Myelin & Myelination Flashcards
What is the effect of loss of myelin
neurological disorders
What synthesises myelin
non-neuronal cells
What is the function of myelin
increase conduction velocity
What is myelin
electrical insulator
What is myelin made of
water, dry lipid, protein
Describe the appearance of myelin
banding pattern - dark and faint bands
What are the nodes of ranvier
gaps between myelin sheath
Describe the intra period line
faint
What makes up the intra period line
linked external proteins
Describe the major period line
dense
What makes up the major period line
linked internal proteins
What synthesises myelin in the CNS
oligodendrocytes
What synthesises myelin in the PNS
Schwann cells
Describe the myelination by oligodendrocytes
myelinate several parts of an axon or several axons
Describe the myelination by schwann cells
myelinate only one axon
What happens in knockout mice for cerebrosides
myelin develops vacuoles - doesn’t function properly
What symptoms are shown by cerebroside knockout mice
paralysis
what are cerebrosides
complex lipids
Where are cerebrosides located
sheaths of nerve fibres
What is the difference between CNS and PNS myelin
PNS - less cerebroside and sulfatide, CNS - more sphingomyelin
What are the CNS myelin proteins
myelin basic protein, proteo-lipid protein
What is gimpy
natural mutation affecting proteolipid proteins
What are the symptoms of gimpy
early death, loss of oligodendrocytes,
What is produced in gimpy mice
toxic mutant PLP
Where is myelin basic protein most abundant
white matter
What can myelin basic protein induce
experimental allergic encephalomyelitis
What are the PNS myelin proteins
P0, PMP22, MBP
Which is the most abundant PNS myelin
P0
What is P0
adhesion molecule - important for compaction
Defect in which PNS myelin protein causes charcot marie tooth syndrome
CMT 1b in P0
What is MS
primary demyelination autoimmune disease
What are the symptoms of MS
variable severity, relapsing/remitting, progressive
What degrades the myelin in MS
macrophages and protease activity
What is the therapy for MS
steroids, interferons, immune suppressants, stem cells
When does Guillan Barre syndrome develop
post viral/bacterial infection
Describe Guillan Barre syndrome
Acute inflammatory response triggers demyelination
How is Guillan Barre syndrome treated
intravenous immunoglobulin
