Explain how action potentials are transmitted across synapses.
- The action potential runs along the presynaptic membrane in a wave of depolarisation and activates the Voltage Gated Calcium ion channels. 2) Once these channels open, Ca2+ diffuses into the presynaptic neurone and activates SNARE complexes. 3) These Snare complexes transport Vesicles containing neurotransmitters to the presynaptic membrane. 4) The Vesicles then fuse with the membrane and undergo exocytosis, in which the NTs exit the vesicle and diffuse into the Synapse. 5) NTs then diffuse across the Synaptic Cleft and Bind specific receptors on the Post - Synaptic Membrane. 6) This causes Na+ channels to open on the PSM, so Na+ diffuses into the PSN causing depolarization, and so the AP is again initaited. 7) NTs are then either taken back into the PreSN via reuptake channels OR broken down by enzymes.
