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

What are Schwann Cells?

Answer 7

Myelinating cells in the PNS

Question 8

What are oligodendrocytes?

Answer 8

Myelinating cells in the CNS

Question 9

Can regeneration occur in the PNS?

Answer 9

• yes

- schwann cells and endoneurial tube surround the axon encourage growth

Question 10

Can regeneration occur in the CNS?

Answer 10

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

Question 11

What is the role of ependymal cells?

Answer 11

• 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 12

What is the largest and most numerous glial cell type?

Answer 12

astrocytes

Question 13

What is the structure of astrocytes?

Answer 13

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

Question 14

What is a marker for astrocytes?

Answer 14

GFAP

Question 15

What is the role of astrocytes?

Answer 15

• 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 16

What are the homeostatic mechanisms that astrocytes carry out?

Answer 16

• Homeostatic mechanisms:
• controlling the synapse
• neurovascular coupling
• responding to insult

Question 17

How are astrocytes involved in neurovascular coupling?

Answer 17

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

Question 18

How do astrocytes respond to insult?

Answer 18

• 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 19

What are the resident immune competent cells in the CNS?

Answer 19

microglia

Question 20

Where do microglia arise from?

Answer 20

Bone marrow monocytes

Question 21

Where do microglia migrate to during development?

Answer 21

nervous sytem

Question 22

How do microglia respond to danger?

Answer 22

• 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

Question 23

How do astrocytes prevent K ion build up from high frequency neurone firing?

Answer 23

Expresses K transporters to take up K ions and buffer then within the ECF

Question 24

What is the role of the astrocytes in controlling the synapse?

Answer 24

• express neurotransmitter transporters

* prevent diffusion of the neurotransmitter outside of synapse

Question 25

what is the role of the astrocytes in protecting the synapse?

Answer 25

• express various transporters
• prevent entry from outside synapse
• protect synapse fro ECF
• maintain synaptic microenvironment