Question

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

Answer 1

Voltage-gated calcium channels are essential for the function of the axon and axon terminal because they initiate the release of neurotransmitters following the depolarization caused by an action potential.

Step-by-step explanation:

The modality of ion channel necessary for the function of the axon and the axon terminal is the voltage-gated calcium channel. When an action potential reaches the axon terminal, it depolarizes the membrane, causing voltage-gated sodium channels (Na+) to open and sodium ions to enter the cell. This further depolarization triggers voltage-gated calcium channels (Ca2+) to open.

Calcium ions entering the cell through these channels initiate a signaling cascade that prompts synaptic vesicles to release neurotransmitters into the synaptic cleft. The neurotransmitters then bind to ligand-gated channels on the postsynaptic cell, causing them to open and modify the membrane potential of that cell, thereby continuing the signal transmission.

Answer 2

Voltage gate

Step-by-step 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.