What is the first step in triggering a change in membrane potential?

The membrane potential is maintained in the cell due to the unequal distribution of the ions inside and outside of the cell. This membrane potential is important for the conduction of the nerve impulse.

The arrival of the stimulus triggers the action potential. The resting membrane potential is -70mV. This is maintained by the presence of potassium ions. The influx of the sodium ions result in the change in the membrane potential from -70mV to +30mV.

2%? i tried finding the exact sorry if it's not 100% correct ; -;