What is the series of events that occur when an action potential enters the presynaptic neuron

The membrane around the presynaptic neurone depolarises This depolarisation causes Ca2+ voltage-gated channels to open and Ca2+ influxesCa2+ causes vesicles with specific neurotransmitters to migrate to the membrane, fuse, and release the neurotransmitter into the synaptic cleft The neurotransmitters bind to specific neurotransmitter receptors on the post-synaptic membrane, this causes ion channels, specific to that receptor to open and cause depolarisation in the post-synaptic neurone A graded potential is produce, if it reaches the threshold potential, the action potential is fired up