• Chemical synapses
– Action potential triggers influx of Ca2+
– Synaptic vesicles fuse with cell membrane
– Neurotransmitter is released by exocytosis
– Diffuses to other side of cleft and binds to chemical- or ligand-gated receptor proteins
– Produces graded potentials in the postsynaptic membrane
– Neurotransmitter action is terminated by enzymatic cleavage or cellular uptakes