Neuromuscular Blockers Flashcards
(19 cards)
What neurotransmitter is primarily involved at the neuromuscular junction?
Acetylcholine
Acetylcholine (ACh) is crucial for muscle activation at the neuromuscular junction.
What type of receptor does acetylcholine bind to at the neuromuscular junction?
Nicotinic receptor
The nicotinic acetylcholine receptor (nACh) contains 5 subunits and is responsible for fast synaptic transmission.
What are the two main types of neuromuscular blockers based on their mechanism of action?
- Non-depolarising
- Depolarising
What is a primary clinical application of neuromuscular blockers?
- Surgery
- Intubation
What is the role of acetylcholine esterase at the neuromuscular junction?
Rapidly breaks down acetylcholine
Acetylcholine esterase hydrolyzes ACh into choline and acetate, terminating neurotransmission.
What does the influx of Na+ ions into the muscle cell cause?
Depolarization
This depolarization leads to the end-plate potential in skeletal muscle.
What is the effect of neuromuscular blockers on consciousness?
They do not affect consciousness
Neuromuscular blockers cause motor paralysis but do not impair awareness.
What is an example of a non-depolarising neuromuscular blocker?
Curare
Curare is derived from South American plants and causes paralysis by blocking ACh at the NMJ.
What is the mechanism of action for non-depolarising neuromuscular blockers?
Competitive antagonism of ACh at the motor end plate
How can non-depolarising neuromuscular blockade be reversed?
By acetylcholine esterase inhibitors
An example is neostigmine, which increases ACh levels at the NMJ.
What is the primary effect of depolarising neuromuscular blockers?
Maintained depolarization of the muscle
This leads to paralysis due to the inability of the muscle to respond to ACh.
What is a significant side effect of Suxamethonium?
- Bradycardia
- Tachycardia
- Muscle pain
- Hyperkalemia
- Increased intracranial tension
What occurs during Phase I depolarisation block?
Loss of membrane potential in the postsynaptic cell
The muscle fiber no longer responds to ACh stimulation.
What happens during Phase II depolarisation block?
Receptor desensitisation occurs
This is due to persistent activation and leads to internalisation of the receptor.
What is the onset time for Suxamethonium?
5-10 minutes
What is the duration of action for Vecuronium?
2-3 minutes
True or False: Non-depolarising neuromuscular blockers require 70-80% of receptors to be blocked for transmission to fail.
True
What type of drug is Tubocurarine?
Non-depolarising neuromuscular blocker
Tubocurarine was isolated from plant extracts and replaced by synthetic drugs.
What is the primary route of administration for neuromuscular blockers?
IV injection
