What modality of ion channel is necessary for the function of the axon and the axon terminal?

Voltage gate

Explanation:

An action potential is a localized change in electrical potential between the ion inside and outside of the nerve fibre when stimulated. The inside becomes positively charged while the outside becomes negatively charged. This is called depolarisation.

The membrane becomes more permeable and because the sodium pump temporarily ceases, causing an influx by diffusion of Na+ into the axoplasm. This raises the concentration of Na+ ions within the axoplasm relative to the outside causing the K+ ions to diffuse out. The movement of this action potential along a nerve  fibre constitutes a nerve impulse.