Glial Cells - Neuroglia

What is a glial cell?

• Cell which support and maintain the environment of neurones.

• Involved in processes like providing nutrients, removing waste and forming myelin.

• Primary types are astrocytes, oligodendrocytes, microglia.

What is grey matter?

• Consist of neuronal cell bodies, dendrites and synapses. Involved in processing, cognition and primarily located in the outer layer of the brain (cortex)

What is white matter?

• Composed primarily of myelinated axons

• Responsible for transmitting electrical signals across different brain regions.

• Myelin gives pale appearance to white matter

What is an astrocyte and what does it do?

Function

• Provides structural and metabolic support for neurons.

• Regulates blood-brain barrier and maintains extracellular environment (ion balance and neurotransmitter regulation).

• Supports development of nerve cell and participates in synapse function + neuroplasticity.

Role in the brain

• facilitates comms between neurons + contribute to remodelling + repair of neural networks.

• Also involved in neurotransmitter uptake and recycling - e.g. glutamate + GABA.

• Regulates vessel constriction + dilation (can sense metabolic rate of adjacent nerve cells)

What are oligodendrocytes and what do they do? What does it look like?

Function

• produce myelin in the CNS - this insulates axons and speeds up electrical signal transmission via saltatory conduction.

• Each oligodendrocyte myelinates multiple axons, making up to 50 myelin sheaths

• Oligodendrocyte body does not attach to the axon

• Found in higher numbers on white matter

Appearance

• round + dense nucleus

• small cytoplasm with multiple orcesses

What is the difference between myelination in the PNS and the CNS?

in the CNS:

• each oligodendrocyte extends multiple processes - helps to support up to 50 diff processes, can be distant or on the same axon

• cell body + nucleus remain distant from the sheath it forms

• Support is maintained by astrocytes - gives stable chem environment

in the PNS:

• Schwann cell creates 1 myelin sheath

• This attached cell body + nucleus directly to the axolemma - so no extended processes

• Connective tissue and basal lamina gives support for myelin sheaths.