6: Neuromuscular disorders Flashcards Preview

Neurology Week 5 2018/19 > 6: Neuromuscular disorders > Flashcards

Flashcards in 6: Neuromuscular disorders Deck (63)
Loading flashcards...
1

What is the neuromuscular junction?

Synapse between LMNs and muscle fibres

2

Which horn of the spinal cord contains motor neurons?

Anterior (ventral horn)

3

What is a motor end plate?

The muscle-end of the neuromuscular junction

4

Each motor neuron may supply (one / many) muscle(s).

Each muscle is supplied by (only one / many) motor neuron(s).

many

only one

5

Which neurotransmitter passes into the synaptic cleft of the NMJ in response to an action potential?

ACh

6

Which ions are involved in the wave of depolarisations along a nerve axon?

Na+ IN

K+ OUT

7

Which ion triggers the release of neurotransmitter into the synaptic cleft of the NMJ?

Ca2+

8

Which enzyme clears up remaining ACh from the synaptic cleft?

Acetylcholinesterase

9

Which toxin occupies ACh receptors in the synaptic cleft, preventing muscle contraction?

Tubocurarine 

'flying death', poison arrows etc.

10

Which receptor is blocked by tubocurarine?

What happens as a result?

ACh receptor

Muscle paralysis (inc. respiratory)

11

Which poison inhibits acetylcholinesterase, causing muscle paralysis and death?

Novichok

12

What cannot be released if there is a problem with the Ca2+ channels of the pre-synaptic neurons involved in NMJs?

ACh

13

What is botulism?

Infection by Clostridium botulinum

Which produces Botulinum toxin

14

What is the effect of botulinum toxin?

Why?

Muscle weakness

Blocks ACh release at pre-synaptic terminal

15

How do the following nerve agents affect the neuromuscular junction?

a) tubocurarine

b) NOVICHOK

c) Botulinum toxin?

a) ACh receptor antagonists

b) Acetylcholinesterase inhibitor

c) Blocks secretion of ACh at pre-synaptic terminal

16

Name an autoimmune disease which affects the neuromuscular junction at the

a) post-synaptic

b) pre-synaptic end?

a) Myaesthenia gravis

b) Lambert-Eaton syndrome

17

What is the main symptom of Lambert-Eaton syndrome?

Muscle weakness

18

What condition is Lambert-Eaton syndrome associated with?

Small cell lung cancer

19

What antibodies are produced in Lambert-Eaton syndrome?

Ca2channel antibodies

So not as much ACh is released into NMJ, causing muscle weakness

20

The drug 3-4-diaminopyridine is used to treat symptoms of Lambert-Eaton syndrome.

How does it work?

Blocks Kchannels

So action potential lasts for longer, more Ca2+ has the chance to enter the pre-synaptic terminal and more ACh can be secreted into the NMJ

21

What is a rare post-synaptic disorder causing muscle weakness and fatigue?

Myaesthenia gravis

22

Myaesthenia gravis is an ___ disease.

autoimmune

23

When does the incidence of myaesthenia gravis peak?

Early 20s

Elderly

24

What is the pathophysiology of myaesthenia gravis?

Autoimmune disease

Autoantibodies BIND TO ACh receptors of neuromuscular junction

Resulting in muscle weakness and fatigability

25

Which antibodies are seen in 90% of patients with myaesthenia gravis?

ACh receptor antibodies

26

Which immune organ undergoes hyperplasia in myaesthenia gravis?

Thymus

Particularly in young people

27

(Men / women) tend to develop myaesthenia gravis.

Women

autoimmune disease

28

What is the course of weakness seen in myaesthenia gravis?

Fluctuating

29

Which muscles tend to be affected in myaesthenia gravis?

Extraocular muscles

Facial muscles

Bulbar muscles (chewing, speaking, swallowing)

30

What tends to cause death in late myaesthenia gravis?

Respiratory muscle weakness