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► Med - Year 1 > Glia > Flashcards

Glia Flashcards

1
Q

Ratio of glia:neuron

A

10:1

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2
Q

Resident macrophages of the brain

A

Microglia

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3
Q

Glia cell that makes myelin in PNS

A

Schwann cells

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4
Q

Glia cell that make myelin in CNS

A

Oligodendrocytes

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5
Q

Neural tube origin (3)

A

Oligodendrocytes, Astrocytes, and neurons

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6
Q

Neural crest origin (1)

A

Schwann cell

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7
Q

(Oligo/Schwan cells) can differentiate without neuronal signals, while (oligo/schwann cell) needs neuronal signals to differentiate

A

Oligos don’t need signal, schwann need signal

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8
Q

Myelin is an extension of?

A

Plasma membrane of schwann cells/ oligodendrocytes

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9
Q

Which cell (and where) can insulate up to 40 different axon segments?

A

Oligos, in CNS

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10
Q

Which cell (and where) can insulate ONLY ONE axon segment?

A

Schwann cell, in PNS

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11
Q

These cells form Remak bundles around neurons

A

Non-myelinating Schwann cells (Sensory C-fibers)

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12
Q

Molecular architecture of compact myelin consist of these two lines

A 
Intraperiod lines (between membranes, external layer)
Major dense lines (membrane, cytoplasmic part)
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13
Q

This protein holds internal surfaces together and seal up the major dense lines

A

Myelin basic protein (MBP)

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14
Q

This protein involved in keeping myelin sheath compact is only found in CNS

A

PLP

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15
Q

This protein involved in keeping myelin sheath compact is only found in PNS

A

PMP22

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16
Q

This lipid has a major role in keeping myelin compact

A

Glycosphingolipids (GSL)

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17
Q

Mutations in these components of compact myelin result in many different disorders

A

PLP - Pelizaeus Merzbacher Disease
PMP22, P0, Cx32 - Charcot marie Tooth Disease
GSL- Leukodystrophies (lipid storage diseases)

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18
Q

What is the percent composition of lipid and protein in CNS myelin? How does this compare to entire brain?

A

CNS myelin- 70% lipid, 30% protein

Whole brain- lipid

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19
Q

Channels that transverse through myelin

A

Schmidt-Lanterman cleft

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20
Q

Site of myelin attachment to the axon, found next to Nodes of Ranvier, where myelin loops get attached

A

Paranodal region

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21
Q

In addition to Schwann cells, what else covers some of myelin in PNS?

A

Microvilli

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22
Q

There are no microvilli present in CNS; what instead covers the nodal region?

A

Astrocytes, function still unclear

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23
Q

Three important molecules that are important in myelin-axon interaction. What happens if these are removed?

A

Caspr, Lipids, NF155.

If ands not formed, paranodes to not form resulting in bad connection with neurons. Shaking

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24
Q

In addition to increasing nerve conduction velocity and saltatory conduction (propagation of action potential), what are two other functions of myelin?

A
  1. Bi-directional signaling

2. Inhibits axon regeneration (CNS myelin) - not good!

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25
Q

Glia to neuron interaction

A

Bi-directional signaling

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26
Q

Two things that inhibit regernation of axons in CNS

A
  1. degenerating myelin- produce inhibitory signals

2. Astrocytes- come in and make scars

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27
Q

Lack of axon regeneration is a major problem in these type of injuries

A

Spinal cord injury,

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28
Q

Why can a cut axon in the PNS regenerate axons?

A

Myelin gets cleared up efficiently, Schwann cells produce growth promoting signals

29
Q

Why can Schwann cells help regenerate axons while oligos cannot?

A

Schwann cells have the capacity to re-differnetiate into progenitor cells if get damaging signals, can produce growth factors and make myelin and help regenerate axons. Oligos don’t have this ability and just die.

30
Q

Why is multiple sclerosis not just a disease of myelin?

A

Huge axonal component, in later stages, it’s irreversible situation, because cannot regenerate axons even if can figure out how to make myelin.

31
Q

Briefly describe course of MS progession

A

Cycles between relapse and remission, increasing disability with each cycle

32
Q

In MS, conduction is temporarily restored. What is the explanation for this?

A

Conduction restored by increase in density of sodium channels. But eventually, axons die, and there is a prominent conduction loss

33
Q

During demyelination, oligos die. What cells migrate from other regions and proliferate and differentiate into oligos to help remyelinate?

