Diffusion across synaspes

Action potential arrives at the pre synaptic knob stimulates calcium channels to open diffusing calcium in causing vesicles containing neurotransmitters to fuse with pre synaptic membrane realasing ach ach diffuses across synaptic cleft ach binds with receptor proteins trigerring sodium gated channels to open so sodium diffuses in by FD , if enough sodium diffuses in , threshold is passed. impulses continue