NUR 751 NMBD, Anticholinesterase &
Anticholinergics–Questions and Answers | 2026
Update | 100% Correct.
what acetylcholine peptide is present in fetal but not adult?
fetal= gamma
adult= epsilon
acetylcholine receptor has 5 peptides
-2 alpha
-beta
-epsilon
-delta
magnitude of potential is directly related to ______?
amount of Ach released
what are the two peptide formations in extrajunctional nicotinic receptors?
5 alpha units or 2 alpha, 1 beta, 1 gamma, 1 delta
when are extrajunctional nicotinic receptors present?
present in fetal development or can be reactivated with denervation injury and prolonged
immobility
MOA for depolarizing neuromuscular blocker
,attaches to one or both alpha subunits of nicotinic acetylcholine receptor --> depolarization of the
postsynaptic membrane--> depolarization spreads to adjacent muscles causing contraction
what is a phase 1 block?
-this is the expected block from succ
-decreased contraction in response to single twitch stimulation, TOF greater than 0.7
-decreased amplitude but sustained response to continuous stimulation
-absence of post-tetanic facilitation
explain augmentation of block after administration of anticholinesterase
-giving neostigmine then giving succ
-neostigmine prevents the breakdown of Ach, there is more Ach in the synapse
-increases depolarization-->prolongs the block
upregulation of extrajunctional receptors causes what in non-depolarizing neuromuscular
blockers?
resistance
patients with upregulation of extrajunctional receptors are resistant to non-depolarizers
more receptors = more NDMR to antagonize all receptors
what is a phase 2 block?
-desensitizing block
-transition from phase 1 to phase 2 is abrupt
, -occurs with high succ doses 2-4 mg/kg IV drip
-onset usually manifested initially as tachyphylaxis
-block will resemble a non-depolarizing block, will have fade
what is tachyphylaxis
need to increase infusion rate or administer progressively larger doses
what can antagonize a phase 2 block?
-anticholinesterase
-based on TOF, start with small dose edrophonium
-if reversal noted, giving more will likely resolve the block
-or you may just have to ventilate, sedate and wait
how quickly does laryngeal recovery take after giving succ?
about 4 min
explain how succ is eliminated
-hydrolysis bu plasma cholinesterases
- AKA pseudocholinesterase or false cholinesterase or type 2 cholinesterase or
butyrylcholinesterase
-rapid metabolism--only 10% of injected dose actually reaches the NMJ
what drugs does plasma cholinesterase metabolize
-succ
-mivacurium
-procaine
Anticholinergics–Questions and Answers | 2026
Update | 100% Correct.
what acetylcholine peptide is present in fetal but not adult?
fetal= gamma
adult= epsilon
acetylcholine receptor has 5 peptides
-2 alpha
-beta
-epsilon
-delta
magnitude of potential is directly related to ______?
amount of Ach released
what are the two peptide formations in extrajunctional nicotinic receptors?
5 alpha units or 2 alpha, 1 beta, 1 gamma, 1 delta
when are extrajunctional nicotinic receptors present?
present in fetal development or can be reactivated with denervation injury and prolonged
immobility
MOA for depolarizing neuromuscular blocker
,attaches to one or both alpha subunits of nicotinic acetylcholine receptor --> depolarization of the
postsynaptic membrane--> depolarization spreads to adjacent muscles causing contraction
what is a phase 1 block?
-this is the expected block from succ
-decreased contraction in response to single twitch stimulation, TOF greater than 0.7
-decreased amplitude but sustained response to continuous stimulation
-absence of post-tetanic facilitation
explain augmentation of block after administration of anticholinesterase
-giving neostigmine then giving succ
-neostigmine prevents the breakdown of Ach, there is more Ach in the synapse
-increases depolarization-->prolongs the block
upregulation of extrajunctional receptors causes what in non-depolarizing neuromuscular
blockers?
resistance
patients with upregulation of extrajunctional receptors are resistant to non-depolarizers
more receptors = more NDMR to antagonize all receptors
what is a phase 2 block?
-desensitizing block
-transition from phase 1 to phase 2 is abrupt
, -occurs with high succ doses 2-4 mg/kg IV drip
-onset usually manifested initially as tachyphylaxis
-block will resemble a non-depolarizing block, will have fade
what is tachyphylaxis
need to increase infusion rate or administer progressively larger doses
what can antagonize a phase 2 block?
-anticholinesterase
-based on TOF, start with small dose edrophonium
-if reversal noted, giving more will likely resolve the block
-or you may just have to ventilate, sedate and wait
how quickly does laryngeal recovery take after giving succ?
about 4 min
explain how succ is eliminated
-hydrolysis bu plasma cholinesterases
- AKA pseudocholinesterase or false cholinesterase or type 2 cholinesterase or
butyrylcholinesterase
-rapid metabolism--only 10% of injected dose actually reaches the NMJ
what drugs does plasma cholinesterase metabolize
-succ
-mivacurium
-procaine
