Describe the events of synaptic transmission

An action potential travels towards the synaptic terminal down the axon in a wave depolarisation. The voltage gated calcium channels on the membrane of the presynaptic bulb open causing an influx of calcium ions. The calcium ions facilitate the exocytosis of vesicles containing neurotransmitter into the synaptic cleft. The neurotransmitter diffuses across the synaptic cleft due to a difference in concentration. The neurotransmitter binds to specific receptors on postsynaptic membrane ion channels, the binding results in a conformational change that opens the channel and allows ions into the postsynaptic bulb. The type of neurotransmitter will depend on which type of ion enters the cell. If the threshold value of +40mV is reached in the postsynaptic terminal, an action potential will be produced to be transmitted by the post synaptic neurone.