-action potential arrives at the axon terminal
-voltage gated calcium ion channels open (due to the influx of sodium),
-calcium ions diffuse into the synaptic knob
-synaptic vesicles containing the neurotranmitter, fuse to the pre synaptic membrane (example Ach)
-exocytosis of neurotransmitter into the synpatic cleft
-neurotransmitter diffuses across synpatic cleft, which binds to receptors
-if sufficient have bound to receptors and action potential is produced, traveling along the second neurone