Final answer:
The total amount of neurotransmitter released at the axon terminal is related to the total number of action potentials, and is facilitated by calcium ions entering through voltage-gated Ca2+ channels.
Step-by-step explanation:
The total amount of neurotransmitter released at the axon terminal is directly related to the total number of action potentials. The release mechanism involves an action potential reaching the axon terminal and triggering voltage-gated Ca2+ channels to open. The resulting influx of calcium ions causes synaptic vesicles to merge with the presynaptic membrane, leading to neurotransmitter release via exocytosis into the synaptic cleft.
Neurotransmitter release is not related to the length of the axon, the amplitude of the action potential, or the amplitude of the graded potential. Instead, it is affected by the number of action potentials, as action potentials operate on an all-or-none principle and each action potential can trigger a release of neurotransmitter from the presynaptic neuron to the postsynaptic target.