Neuromuscular Junction Dysfunction Flashcards Preview

MOHD4: Exam 5 > Neuromuscular Junction Dysfunction > Flashcards

Flashcards in Neuromuscular Junction Dysfunction Deck (18)
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1
Q

____ influx causes vesicle docking and ACh release

A

Calcium

2
Q

Excess ACh in the NMJ leads to

A

over stimulation of muscle: twitching, cramping, myalgias

3
Q

Pre-synaptic diseases

A

LEMS, Botulism

4
Q

ACh interacting with post-synaptic receptors causes _________ and depolarization

A

Na influx

5
Q

Possible causes of excess ACh:

A

Congenital myasthenic syndrome
Organophosphate toxicity
Pyridostigmine
Any drug causing AChE inhibition

6
Q

Most common LEMS cancer association

A

small cell lung cancer

7
Q

Muscle membrane depolarization

A

Endplate Potential (EPP)

8
Q

Binds presynaptic membrane, taken up into nerve terminals, splits into heavy/light chain, light chain cleaves SNARE protein, vesicles cannot release ACh

A

Botulism Toxin

9
Q

Safety factor =

A

EPP is higher than threshold

10
Q

Myasthenia Gravis mechanism

A

Decreased response to ACh release –> less Na influx –> less depolarization –> loss of safety factor –> fatiguable weakness

11
Q

Lack of Acetylcholine (anticholinergic effects)

A

weakness, ptosis, GI dysfunction, urinary retention, hypohidrosis, blurred vision

12
Q

Icepack or Tensilon induce

A

improvement of muscle response (inhibit acetylcholinesterase)

13
Q

Antibodies to IgG attack the ____________ in Myesthenia gravis

A

post-synaptic AChR

14
Q

Acetylcholinesterase inhibitor

A

pyridostigmine –> Myasthenia gravis, LEMS treatment

15
Q

Organophosphate Toxicity results in ________ NMJ dysfunction

A

Synaptic

16
Q

Clinical Presentation: proximal muscle weakness (esp legs), gets better after brief exercise

A

Lambert-Eaton Myasthenic Syndrome (LEMS)

often paraneoplastic

17
Q

How does exercise improve LEMS muscle response?

can also be repetitive shocks

A

Increased muscle firing, accumulation of small amounts of Ca, increased ACh vesicle docking/release

18
Q

Common causes of later onset Botulism disease?

A

Foodborne
Wound
Iatrogenic (local injection)
Inhalation