Final answer:
The initial electrical signals moving along the axon (pre-synaptic cell) use voltage-gated Na+ channels to allow Na+ ions to enter the cell and depolarize the membrane. This depolarization triggers the opening of voltage-gated Ca²+ channels, leading to the release of neurotransmitter molecules.
Step-by-step explanation:
The initial electrical signals moving along the axon (pre-synaptic cell) use voltage-gated Na+ channels. These channels are responsible for allowing Na+ ions to enter the cell and further depolarize the presynaptic membrane. The depolarization then triggers the opening of voltage-gated Ca²+ channels, which allows calcium ions to enter the cell and initiate a signaling cascade that leads to the release of neurotransmitter molecules.