Valley Physiology of the Neuron Flashcards
Stimulation of presynaptic and postsynaptic nicotinic receptors at the neuromuscular junction leads to which of these responses?
(increased/decreased) release of acetylcholine
(increased/decreased) motor endplate potential
increased release of acetylcholine
decreased (depolarized) motor end plate potential
How many molecules of acetylcholine are required to open a channel of the motor end-plate?
2
Sodium, calcium, and potassium ions diffuse in which directions when the channels of the motor end-plate of skeletal muscle are stimulated to open?
sodium moves inward
calcium moves inward
potassium moves outward
The release of acetylcholine from the neuromuscular junction will be increased in which of the following conditions?
- Hyponatremia
- Hypocalcemia
- Hypomagnesemia
- Hypokalemia
Hypomagnesemia
The presynaptic action of succinylcholine does what to the postsynaptic action?
- Enhances
- Antagonizes
- No change
Succinylcholine antagonizes it’s postsynaptic action.
What NDMR is associated with dose-dependent histamine release?
atracurium
Which agent has antimuscarinic actions?
- Succinylcholine
- Pancuronium
- Mivacurium
- D-Tubocurarine
Pancuronium
What electrolyte abnormality is a potential adverse effect of succinylcholine administration?
Hyperkalemia
What is the earliest sign of malignant hyperthermia?
Increase in end-tidal CO2
When you use a nerve-muscle stimulator on the right wrist of a patient paralyzed on the right side, what will you see during a train-of-four?
Greater amplitude of twitches on the right compared with the left d/t exntrajunctional receptors.
What will happen to a non-depolarizing neuromuscular blockade if the patient receives neomycin during the case? A depolarizing blockade?
They will both increase.
What will you see with the nerve-muscle stimulator if the patient has been given a non depolarizing neuromuscular relaxant?
Fade on train-of-four and post-titanic potentiation
It is best to reverse non depolarizing neuromuscular blockade when there are how many twitches in the train-of-four?
Four (controversial)
I believe in class we were told 2-3, leaning towards 3
Non depolarizing neuromuscular blockade is increased by each of the following EXCEPT:
- isoflurane
- penicillin
- lidocaine
- lithium
penicillin
What happens to the number of nicotinic receptors in skeletal muscle in a patient with a spinal cord injury?
The number increases in denervated skeletal muscle.
A patient with biliary disease is given vecuronium. How will the vecuronium be eliminated?
through both metabolism (biliary metabolism) and renal elimination
Cisatracurium is eliminated how?
Hofmann elimination
With a non depolarizing block, DBS3,3 produces what type of twitches?
2 unequal (fading) twitches
A vital capacity of at least 20 ml/kg occurs when what percentage of neuromuscular receptors are blocked?
75%
At the neuromuscular junction, does the pre-synaptic action of succinylcholine enhance or antagonize its post-synaptic action?
Succinylcholine, by stimulating the pre-synaptic nicotinic receptor, AUGMENTS the release of ACh. Since the released ACh opens channels and depolarizes the motor end-plate like succinylcholine, the pre-synaptic action of succinylcholine ENHANCES its post-synaptic action.
If you use a nerve-muscle stimulator on the right wrist of the patient with right-sided hemiplegia, will the twitch be less than, the same as, or greater than the twitch on the left?
The twitch on the right will be greater than the left! Nicotinic receptors are up-regulated on the right, hemiplegic side.
Why isn’t cardiac muscle directly involved in malignant hyperthermia?
Because cardiac myocytes (muscle fibers) express the RyR2 isoform of the ryanodine receptor INSTEAD of the RyR1 receptor found embedded in the sarcoplasmic reticulum of skeletal muscle.
