Question

When stimulus is applied to a membrane of neuron, it causes rapid influx of ________________.

• A. K$^+$
• B. Ca$^{++}$
• C. Mg$^{++}$
• D. Na$^+$

Hint:

Depolarization phase of action potential is always due to Na$^+$ influx.

Answer 1

The Correct Option is D

Step 1: Understanding nerve impulse initiation.
A nerve impulse begins when a neuron receives a stimulus strong enough to reach threshold potential.
Step 2: Ion movement during depolarization.
At threshold, sodium channels open rapidly, allowing Na$^+$ ions to move into the neuron.
Step 3: Effect of sodium influx.
The influx of Na$^+$ causes depolarization of the membrane, leading to the generation of an action potential.
Step 4: Conclusion.
The rapid influx of sodium ions initiates nerve impulse transmission.