Myelin and Myelination Flashcards

1
Q

Myelin

A
  • Lipid-rich
  • Synthesised by non-neuronal cell
  • Increases conduction velocity
  • Loss of myelin produces neurological disorders
  • Myelin may alter in learning and memory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What percentage of dry weight of white matter is myelin?

A

50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where does myelin come from in the PNS?

A

Schwann cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where does myelin come from in the CNS?

A

Oligodendrocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Schwann cells myelinate _____ axons

A

Individual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Oligos myelinate ______ axons/parts of axons

A

Several

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does myelin look like?

A

Protein - lipid - protein repeats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the periodicity of myelin in the PNS?

A

11.9 nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the periodicity of myelin in the CNS?

A

10.7 nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What percentage of myelin is water?

A

~40%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What percentage of myelin is dry lipid?

A

70-85%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What percentage of myelin is protein?

A

15-30%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is myelin made of?

A
  • Water
  • Dry lipid
  • Protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

PNS has less…

A
  • Cerebroside

- Sulfatide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

CNS has more…

A

Sphingomyelin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

CNS myelin proteins

A
  • Myelin basic protein (MBP)

- Proteolipid protein (PLP)

17
Q

Proteolipid protein (PLP)

A
  • Important role in formation or maintenance of myelin

- Mutation causes Jimpy mouse

18
Q

Myelin basic protein (MBP)

A
  • Important in myelination of nerves
  • Induces experimental allergic encephalomyelitis (EAE)
  • Implicated in MS
19
Q

Other CNS myelin proteins

A

Enzymes

  • Cyclic nucleotide phosphodiesterase
  • Proteases
  • Lipid metabolism
  • Carbonic anhydrase

Ig-like molecules

  • MOG and MAG
  • Oligo-axon communication
20
Q

PNS myelin proteins

A
  • P0
  • MBP
  • PMP-22
21
Q

P0

A

50+% of PNS myelin

22
Q

MBP in PNS

A

Less important than in CNS

23
Q

PMP-22

A

Alterations in gene expression associated with Charcot-Marie-Tooth 1a?

24
Q

Multiple Sclerosis

A
  • Onset 20s - 40s
  • Variable severity
  • May be progressive
  • Plaques shown in MRI
  • Primary demyelination
25
Q

What type of white matter is vulnerable in MS?

A

Periventricular white matter

26
Q

What is the percentage concordance of monozygotic twins with MS?

A

30%

27
Q

What causes MS?

A
  • Geographic distribution suggests environment, vitamin D

- Virally - herpes virus

28
Q

What race is MS more common in?

A

Caucasians

29
Q

What type of disease is MS?

A

Auto-immune

No clear evidence for particular auto-antigen

30
Q

What degrades myelin in MS?

A

Macrophage and protease activity

31
Q

Therapy for MS

A
  • Steroids
  • Interferons
  • Cyclophosphamide, antibodies (immune su-pressants)
  • Haemopoietic stem cells
  • Vitamin D
32
Q

Guillan-Barre Syndrome

A
  • Post viral/bacterial infection
  • Acute inflammatory response
  • Primary demyelination
  • LPS of bacterial cell coat and myelin lipids/proteins molecular mimicry
33
Q

Guillan-Barre Syndrome symptoms

A
  • Numbness
  • Pain
  • Muscle weakness
  • Balance/coordination problems
  • Pins and needles
34
Q

Guillan-Barre Syndrome treatment

A
  • IV immunoglobulin

- Plasma exchange - plasmapheresis

35
Q

Multiple sclerosis symptoms

A
  • Fatigue
  • Vision problems
  • Numbness/tingling
  • Mobility problems
  • Sexual problems
  • Problems with thinking, learning and planning