AIR1

Events during a chemical neurotransmission is as follows.
1. an action potential reaches the presynamptic neuron.
2. voltage-gated Ca++ channels open, Ca++ions enter the terminal bouton.
3. Vesicles in terminal bouton move towards the synapse
4. Vesicles fuse with presynaptic membrane
5. Transmitter substances in vesicles released into synapse, thru exocytose.
6. Transmitter substances diffuse through the synaptic cleft.
7. Transmitter substances fuse with specific receptors on the postsynaptic membrane.
8. Postsynaptic ion flux changes, depending on the types of neurotransmitters.
9. If the sum of all postsynaptic potentials is above the threshold, than a postsynaptic action potential is generated.

neurotransmitters are the relay substance for information transfer between a nerve and another cell.
it enables the nerve information to be more sophisticated, by means of time lags, excitatory or inhibitory potential production, and control of direction of information passage.

Acetylcholine is the main neurotransmitter used to relay an excitatory impulse to skeletal muscle. Its receptors are nicotinic Ach receptors.
It also works as a messenger at muscarinic Ach receptors on visceral effectors and in CNS.

Receptor agonists stimulates the receptors, to create various changes in the pre/post synaptic membrane.
Its effects may be to mimic a neurotransmitter, stimulate uptake of neurotransmitter, block a neurotransmitter channel, etc.
drugs alter neurotransmission in various ways, by controlling the release and uptake of neurotransmitters, mimicking neurotransmitters itself, etc.
clinical example; Levodopa, used to treat Parkinson’s disease. it mimics dopamine, used to alleviate the unbalance of serotonin and dopamine level. (too little dopamine)


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