Acetylcholine

 ACETYLCHOLINE

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:

1.  Preganglionic parasympathetic nerve 

2.  Postganglionic parasympathetic nerve 

3.  Preganglionic sympathetic nerve 

4.  Postganglionic sympathetic cholinergic nerves:

1. 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. Pontomesencephalic complex

Synthesis of acetylcholine

Acetylcholine is synthesised 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.