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MedNeuro Block 1 > Glial Myelination > Flashcards

Glial Myelination Flashcards

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1
Q

Define Glial cells

A

make up supporting structures of CNS and PNS

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2
Q

Glial cells out# neurons:

A

3:1 up to 10:1

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3
Q

Do glial cells have
synapses
processes
AP

A

No synpase
have processes
No AP

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4
Q

What is special about glial cells

A

retain mitotic ability into adult life

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5
Q

What is the major source of CNS cancers?

A

Gliosis–forming of glial scars: d/t maintained mitotic ability

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6
Q

What is largest and most numerous of all glia?

A

astrocytes

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7
Q

What are teh 2 major types of Astrocytes

A

Fibrous and Protoplasmic

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8
Q

Where are Fibrous astrocytes located?

What kind of processes do they have?

A

White matter

Long and thin

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9
Q

Where are Protoplasmic astrocytes located?

What kind of processes do they have?

A

Gray matter

short, thicker processes

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10
Q

What are GFAPs?

A

connective tissue of CNS

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11
Q

Funtions of astrocytes?

A 
Structure support and repair
K+ buffering
NT and metabolite removal
Have certain NT for specificity
Provide glial guides for neuronal migration during devo
In brain can serve as stem cells
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12
Q

How do Astrocyte provide support and repair of CNS?

A

GFAP act as CT of CNS
fill space and surround synapses
Engulf and degrade neuronal debris

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13
Q

How is K+ spatial buffering maintained in astrocytes?

A

while astrocyte itself is not electrically excitable, it maintins K+ gradient bc we dont’ want excessive K+… thus helps maintain membrane potential

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14
Q

How do astrocytes remove NT’s and metabolites?

A

via GLAST cycle to rapidly terminate signal. uptakes other NT’s as well

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15
Q

What is GLAST

A

glutamine-glutamate cycle
asrocytes take up excess glutamate and release it back into cell space as glutamine where it is taken up and re-synthesized into glutamate

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16
Q

What is the fnx of NT receptors on astrocytes?

A

can trigger Ca++ waves in astrocytes

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17
Q

These guys contribute to but aren’t the basis for BBB

A

astrocytes

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18
Q

How do astrocytes communicate?

A

gap junctions for glial signaling

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19
Q

What provides glial guides for neruonal migration during devo?

A

astrocytes

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20
Q

Which subset of glial cells can serve as stem cells for regeneration in the adult brain

A

astrocytes

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21
Q

Oligodendrocytes are
larger/smaller/same size as astrocytes
have fewer/more/same amt of processes
have flat/round/cuboidal nuclei

A

SMALLER
FEWER process
ROUND nuclie

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22
Q

Three types of oligos?

A

perineural
interfascicular
oligos in white matter

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23
Q

Where do oligodentrocytes myelinate?

A

CNS

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24
Q

How many axons can 1 oligo myelinate?

