Of those listed, which event occurs first following a depolarizing stimulus applied to the presynaptic membrane of an axon terminal?
A) Voltage-gated calcium channels in the membrane open.
B) Synaptic vesicles fuse with the membrane.
C) The postsynaptic cell produces an action potential.
D) Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft.

Question

Quizplus · Accepted Answer

When a depolarizing stimulus is applied to the presynaptic membrane of an axon terminal, voltage-gated calcium channels in the membrane open, allowing calcium ions to enter the cell. This influx of calcium triggers the fusion of synaptic vesicles with the membrane and the release of neurotransmitters into the synaptic cleft. The neurotransmitters then bind to ligand-gated channels on the postsynaptic cell, leading to their opening and the production of an action potential in the postsynaptic cell. Therefore, the event that occurs first is the opening of voltage-gated calcium channels in the presynaptic membrane.

Of Those Listed, Which Event Occurs First Following a Depolarizing