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MSS - MSK Exam 3 > Electrophysiology > Flashcards

Flashcards in Electrophysiology Deck (18):
1

myasthenia gravis

antibodies against nAChR

decreased, but not absent EPP

affects extraoccular region

ice pack test helps
-decreased acetylcholinesterase activity

2

lambert eaton myasthenic syndrome (LEMS)

association with lung cell carcinoma

3

LEMS is pre or post synaptic?

presynaptic

because it has antibodies against voltage gated calcium channels

no fusion of vesicles

enough calcium release eventually happens to cause AP
-strong contraction

4

botulin?

inhibits ACh vesicle fusion

5

hyperkalemic periodic paralysis

after exercise
and after ingesting potassium

muscle spasms and myotonia

autosomal dominant on chromosome 17 SCN4A
-problem is voltage gated sodium channels
-inactivation gate

6

what does hyperkalemia do to RMP?

becomes more positive
-bc of potassium leak channels

RMP closer to the threshold

7

what happens if you can't inactivate the sodium channels

continuous influx of sodium

continue to depolarize

keep it in a hyperexcitable state

8

what can hyperkalemia do?

can depolarize and cause inactivation gate on sodium channels

**constant absolute refractory period

9

mild depolarization 5-10

myotonia, hyperexcitability

10

greater depolarization 20-30

weakness or paralysis

11

why would carbohydrate help with depolarization problem?

sodium potassium pump

can help to fix the polarization problem

12

malignant hyperthermia

rare autosomal dominant disorder

affects the release of calcium from SR
-defective RyR

13

DHP receptors?

T tubule membrane

14

RyR receptors

SR membrane

15

why do cold temperatures help symptoms of MS?

slow voltage gated sodium channels

lengthen AP duration

16

potassium channel blockers

aka aminopyridines

prolong AP by slowing the repolarization phase

17

why does myelination increase velocity of signal?

high transmembrane resistance

18

large myelinate axion

decreased internal resitance
increased transmembrane resistance