Which statement is false regarding nerve impulse?

Options

A. After applying a stimulus on polarised memebrane, that site become freely permeable to `Na^(+)` and leads to rapid eflux of `Na^(+)`
B. The rise in the stimulus induced permeability to `Na^(+)` is extremeley short lived.
C. After depolarization `K^(+)` diffuses outside the membrane and restores the resting potential
D. Ionic gradients across the resting membrane are maintainined by the `Na^(+)-K^(+)` ATPase pump.

Answer

To determine which statement is false regarding nerve impulse, let's analyze each statement step by step.

### Step 1: Analyze the First Statement
**Statement:** After applying a stimulus on the polarized membrane, that site becomes freely permeable to sodium and leads to the rapid efflux of sodium.

**Analysis:** This statement is false. When a stimulus is applied to a polarized membrane, it causes depolarization, which involves the opening of sodium channels, allowing sodium ions (Na+) to flow into the cell (not efflux, which means leaving the cell). The rapid influx of sodium ions is what generates the action potential.

### Step 2: Analyze the Second Statement
**Statement:** The rise in the stimulus-induced permeability to sodium is extremely short-lived.

**Analysis:** This statement is true. The permeability of the membrane to sodium ions increases rapidly but is short-lived due to the inactivation of sodium channels shortly after they open.

### Step 3: Analyze the Third Statement
**Statement:** After depolarization, potassium diffuses outside the membrane and restores the resting potential.

**Analysis:** This statement is true. After depolarization, potassium channels open, allowing potassium ions (K+) to flow out of the cell, which helps to restore the resting membrane potential.

### Step 4: Analyze the Fourth Statement
**Statement:** The ionic gradient across the resting membrane is maintained by the sodium-potassium ATPase pump.

**Analysis:** This statement is true. The sodium-potassium pump actively transports three sodium ions out of the cell and two potassium ions into the cell, maintaining the ionic gradient essential for resting potential.

### Conclusion
Based on the analysis, the **first statement** is false regarding nerve impulse.

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