Glial cells

Question 1

What are the different types of glial cells?

Answer 1

Atrocytes
Oligodendrocytes in CNS (and Schwanna cells in PNS)
Micgroglia
Ependymal cells

Question 2

What is the function of astrocytes?

Answer 2

• most abundant glial cell.
  Important for :
  -breakdown of neurotransmitters
• growth factors (chemicals involved in growth and repair of damaged cells).
• structural support (anchor neurons to help get a regular blood supply).
• transport nutrients into neuron and remove waste products
• protects BBB (helps to push endothelial cells together)

Question 3

What is the function of oligodendrocytes?

Answer 3

• provides myelin sheath (insulation of neurons) –> only in brain.
• in peripheral NS Schwann cells provide myelin sheath
• in MS –> immune system attacks oligodendrocytes

Question 4

What is the function of microglia?

Answer 4

• main immune defence in the brain
• when there is an injury or infection, microglia multiply and migrate to the site –> engulfs microorganism or infected neurons.

Question 5

What is the function of ependymal cells?

Answer 5

• line the ventricles and central canal of the spine

Question 6

How do neurons and glial cells differ?

Answer 6

• glial cells do not cause APs (rapid electrical signals) like neurons
• glia surround and ensheath neuronal cell bodies, axons and synapses throughout nervous system.
• neurons communicate via synapses

Question 7

How do astrocytes communicate with each other?

Answer 7

• communicate via waves of calcium ions, propagating information over large distances.
• stimulation of one astrocyte can cause a calcium response in neighbouring astrocytes (indicating a distinct network of astrocytes in a mosaic pattern).
• these cells are linked by structures in their cell bodies called gap junctions.

Question 8

How do glia and neurons communicate?

Answer 8

• can make contact with, and ensheath thousands of synapses formed between neurons
• synapses have an astrocytic projection that envelops the synapse.
  Tripartite synapse:
• astrocytes respond to many of same NT as neurons. When a neuron releases Ca- based signalling, this cascade in astrocytes and also release various active substances such as LTP.
• the synaptic localisation of astrocytes means they are ideally placed to respond to and monitor synaptic activity.
• astrocytes can release proteins, which control synapse formation, regulate presynaptic function and modulate response of postsynaptic neuron and NT.

Question 9

How do we know that abnormal glia activity is linked to neurodegenerative diseases?

Answer 9

• most neurodegenerative disorders are associated with abnormal glial activity
• can have excitotoxic effects (e.g. too much glutamate in the synapse)
  Evidence:
• increase glial activity in Parkinson’s Disease and schizophrenia
• increased cytokines in neurodegenerative disorders
• studies that show rats who get an infn early in life have a hyperactive immune response (hyperactive glial activity and cytokines)–> affects memory (indicating possible brain damage)