Glia Flashcards
What is the function of glial cells?
- Axon myelinating cells
- Cerebrospinal fluid production
- Astrocytes, Neurotransmission and neuron cell function
- Microglia, resident CNS immune competent cells
- Glial cells response to CNS injury
What are glial cells?
Non-excitable cells
How are glial cells identified?
- Morphology
- Expression specific markers (cell surface or intracellular)
- Immunohistochemical identification
- Not seen by electrophysiological techniques
What are the types of glial cells?
Micro and macroglia
What are the different types of macroglia?
- Schwann cells (periphary)
- Oligodendrocytes (CNS)
- Ependymal cells
- Astrocytes
What are the functions of schwann cells?
- Myelin-forming
- One cell myelinates one axon
- PNS
- Make axon regeneration possible
- Schwann cells surrounding axons encourage growth
What are the functions of oligodendrocytes?
- Myelin forming
- One cell can myelinate multiple axons
What are the functions of ependymal cells?
- Form the walls of the ventricles in the brain and the central canal of the spinal cord
- Involved in the production of cerebrospinal fluid (CSF)
- Ciliated cells
- Help circulate the CSF
What are the functions of astrocytes?
- Nuronal guidance during development
- Form the architecture of the brain and spinal cord
- Astroglia stem cells: Adult neurogenesis and gliogenesis
- Astrocytic processes envelop the synapse
- K+ buffering in ECF
- Express neurotransmitter transporters
- Express various transporters
- Neurovascular coupling
- Form glial scars around injured CNS
- Produce inhibitory molecules that inhibit growth of damaged or severed axons
How is axon regeneration prevented in the CNS?
- No endoneurial tube
- No regeneration
- Regeneration is actively prevented by signalling in CNS
How are astrocytes involved in K+ buffering in ECF?
- express transporters to take up K+ ions
- Prevents accumulation of K+ resulting from neuron firing
How are astrocytes involved in expressing neurotransmitter transporters?
Prevent diffusion outside of synapse
How are astrocytes involved in expressing various transporters
- Prevent entry from outside synapse
- Protect synapse from ECF
- Synaptic microenvironment
How are astrocytes involved in neurovascular coupling?
- Envelop capillaries and neurons
- Provide energy to neuron
- Important for highly active neurons
- Take up glucose from blood
- Convert to lactate and export it to the neuron
- May modulate cerebral blood flow
- Indirect measure of neuronal activity
- fMRI
- Blood-oxygen-level dependant
How are astrocytes involved in injury?
- Damaged cells release ATP and glutamate
- Astrocyte hypertrophy (increase in size) and proliferation = reactive astrogliosis
- Increase GFAP expression
- Form glial scars around injured CNS
- Produce inhibitory molecules that inhibit growth of damaged or severed axons
