Acetylcholine Flashcards
When is ACh released from the post ganglion in the sympathetic nervous system?
In sweat glands.
What is the receptor for ACh at the preganglionic synapse, and post ganglionic synapse respectively?
Pre- nicotinic
Post- muscarinic
Where does ACh act when released parasympathetically and what effects does it have? (4)
- heart- M2 receptors- negative chronotropy
- bronchi- M3 receptors- bronchoconstriction
- bladder- M3 receptors- bladder contraction
- glands- M3 receptors- increased secretion
How is acetylcholine synthesised?
From acetyl coA and choline using choline acetyl transferase enzyme, in the pre synaptic knob.
What packages ACh into vesicles ready for release?
Vesicular ACh transporter
How is ACh released from the pre synaptic knob when an AP arrives?
Arrival of an AP causes voltage gated calcium channels to open and calcium ions to influx into the knob.
Calcium binds to synaptotagmin to form a snare complex.
The vesicle if brought to the membrane edge and ACh is released through the pore in the snare complex.
How is ACh action terminated? What is it converted to? What happens to the components?
Using acetylcholine esterase into acetate and choline.
The acetate diffuses into the surrounding medium, where as the choline is recaptured into the pre-synaptic knob by high affinity choline uptake system and is used for further ACh production.
What is the affect of parasympathetic innervation on the eye?
-ciliary muscles and sphincter muscles both contract.
Allows focus on nearby objects.
Decreased intra ocular pressure as trabecular meshwork is opened.
What is glaucoma?
An abnormally raised intra ocular pressure which can cause damage to the optic nerve, and eventually blindness.
What are the causes of glaucoma? (5)
Steroids Diabetes Ethnicity Sex Age
Which branch of the ANS is ACh always released from?
Parasympathetic branch
