Normal Nerve Anatomy Flashcards
What is the mechanism of action of atracurium?
competitive inhibitor of the acetylcholine receptors on the motor endplate
How can a neuromuscular block caused by atracurium be reversed?
by giving acetylcholinesterase inhibitors
these prevent acetylcholine being broken down, increasing the concentration of acetylcholine in the synaptic cleft which reduces competitive inhibition by atracurium
What is the mechanism of action of suxamethonium?
agonises the effect of acetylcholine by binding to the nicotinic receptors on the motor end plate and causing nerve depolarisation
however suxamethonium cannot be broken down by acetylcholinesterase so there is no depolarisation and muscles are paralysed
What is the mechanism of action of botulinum?
blocks acetylcholine release by cleaving SNAP-25 a protein involved in vesicle fusion and mediating the release of the neurotransmitter
What is the general mechanism of action for non-depolarising neuromuscular blocking drugs?
competitive antagonist of ACh
don’t cause fasciculations
are not broken down (have to be reversed by adding more AchE inhibitors to increase conc. of ACh)
eg atracurium
What is the general mechanism of action for depolarising neuromuscular blocking drugs?
competitive agonist
act in addition to ACh
cause fasciculations
eg suxamethonium
What is neurapraxia?
damage to the myelin sheath, slowing nerve conduction
What is the Sunderland classification of neurapraxia?
I
What is the mechanism of action of hexamethonium?
nicotinic antagonist
What is the mechanism of action of curare toxin?
Inhibition of nicotinic acetylcholine receptors at motor end plates, preventing the movement of the respiratory muscles
What is the description of Sunderland classification IV?
loss of axonal, endoneurial and perineural continuity
no conduction
What is the definition of neurotmesis?
severed nerve fibre, no conduction
What is Wallerian degeneration?
when a nerve fibre distal to the injury degenerates
