At approximately –50 mV, is reached, Gate 1 of the voltage-activated Na+ channels opens, and Na+ ions the neuron due to voltage and concentration gradients.

threshold, enter

Explanation:

Sodium channels may be defined as the integral membrane proteins which  forms the ion channels. It conducts the sodium ions through the cell's plasma membrane.

These channels are said to be located in the chromosome 2 of the human a well as mouse species. Sodium channels functions to mediate the fast depolarization and it conduct the electrical impulses throughout the nerves,  heart and the muscles.

The sodium channel opens when a threshold is reached at -50mV to -55 mV which causes the rapid opening of the voltage-gated sodium channels.

ya the other dude is right

d. organisms have cells with different shapes and functions.