Question

Place the following events in the correct order. I. opening of voltage-gated calcium channels II. change in membrane potential of the postsynaptic neuron III. fusion of secretory vesicles with the plasma membrane of the axon terminal IV. binding of neurotransmitters to receptors on the postsynaptic neuron V. increase in cytosolic calcium levels in the presynaptic neuron VI. arrival of action potential at the axon terminal of the presynaptic neuron

Answer 1

Answer:

VI

I

V

III

IV

II

Explanation:

When the axon potential reaches the axon terminal of the presynaptic neuron the membrane is depolarised which leads to the opening of the voltage-gated calcium channels. This increases the amount of calcium in the presynaptic neuron. This increase in calcium leads to the fusion of secretory vesicles with the plasma membrane of the axon terminal which causes exocytosis of the neurotransmitter in the vesicles.

Once the neurotransmitters are in the synaptic cleft between the presynaptic and postsynaptic neurons, they bind to receptors of the postsynaptic neuron. This causes a change in membrane potential.