Pharma - Neuromuscular junction Flashcards
features of the ANS
involuntary - glands, cardiac tissue, metabolic activity
regulated by brain stem centres
features of the SNS
voluntary body movements
regulated by corticospinal tracts and spinal reflexes
where are the neuromuscular junctions of the para and sympathetic NS located
parasympathetic - postganglionic neurone
sympathetic - preganglionic neurone
outline acetylcholine synthesis
pyruvate dehydrogenase converts pyruvate into acetyl-CoA and choline
cholineacetyltransferase converts that into acetylcholine
what converts ACh into acetate + choline
acetylcholinesterase
features of acetylcholine
requires 2 ACh to activate
5 different sub-types:
alpha, beta, gamma, delta, epsilon
how many types of Nm receptors are there
alpha1
beta1
delta
gamma
epsilon
how types of Nn receptors are there
alpha2-10
beta2-4
what causes grave muscle weakness (myasthenia gravis)
autoantibodies bind to nicotinic AChR on the motor end plates of muscle
how does autoantibodies binding to MuSK contribute to myasthenia gravis
prevents ACh from clustering at the neuromuscular junction
what causes Lambert-Eaton myasthenic syndrome
autoantibodies binding to voltage gated calcium channel
outline Lambert-Eaton myasthenic syndrome
interferes with calcium-dependent ACh release
reduced endplate potential at the post-synaptic membrane
results in NMJ transmission failure
what occurs when autoantibodies bind to voltage gated potassium channels
neuromyotonia (Isaac’s syndrome)
outline neuromyotonia
autoantibodies that bind to the K+ channels on motor nerve endings
results in hyper excitability
function of vesimicol
inhibits storage of ACh to the vesicle
function of hemicholinium
competes with choline for uptake
name 2 neuromuscular block reversal agents and their function
neostigmine - increases junctional concentration of ACh
suggamadex
both - reversal of non-depolarising block
what are non-depolarising neuromuscular blocking agents and their function
tubocurarine
pancuronium
vecuronium
competitive ACh receptor antagonists
name depolarising neuromuscular blocking agents and their function
decamethonium
succinylcholine
mimic ACh
what is neostigmine
anticholinesterase
blocks the action of AChE
increase junctional ACh concentration
what is a cholinergic crisis
overstimulation of the NMJ leads to insensitivity to ACh
how do you cure a cholinergic crisis
atropine
what chemical group is an irreversible AChE inhibitor and how
organophosphates
phosphate covalently binds to a serine hydroxyl group in the active site of AChE
name a competitive inhibitor of AChE
edrophonium
what is physostigmine
a reversible pseudo-competitive AChE inhibitor
name an antispasmodic and its function
botulinum toxin
blocks release of ACh
