
B. First negative, then positive and again back to negative
C. First positive, then negative and continue to be negative
D. First negative, then positive and continue to be positive.

Answer

To answer the question regarding the electric charge on the inner side of the plasma membrane during the transmission of a nerve impulse through a nerve fiber, we can break down the process into several steps:

### Step-by-Step Solution:

1. **Understanding the Resting Potential:**
- In a resting state, the nerve fiber's membrane is polarized. This means that the inside of the membrane has a negative charge relative to the outside. The typical resting membrane potential is around -70 mV.

2. **Ion Distribution:**
- The distribution of ions is crucial for establishing this resting potential. The inside of the neuron has a higher concentration of potassium ions (K+) and negatively charged proteins, while the outside has a higher concentration of sodium ions (Na+).

3. **Action Potential Initiation:**
- When a stimulus is applied to the neuron, it causes the membrane to become depolarized. This means that sodium channels open, allowing Na+ ions to flow into the cell, making the inside of the membrane more positive.

4. **Depolarization Phase:**
- During depolarization, the inner side of the membrane transitions from a negative charge to a positive charge. This rapid change is known as the action potential.

5. **Repolarization:**
- After the depolarization, the membrane returns to its resting state. Potassium channels open, allowing K+ ions to flow out of the cell, which restores the negative charge inside the membrane.

6. **Conclusion:**
- Therefore, during the transmission of a nerve impulse, the potential on the inner side of the plasma membrane starts as negative, becomes positive during depolarization, and then returns to negative during repolarization.

### Final Answer:
The potential on the inner side of the plasma membrane during the transmission of a nerve impulse is initially negative, becomes positive during depolarization, and then returns to negative.

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