Glia; form and function

Question 1

What are glia?

Answer 1

non-excitable, axon myelinating cells

Question 2

How do you identify glial cells?

Answer 2

-not seen by electrophysiological techniques
can be identified through:
-morphology
-expression specific markers
-immunohistochemical identification

Question 3

What does the brain contain?

Answer 3

neurones and glia

Question 4

what are the types of macroglia?

Answer 4

• schwann cells
• oligodendrocytes
• ependymal cells
• astrocytes

Question 5

What are the myelin forming cells

Answer 5

• schwann cells (periphery)

- oligodendocytes

Question 6

Apart from their locations, what is the difference between Schwann cells and oligodendrocytes?

Answer 6

Oligodendrocytes can myelinated multiple axons

Question 7

Can regeneration occur in the PNS?

Answer 7

• yes

- schwann cells and endoneurial tube surround the axon encourage growth

Question 8

Can regeneration occur in the CNS?

Answer 8

• no
• no endoneurial tube
• actively prevented by signalling in CNS (prevent wonky connections being made)

Question 9

What is the role of ependymal cells?

Answer 9

• form the walls of the ventricles in the brain and the central canal of the spinal cord
• involved in the production of cerebrospinal fluid
• ciliated so help circulate CSF

Question 10

What is the largest and most numerous glial cell type?

Answer 10

astrocytes

Question 11

What is the structure of astrocytes?

Answer 11

• stellate morphology
• processes can be long
• can look like dendrites

Question 12

What is a marker for astrocytes?

Answer 12

GFAP

Question 13

What is the role of astrocytes?

Answer 13

• neuronal guidance during development
• form the architecture of the brain and spinal cord
• astroglia stem cells (can differentiate into nerve cell or a glial cell)

Question 14

What is the difference between transporters and channels?

Answer 14

Transporters are active, channels are passive

Question 15

What are the roles that astrocytes carry out?

Answer 15

• Homeostatic mechanisms
• K+ buffering in the ECF
• express transporters to take up K+ ions
• prevents accumulation of K+ resulting from neurone firing
• controlling the synapse
• express neurotransmitter transporters
• prevent diffusion outside of synapse
• protecting the synapse
• express various transporters
• prevent entry from outside synapse
• protect synapse fro ECF
• maintain synaptic microenvironment
• neurovascular coupling
• responding to insult

Question 16

How are astrocytes involved in neurovascular coupling?

Answer 16

• provide energy to neurone
• important for highly active neurones
• astrocyte may modulate cerebral mood flow
• indirect measure of neuronal activity measured

Question 17

How do astrocytes respond to insult?

Answer 17

• damaged cells release ATP and glutamate this causes astrocyte hypertrophy and proliferation which is called reactive astrogliosis
• from glial scars around the injured CNS and produce inhibitory molecules that inhibit growth of damaged or severed axons

Question 18

What are the resident immune competent cells in the CNS?

Answer 18

microglia

Question 19

Where do microglia arise from?

Answer 19

bone marrow monocytes

Question 20

Where do microglia migrate to during development?

Answer 20

nervous sytem

Question 21

How do microglia respond to danger?

Answer 21

• motile processes monitor the environment
• danger signals (disease) or injury trigger transformation
• in the activated state genes get turned on to deal with injury defence/repair
• they can also differentiate into phagocytes