In a neuron (axon) at rest the concentration of Nat is

Options

A. 10 times more in ECF than its axoplasm
B. 10 times more in axoplasm than its ECF
C. 30 tiines more in axoplasm than its ECF
D. 30 times more in ECF than its axoplasm

Answer

**Step-by-Step Solution:**

1. **Understanding Resting Potential**: In a neuron at rest, it is important to understand that the axonal membrane has a resting potential. This means that the inside of the neuron is negatively charged compared to the outside.

2. **Concentration of Sodium Ions**: At resting potential, the concentration of sodium ions (Na⁺) is higher outside the neuron than inside. This is due to the action of the sodium-potassium pump, which actively transports sodium ions out of the cell.

3. **Extracellular Fluid (ECF)**: The fluid outside the neuron is called extracellular fluid (ECF). This fluid contains a higher concentration of sodium ions compared to the fluid inside the neuron (axoplasma).

4. **Comparative Concentration**: It is established that the concentration of sodium ions in the ECF is approximately 10 times greater than that in the axoplasma. This means that for every sodium ion present inside the neuron, there are about 10 sodium ions present outside.

5. **Evaluating Statements**: Based on the information:
- The correct statement is that sodium ions are 10 times more concentrated in the ECF than in the axoplasma.
- Other statements suggesting higher concentrations in the axoplasma are incorrect.

6. **Conclusion**: Therefore, the correct answer to the question is that the concentration of sodium ions is 10 times more in the extracellular fluid (ECF) than in the axoplasma.

**Final Answer**: The concentration of sodium ions (Na⁺) in a neuron at rest is 10 times more in the extracellular fluid (ECF) than in the axoplasma.

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