42 - Diseases Of The Nmj & Motor Unit

Front 1

Lesions of the Soma?

Back 1

ALS
Poliomyelitis

Front 2

Lesions of Schwann Cells?

Back 2

Guillain-Barre
Diptheria

Front 3

Lesion of the Synaptic Cleft?

Back 3

Myasthenias

Front 4

Lesion of the End Plate?

Back 4

Myasthenia Gravis
nAchR Defect

Front 5

Lesion of the Muscle Fiber?

Back 5

Myotonias
Muscular Dystrophy

Front 6

Botlulism?

Back 6

Stops docking of Ach vesicles at the NMJ
Inhibits Ach exocytosis-->PARALYSIS

Front 7

Alpha-Latrotoxin?

Back 7

BLACK WIDOW
Massive Ach Release-->tetanus

Front 8

Beta-Bungarotoxin?

Back 8

SNAKE VENOM
Reduced Ach release
Acts on exocytosis

Front 9

Curare?

Back 9

ARROWHEAD POISON
Reversible nAchR antagonist-->temporary paralysis

Front 10

Lambert-Eaton Syndrome?

Back 10

Autoimmune disease
Causes insufficient release of Ach

Front 11

Signs of Lambert Eaton Syndrome?

Back 11

-Weakness improves with activity due to increasing [Ach] with continuous contractions
-Hypotonia

Front 12

Lambert Eaton Syndrome
Calcium Gluconate?

Back 12

enhances Ca2+ influx

Front 13

Lambert-Eaton Syndrome
4-AP?

Back 13

blocks K+ channels
-->increases presynaptic impulse duration
-->increased Ca2+ influx
-->improved Ach Release

Front 14

AchE Deficiency?

Back 14

-increased and prolonged EPP
-causes depolarization block

Front 15

Depolarization block?

Back 15

-Seen in AchE Deficiency & Slow Channel Syndrome
-Desensitization caused by temporal summation

Front 16

Slow Channel Syndrome?

Back 16

-Prolonged opening of the nAchR channel
-Causes prolonged depolarization-->Depolarization block
-SXS- weakness, rapid fatigue, atrophy

Front 17

Other congenital myasthenias?

Back 17

1) Abnormal binding of Ach with nAchR
2) Shortened opening times of Ach-gated channels

Front 18

Myasthenia gravis?

Back 18

-Autoimmune Ab's against nAchR
-Decreased affinity for Ach
-Weakness of voluntary muscles

Front 19

Structural changes in MG?

Back 19

1) Fewer nAchR
2) Wider Cleft
3)Smaller junctional folds

Front 20

Sxs of MG?

Back 20

-weakness improves with rest
-weakness worsens with activity
-difficulty swallowing
-lateday paralysis
Myasthenic Crisis - difficulty breathing

Front 21

Signs of MG?

Back 21

-Waning in EMG pattern
-Positive AchE test

Front 22

Treatment of MG?

Back 22

-Neostigme/Pyridostigmine-->AchE inhibitor
-Plasma Exchange
-Surgical removal of thymus

Front 23

Myotonia Congenita?

Back 23

-AD; Decreased Cl- Channels
-Slower Relaxation/Increased Excitability d/t decreased reset of Vm (from Cl- channels)

Front 24

Increased excitability in Myotonia Congenita?

Back 24

D/t unopposed action of K+ causing spontaneous depolarizations

Front 25

Sxs of Myotonia Congenita?

Back 25

-Muscle stiffness
-Hypertrophy

Front 26

Duchenne's Muscular Dystrpohy?

Back 26

-XLR
-Absence of Dystophin (muscle protein)
-Early onset muscle weakness with death by respiratory/cardiac failure

Front 27

LMN Syndrome?

Back 27

Loss of second order neurons that stimulate muscle
At motor axon or at the soma in the spinal cord or brainstem

Front 28

Causes of LMN Syndrome?

Back 28

-Poliomyelitis
-Trauma
-Degeneration

Front 29

Sxs of LMN Syndrome? WAFFA

Back 29

1) Weakness/Paralysis
2) Areflexia/Hyporeflexia
3) Fasciculations
4) Fibrillations
5) Atrophy

Front 30

Fasciculations?

Back 30

Irregular spontaneous contractions
d/t abberant firing of ALPHA motor neurons

Front 31

Fibrillations?

Back 31

Spontaneous contractions of single muscle fiber
Fetal type nAchR spreads on fiber
Hypersensitive to cations

Front 32

Poliomyelitis?

Back 32

Affects motor neurons in ventral horns
Can affect entire body
Results in paralysis and death