Glia - form and function Flashcards

1
Q

How many more glia are there than neurones in a human brain?

A

10x more glia

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2
Q

What do glia offer?

A

Physical support
Metabolic support
Electrical insulation
Guiding connections

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3
Q

How are glia noticeable?

A

They cannot be seen by electrophysiological techniques
Morphology
Expression specific markers
Immunohistochemical identification

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4
Q

What are the two divisions of glia?

A

Macroglia

Microglia

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5
Q

Name the 4 types of macroglia

A

Schwann cells
Oligodendrocytes
Ependymal cells
Astrocytes

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6
Q

Which two cells form myelin?

A

Schwann cells

Oligodendrocytes

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7
Q

What are the differences between Schwann cells and oligodendrocytes?

A

Schwann cells are in the peripheral nervous system
Oligodendrocytes are in the central nervous system
Schwann cells myelinate one axon
Oligodendrocytes myelinate many axons (up to 30)

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8
Q

What does myelination promote?

A

Regeneration

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9
Q

Can axen regeneration occur in the PNS or CNS?

A
PNS = yes
CNS = no
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10
Q

What allows axon regeneration in the PNS?

A

Schwann cells and endoneurial tube surrounding the axon encourage growth

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11
Q

What stops axon regeneration in the CNS?

A

No endoneurial tube

Prevented by signalling in CNS

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12
Q

What is the role of an ependymal cell?

A

Form the walls of the ventricles in the brain and central canal of the spinal cord
Produce cerebrospinal fluid

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13
Q

What structural adaptations do ependymal cells have?

A

They are ciliated

Helps circulate the cerebrospinal fluid

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14
Q

Describe an astrocyte

A

Largest glial cell

Most numerous glial cell

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15
Q

What is the function of an astrocyte?

A

Neuronal guidance during development

Form architecture of brain and spinal cord

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16
Q

What are astroglia stem cells responsible for?

A

Adult neurogenesis

Gliogenesis

17
Q

What role do astrocytes play in homeostasis?

A

K+ buffering in extracellular fluid

18
Q

How do astrocytes buffer K+

A

They have express transporters to take up K+ ions

19
Q

Why do astrocytes buffer K+

A

Prevent accumulation of K+ as a result of neuron firing

20
Q

How do astrocytes work alongside synapses?

A

They express neurotransmitter transporters

Prevent diffusion outside of the synapse

21
Q

How do the astrocytes protect the synapse?

A

They express various transporters
Prevent entry from outside of the synapse
Protect synapse from extracellular fluid

22
Q

What do astrocytes create at the synaptic junction?

A

A synaptic microenvironment

23
Q

Explain neurovascular coupling

A

The ‘foot’ of the astrocyte envelops the capillaries and neurons
Provides energy to the neurons
Essential in highly active neurons

24
Q

What can the astrocyte modulate?

A

Cerebral blood flow

25
Q

What is cerebral blood flow and indirect measure of?

A

Neuronal activity

26
Q

What does a damaged astrocyte release?

A

ATP and glutamate

27
Q

How does the astrocyte cell respond to damage?

A

Hypertrophy

Proliferation

28
Q

What is the name given to the proliferation of astrocytes in response to damage?

A

Reactive astrogliosis

29
Q

What do astrocytes form in the CNS when damaged?

A

Glial scars

30
Q

What does an astrocyte produce when an axon is damaged?

A

Inhibitory molecules to prevent growth

31
Q

Describe a microglia

A

Smallest glial cell

10% of glial cells

32
Q

What is the role of microglia?

A

Immune cell of the CNS

33
Q

Where do microglia originate from?

A

Bone marrow monocytes

34
Q

When do microglia migrate to the nervous system?

A

During development

35
Q

How does a microglia work?

A

Motile processes monitor environment

Signals of disease or injury trigger transformation into phagocytic cell

36
Q

What is reactive microgliosis?

A

The activation of microglia into phagocytic cells

37
Q

CNS immune system and injury repair is carried out by which glial cell?

A

Microglia