Question

During depolarization, there is

• A. Closure of voltage-gated $N{a}^{+}$ and $K^{+}$ channels.
• B. Opening of voltage-gated $N{a}^{+}$ channels; voltage-gated $K^{+}$ channels are still closed.
• C. Opening of voltage-gated $K^{+}$ ion channels and closure of $N{a}^{+}$ channels.
• D. Exit of $K^{+}$ ions.

Answer 1

The correct option is B Opening of voltage-gated $N{a}^{+}$ channels; voltage-gated $K^{+}$ channels are still closed.

An action potential (depolarisation) is a transient, electrical signal, which is caused by a rapid change in resting membrane potential (-70 mV). This occurs when the threshold potential (-55 mV) is reached, this causes a rapid opening in the voltage-gated sodium channels leading to an influx of sodium ions into the cell.