What is acetylcholine?
Acetylcholine is a cholinergic neurotransmitter. It possesses the excitatory function
It produces the excitatory function by opening the ligand-gated sodium channels
acetylcholine acts in the following regions:
Preganglionic parasympathetic nerve
Postganglionic parasympathetic nerve
Preganglionic sympathetic nerve
Postganglionic sympathetic cholinergic nerves:
Nerves supplying eccrine sweat glands ii. Sympathetic vasodilator nerves in skeletal muscle
5. Nerves in amacrine cells of the retina
6. Basal forebrain complex
7. Ponto mesencephalic complex
Synthesis of acetylcholine
Acetylcholine is synthesized at the nerve terminal from choline and acetylcholine by enzyme choline transferase.
Acetylcholine is removed from synapse by specific acetylcholine esterase
There are two types of receptors for acetylcholine
muscarinic receptors :
Poisonous substance from toadstools called muscarine.
acts on smooth muscles and glands
Muscarinic receptors are present in all the organs innervated by the postganglionic fibres of the parasympathetic system and by the sympathetic cholinergic nerves
There are five types in muscarinic chlorogenic receptor
M1, M4 and M5 in the central nervous system
M1 on autonomic ganglion
M2 ganglion
M3 on the glands and smooth muscles
nicotinic receptors:
nicotine acts on a specific group of receptors known as nicotinic receptors
Nicotinic receptors are present in the synapses between preganglionic and postganglionic neurons of both sympathetic and parasympathetic systems.
Nicotinic receptors are also present in the neuromuscular junction on the membrane of skeletal muscle.
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