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MedNeuro Block 1 > Glial Myelination > Flashcards

Glial Myelination Flashcards

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
Q

What is a potent inhibitor of axon outgrowth and regeneration?

A

Central myelin

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26
Q

What are 3 types of inhibitors of CNS axonal elongation?

A
  1. Myelin-associated glycoprotein (MAG)
  2. Neurite Inhibitor of 35-dKA (NI-35)
  3. Nogo gene and proteins
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27
Q

Where are MAG’s expressed

A

by Oligodendrocytes in periaxonal oligodendorglial membrane

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28
Q

What is the significance of MAG

A

maintains axon-myelin complexes: axon-glial signaling

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29
Q

Levels of MAG are high in ______ and _______

A

developing PNS and CNS

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30
Q

Level of MAG fall in ________ but not in _________

A

mature PNS

not in mature CNS

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31
Q

What is the Chondroitin sulfate proteoglycan expressed by?

A

Neurite inhibitor of 35 kDA (NI-35)

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32
Q

What is the function of Nogo gene and proteins?

A

inhibit regeneration of CNS axons
expressed by Oligos
NOT expressed by Schwann cells

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33
Q

Where do Schwann cells myelinate?

A

PNS

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34
Q

How many axons do Schwann cells myelinate?

A

1 schwann only myelinates 1 segment of 1 axon

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35
Q

1 PNS axon is myelinated by how many Schwann cells?

A

50-500 cells

36
Q

Schwann cell basal lamina: laminin is what?

A

Schwann cell growth promoting factors

37
Q

Peripheral nerve regeneration requires?

A

laminin

38
Q

Schwann cells surround

myelinated/unmyeliated/both axons

A

BOTH

39
Q

Cell adhesion molecules such as NgCAM are what to Schwann cells

A

growth-promoting factor

40
Q

What is the smallest glial cell?

A

Microglia

41
Q

Microglia have long/short processes

A

short

42
Q

When do microglia increase in # and size

A

when neurons degererate

43
Q

When are microglia recruited?

A

during injury, infection and seizure

44
Q

What disease states activate microglia?

A

MS, Parkinsons, Alzheimers, AIDS related dementia

45
Q

Function of migroglia?

A

phagocytose debris in CNS

46
Q

Function of Ependymal cell?

A

Provide some barrier btwn brain and CSF
Ciliary motion helps with CSF circulation
produces CSF in choroid plexus

47
Q

Where are ependymal cells located?

A

line vertebral ventricles and central canal

48
Q

Type and fnx of junctions in ependymal cells

A

desmosomal jnxs so some substances in CSF can penetrate the brain

49
Q

What forms choroid plexus?

A

modified ependymal cells + associated caps

50
Q

Do ependymal cells have tight junx?

A

YES this is the basis for BBB

51
Q

What has myelin in both inner and outter mesaxons?

A

myelination in PNS: schwann cells

52
Q

PNS/CNS has NO outer mesaxon?

A

CNS

53
Q

Apposed cytoplasmic faces make up:

A

major dense lines

54
Q

Apposed EXTRACELLULAR faces of myelin make up:

A

Minor Dense Lines

55
Q

Diameter range cutoff for myelinated axons

A

less then 1 micrometer

56
Q

Myelin has high/low lipid content

and increase/decreases or stays same with axon diameter

A

Increases

57
Q

MBP is present where?

A

Structual protein of CNS myelin

small amount in PNS myelin

58
Q

This guys is on the cytoplasmic face of the myelin membrane and corresponds to the major dense line

A

MBP

59
Q

MBP role in autoimmune disease

A

basis for CNS autoimmune disease: experimental allergic encephalomyelitis

60
Q

MAG stands for

A

myelin associated glycoprotein

61
Q

MAG is present:

CNS/PNS or both

A

both

62
Q

When and where does MAG decrease

A

in Adult in the PNS

63
Q

MOG stands for

A

Myelin oligodendricyte glycoprotein

64
Q

Where is MOG present

A

ONly in CNS

65
Q

Located on surface of oligos and implicated as a target antiG in autoimmune aspect of CNS demyleinateing disease

A

MOGs

66
Q

What part of Node of Ran is exposed to extracellular surface

A

axolemma

67
Q

NOR has high conc of what type of voltage gated channels?

A

Na+

68
Q

Internodes are usually about:

A

1-2 mm (larger axons = larger internodes)

69
Q

Where does axon branching of myelinated axons occur

A

always at nodes

70
Q

PNS nodes are covered by what?

A

Schwann cell cytoplasm

71
Q

CNS nodes:

A

are bare

72
Q

Location of Schmidt Lanterman Clefts

A

PNS

73
Q

These guys are the “split” in major dense lines filled with Schwann cell cytoplasm

A

Schmidt Lanterman Clefts in PNS

74
Q

Function of Schmidt Lanterman Clefts

A

cytoplasmic nutrients to inner clefts

75
Q

Longitudinal incisures are located in CNS or PNS

A

CNS

76
Q

Schmidt-Lanterman incisures are located in CNS or PNS

A

PNS

77
Q

What are unmyelinated axons in PNS surrounded by?

A

Schwann cell cytoplasm and basal lamina

78
Q

Chrnoic demyelinating disease of CNS

A

MS

79
Q

Cause of MS

A

autoimmunde with genetic and environmetal risk factors

80
Q

in MS what results in CNS due to demyelination

A

Gliosis

81
Q

Symptoms of MS

A

abnormal or slowed conduction of AP
disruption to BBB and acute inflammation
periods of remission and relapse

82
Q

Does MS affect sensory or motor axons?

A

Both— can lead to paralysis

83
Q

Acute inflammatory disease of PNS

A

Guillian Barre

84
Q

What does GB attack?

A

myelin of PNS nerves for skin and muscle

85
Q

GB is autoimmune against:

A

myelin proteins PO and PMP

86
Q

What difficulties do you have with GB?

A

sensory perception and motor coordination

MedNeuro Block 1 (6 decks)

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