parasympathetic NS Flashcards
(14 cards)
what is the main NT of the Para NS
Ach
how is ACh synthesized
1) choline and acetyl CoA synthesized by choline acetyltransferase
2) transported into vesicles via ACh transporter
3) degraded in synapse by acetylcholine esterase
4) reuptake via choline cotransporter with sodium
what are the pre-ganglionic receptors for Ach (same as SNS)
Nicotinic
what are the post-ganglionic receptors for PNS action on tissue/organs
muscarinic and GPCR
(ligand gated)
subtypes of muscarinic receptors
M1, M3 and M5 for stimulation
M2 and M4 for inhibition
what is the second messenger model for stimulatory muscarinic receptors
1) ACh binds to M1/M3/M5
2) causing Phospholipase C to cleabe Phosphotidyl inositol diphosphate
3) producing inositol triphosphate and diacyl glycerol
4) IP3 activates SR to release Ca2+ and DAG activaets kinses (e.g. protein kinase A) for secretion
what is the second messenger model for inhibitory muscarinic receptors
1) ACh binds to m2/M3
2) inhibition of adenyl cyclase so less CAMP for kindase activation (PKA) so less CA2+ for contraction
where are stimulatory muscarinic receptors mainly located
Salivary, GI, glands and blood vessels
where are inhibitory muscarinic receptors mainly located
cardiomyocytes and presynaptic neurons for NT release reduction
what does muscarine do
non-selective agonist of muscarinic receptors, causing poisoning from overactive para. NS
leads to salivation, urination defecation, sweating and bradycardia
direct agonists of M receptors
Muscarine
Ach
carbachol
methacholine
direct antagonists of M receptors
Atropine
hyoscine
ipratropium
indirect agonists of muscarinic receptors
acetyl cholinesterase inhibitors
‘mixed’ NS agonists (both M and Nic)
Pilocarpin
