A synapse is the junction between a neurone and the next cell. At the synapse there is both a presynaptic neurone, with vesicles containing neurotransmitters (chemical messengers) and a post synaptic neuorone/cell, this has a membrane occupied by receptors specific for the neurotransmitters stored in the presynpatic neurone. When an action potential stimulates the PreS neurone, vesicles fuse with the PreS membrane - releasing neurotransmitters into the synaptic cleft ( this is the tiny gap between neurones). These neurotransmitters bind the receptors on the post synaptic membrane, here sodium channels open and an influx of sodium causes a depolarisation of the post synaptic cell. Thus, a transduction from electrical to chemical to electrical energy occurs – transmitting the message across the synapse (draw diagram).