Question

if you block ca²⁺ channels on an axon, which will not occur?
multiple choice
the depolarization phase of the action potential
the repolarization phase of the action potential
the exocytosis of neurotransmitter
the graded potential
all of these will not occur

Explanation:

Calcium - ion ($Ca^{2+}$) channels are crucial for the exocytosis of neurotransmitters. When an action potential reaches the axon terminal, the opening of $Ca^{2+}$ channels allows $Ca^{2+}$ influx, which triggers the fusion of synaptic - vesicles with the presynaptic membrane and the release of neurotransmitters by exocytosis. Depolarization and repolarization phases of the action potential are mainly mediated by sodium and potassium channels, and graded potentials are local changes in membrane potential not directly dependent on $Ca^{2+}$ channels in the same way as neurotransmitter exocytosis.

Answer:

The exocytosis of neurotransmitter