Neuromuscular Junction Flashcards
Which NT is involved in neuromuscular junctions & what receptor us involved in muscle contraction?
ACh
Nicotinic ACh rec
What is an end plate region?
When a nerve fibre branch attaches to muscle
What enzyme converts AcCoA + Choline ➡️ Ach?
Choline Acetylcholinesterase
What type of channel is the nicotinic receptor?
A ligand gated ion channel
Ionotropic
Where is Acetylcholinesterase found?
On muscle, right next to the nicotinic receptors
What ions flows in when nicotinic receptor channels open?
Na+
What is an AP called in muscle with a small influx of sodium through nicotinic receptors?
A mini end plate potential
What does the MEPP open?
Voltage gated sodium channels, large influx of sodium, causes EPP.
What ion negatively modulates calcium channels?
Mg2+
What is lost in myasthenia gravis?
Nicotinic receptors (autoimmune disease)
MG treatment
Neostigmine
Pyridostigmine
Medium duration
Inhibit Acholinesterase
MG diagnosis
Edrophonium
Short duration
What neuromuscular blocker is used to anaesthetise a patient with a full stomach?
Suxamethonium
Agonist to Ach
Works in 1 min - fast!
Non- depolarising blocking agents (antagonists) have a ……. duration of action than depolarising (agonist) agents
Longer
Name egs of non depol blocking agents/ agonists
Vecuronium
Atricurium
Mivacurium
Take 3-4 mins to work
What does atricurium cause to be released?
Histamine
How does atricurium leave the body?
Hoffman elimination =
Spontaneous degradation
Name the 1 depolarising blocker (agonist)
How is it different to non-depolarising blockers?
Suxamethonium
Takes 1 min to work
Has shorter duration of action
What would you switch too after the patient in emergency surgery with a full stomach is intubated using Suxamethonium?
Non depolarising blocking agents
Eg vecuronium
How long can Suxamethonium stay near the receptor before it is broken down?
10 mins
Ach broken down much quicker
Side effect of depolarising blockers
Hyperkalaemia
⬆️ K+
Leads to cardiac arythmias
Side effect of depolarising blocker Suxamethonium
Parasympathetic effects- bradycardia, inc bronchial & saliva secretion
Malignant hyperpyrexia- inc body temp (v rate)
Prolonged paralysis
Who can you not give Suxamethonium?
People on antichilinesterases