A

MANY axons

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25
What is a potent inhibitor of axon outgrowth and regeneration?
Central myelin
26
What are 3 types of inhibitors of CNS axonal elongation?
1. Myelin-associated glycoprotein (MAG) 2. Neurite Inhibitor of 35-dKA (NI-35) 3. Nogo gene and proteins
27
Where are MAG's expressed
by Oligodendrocytes in periaxonal oligodendorglial membrane
28
What is the significance of MAG
maintains axon-myelin complexes: axon-glial signaling
29
Levels of MAG are high in ______ and _______
developing PNS and CNS
30
Level of MAG fall in ________ but not in _________
mature PNS | not in mature CNS
31
What is the Chondroitin sulfate proteoglycan expressed by?
Neurite inhibitor of 35 kDA (NI-35)
32
What is the function of Nogo gene and proteins?
inhibit regeneration of CNS axons expressed by Oligos NOT expressed by Schwann cells
33
Where do Schwann cells myelinate?
PNS
34
How many axons do Schwann cells myelinate?
1 schwann only myelinates 1 segment of 1 axon
35
1 PNS axon is myelinated by how many Schwann cells?
50-500 cells
36
Schwann cell basal lamina: laminin is what?
Schwann cell growth promoting factors
37
Peripheral nerve regeneration requires?
laminin
38
Schwann cells surround | myelinated/unmyeliated/both axons
BOTH
39
Cell adhesion molecules such as NgCAM are what to Schwann cells
growth-promoting factor
40
What is the smallest glial cell?
Microglia
41
Microglia have long/short processes
short
42
When do microglia increase in # and size
when neurons degererate
43
When are microglia recruited?
during injury, infection and seizure
44
What disease states activate microglia?
MS, Parkinsons, Alzheimers, AIDS related dementia
45
Function of migroglia?
phagocytose debris in CNS
46
Function of Ependymal cell?
Provide some barrier btwn brain and CSF Ciliary motion helps with CSF circulation produces CSF in choroid plexus
47
Where are ependymal cells located?
line vertebral ventricles and central canal
48
Type and fnx of junctions in ependymal cells
desmosomal jnxs so some substances in CSF can penetrate the brain
49
What forms choroid plexus?
modified ependymal cells + associated caps
50
Do ependymal cells have tight junx?
YES this is the basis for BBB
51
What has myelin in both inner and outter mesaxons?
myelination in PNS: schwann cells
52
PNS/CNS has NO outer mesaxon?
CNS
53
Apposed cytoplasmic faces make up:
major dense lines
54
Apposed EXTRACELLULAR faces of myelin make up:
Minor Dense Lines
55
Diameter range cutoff for myelinated axons
less then 1 micrometer
56
Myelin has high/low lipid content | and increase/decreases or stays same with axon diameter
Increases
57
MBP is present where?
Structual protein of CNS myelin | small amount in PNS myelin
58
This guys is on the cytoplasmic face of the myelin membrane and corresponds to the major dense line
MBP
59
MBP role in autoimmune disease
basis for CNS autoimmune disease: experimental allergic encephalomyelitis
60
MAG stands for
myelin associated glycoprotein
61
MAG is present: | CNS/PNS or both
both
62
When and where does MAG decrease
in Adult in the PNS
63
MOG stands for
Myelin oligodendricyte glycoprotein
64
Where is MOG present
ONly in CNS
65
Located on surface of oligos and implicated as a target antiG in autoimmune aspect of CNS demyleinateing disease
MOGs
66
What part of Node of Ran is exposed to extracellular surface
axolemma
67
NOR has high conc of what type of voltage gated channels?
Na+
68
Internodes are usually about:
1-2 mm (larger axons = larger internodes)
69
Where does axon branching of myelinated axons occur
always at nodes
70
PNS nodes are covered by what?
Schwann cell cytoplasm
71
CNS nodes:
are bare
72
Location of Schmidt Lanterman Clefts
PNS
73
These guys are the "split" in major dense lines filled with Schwann cell cytoplasm
Schmidt Lanterman Clefts in PNS
74
Function of Schmidt Lanterman Clefts
cytoplasmic nutrients to inner clefts
75
Longitudinal incisures are located in CNS or PNS
CNS
76
Schmidt-Lanterman incisures are located in CNS or PNS
PNS
77
What are unmyelinated axons in PNS surrounded by?
Schwann cell cytoplasm and basal lamina
78
Chrnoic demyelinating disease of CNS
MS
79
Cause of MS
autoimmunde with genetic and environmetal risk factors
80
in MS what results in CNS due to demyelination
Gliosis
81
Symptoms of MS
abnormal or slowed conduction of AP disruption to BBB and acute inflammation periods of remission and relapse
82
Does MS affect sensory or motor axons?
Both--- can lead to paralysis
83
Acute inflammatory disease of PNS
Guillian Barre
84
What does GB attack?
myelin of PNS nerves for skin and muscle
85
GB is autoimmune against:
myelin proteins PO and PMP
86
What difficulties do you have with GB?
sensory perception and motor coordination

MedNeuro Block 1 (6 decks)

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