Question

Nerve impulse initiates with the movement of

• A. $k^{+}$
• B. $N{a}^{+}$
• C. $C{a}^{+}+$
• D. $M{g}^{+2}$

Answer 1

The correct option is B $N{a}^{+}$

Action potentials are generated by special types of voltage-gated ion channels embedded in a cell's plasma membrane. When the channels open, they allow an inward flow of sodium ions, which changes the electrochemical gradient, which in turn produces a further rise in the membrane potential. This then causes more channels to open, producing a greater electric current across the cell membrane, and so on. The rapid influx of sodium ions causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. As the sodium channels close, sodium ions can no longer enter the neuron, and then they are actively transported back out of the plasma membrane.