A

Oligodendrocyte progenitor cells (OPCs)

34
Q

Two possible explanations for remyelination failure

A
  1. Failure of OPC recruitment

2. Failure of OPC differentiation

35
Q

4 types of Glia

A
  1. Astrocytes
  2. Oligodendrocytes
  3. Polydendrocytes
  4. *microglia

*immune cell, not derived from neural progenitor

36
Q

Oligos and astrocytes come from what cell

A

Neuroepithelial stem cells (which can also go to form neurons)

37
Q

This cell makes up what percent of cellular volume of CNS, and what percent of total cell number

A

90% of CNS cell volume, 50% of total cell number

38
Q

Astrocytes are identified by what 3 cell-specific proteins?

A

GFAP (glial fibrillary acidic protein), vimentin, S100Beta

39
Q

Process where never cells are damaged and killed by excessive neurotransmitter stimulation

A

excitoxicity

40
Q

These astrocyte-secrete proteins help regulate synaptogenesis

A

hevin, SPARC

41
Q

Gliotransmitter

A

chemicals released from glial cells that help neuronal communication between neurons and other glial cells (indistinguishable from neurotransmitters)

42
Q

Astrocytes are the intermediate in this relationship between the neuronal activity and local blood flow changes

A

Neurovascular coupling

43
Q

True/False: Astrocytes regulate sleep

A

True

44
Q

Tripartite synapse

A

Astrocytes are key player in chemical communication between 2 neurons

  1. pre synaptic
  2. post synaptic
  3. astrocyte- can absorb and emit neurotransmiters
45
Q

How do astrocytes play role in blood pressure?

A

Have feet on blood vessel in addition to feet on pre and post synaptic terminals

46
Q

Astrocytes can secrete these two substances that will lead to different activities of neuronal cell due to change in what intracellular levels?

A

Adenosine/ADP or glutamate, change in intracellular calcium levels

47
Q

Astrocytes assist brain and protects harm caused by

A

inflammation

48
Q

When glial cells function improperly, present as neurodegenerative disease

A

Gliodystrophy

49
Q

Lou Gehrig’s disease

A

ALS (amyotrophic lateral sclerosis)

50
Q

ALS

A

Upper and lower motor neuron degeneration, symptoms include muscle twitching, weakness, stiffness, cramping, clumsiness, muscle atrophy

51
Q

3 ways astrocytes can mediate neurotoxicity (role of astrocytes in ALS)

A
  1. failure to provide trophic support
  2. react to and amplify neural dysfunction
  3. produce neurotoxins (start pumping out toxins that will kill motorneurons
52
Q

In experiment when extracted astrocytes from mouse with ALS, astrocytes were toxic to what?

A

All motorneurons

53
Q

ALS is a neurodegenerative disease, but it is CAUSED by

A

astrocytes (secrete factors toxic to motorneurons-kill them)

54
Q

Microglia can be identified by these three cell-specific proteins

A

Iba-1, CD11b, CD45

55
Q

Microglia originate from this region

A

Bone marrow

56
Q

Fate mapping analysis reveals that adult microglia derive from

A

primitive macrophages

57
Q

True or false: Microglia function like macrophages, and have the same role as macrophages.

A

FALSE. They function like macrophages, but have unique roles from macrophages. They are a specialized cell type to the BRAIN.

58
Q

What happens to microglia when activated?

A

Change shape, proliferate, and migrate. Very motile to monitor environemnt

59
Q

Globoid cell Leukodystrophy

A

Malignant microglia, genetic disease in mutation to form myelin, microglia are hyperactive, excessively chew up oligos

60
Q

Activated microglia have (same/different) proteins than cells that are “quiet”

A

Different proteins. Can use MRI and PET to see areas of brain that have heightened levels of microglial activity

61
Q

This brain structure has an important link to Parkinson’s disease

A

Substantia nigra- see very active microglia in someone with parkinsons

62
Q

Area of brain that plays important role in reward, addiction, and movement

A

Substantia nigra

63
Q

Parkinson’s disease is characterized by death of this

A

dopaminergic neurons

64
Q

What would a MAO deficiency cause high levels of?

A

Catecholamines (monoamine oxidase is responsible for degradation)

65
Q

Flight or fight response

A

Catecholamines

66
Q

Microglial activity corresponds with the location of what?

A

Brain atrophy

67
Q

What are three ways microglia help with homeostasis and regenerative roles?

A
  1. Promote neurogenesis
  2. Maintain synapse integrity
  3. Clear cellular debris to promote repair
    3a. synaptic pruning
68
Q

Regulatory process, reduces number of neurons and synapse, leaving more efficient synaptic configuration

A

synaptic/neuronal/axon pruning

► Med - Year 1 (48 decks)

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