In what ways does the interior surface of the membrane of a resting neuron differ from the external surface :-

Options

A. Negatively charged with less sodium
B. Negatively charged with more sodium
C. Positively charged with less sodium
D. Positively charged with more sodium

Answer

To answer the question regarding the differences between the interior surface of the membrane of a resting neuron and the external surface, we can break it down into a step-by-step explanation.

### Step-by-Step Solution:

1. **Understanding Resting Neuron**: A resting neuron is one that is not actively transmitting an impulse. It is in a state known as resting potential, which is typically around -70 millivolts.

2. **Charge Distribution**: The interior surface of the neuron's membrane is negatively charged relative to the exterior. This is due to the distribution of ions across the membrane.

3. **Ion Concentration**:
- **Potassium Ions (K+)**: The interior of the neuron has a higher concentration of potassium ions (K+) compared to the outside.
- **Sodium Ions (Na+)**: Conversely, the exterior of the neuron has a higher concentration of sodium ions (Na+) compared to the inside.

4. **Membrane Permeability**: The membrane of a resting neuron is more permeable to potassium ions than to sodium ions. This permeability allows potassium ions to flow out of the neuron more easily, contributing to the negative charge inside.

5. **Conclusion**: Therefore, the interior surface of the membrane of a resting neuron is negatively charged with less sodium compared to the external surface, which is positively charged with more sodium.

### Final Answer:
The correct answer is **A: negatively charged with less sodium**.

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