TRANSMISSION OF ACTION POTENTIALS BETWEEN NERVE CELLS
How action potentials are transmitted:
o Action potential arrives at presynaptic knob, causing
Ca2+ voltage gated channels to open
o Ca2+ ions cause exocytosis of
Acetylcholine (ACh)
vesicles (synapses that have acetylcholine
are called
cholinergic synapses)
o ACh moves to presynaptic knob temporarily binding to
the receptor
proteins that have complimentary shape
o This causes Na+ (chemical) channels in post synoptic
knob to open, Na+ enter and cause depolarisation
o Ach is then recycled by enzyme acetylcholinesterase
which
breaks the it into acetate and choline which then
recombined
in the presynaptic knob
Note: If ACh is
not broken down the Na+ channels will remain open so neurone will be permanently depolarised
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