Lecture 2 Flashcards
Composition of the Nervous System – Glia (15 cards)
What are the main classes of glial cells in the CNS and PNS?
- CNS: Astrocytes, Oligodendrocytes, Microglia, Ependymal cells
- PNS: Schwann cells, Satellite cells
What is the function of oligodendrocytes?
Myelinate axons in the CNS; one oligodendrocyte can myelinate multiple axons.
What is the function of Schwann cells?
Myelinate axons in the PNS; each Schwann cell myelinates a single axon segment.
What is the function of astrocytes?
- Provide structural support
- Maintain the blood-brain barrier (BBB)
- Regulate neurotransmitters
- Buffer ions
- Support synapse formation
What is the function of microglia?
Act as immune cells in the CNS: survey for pathogens, respond to injury, phagocytose debris, and prune synapses.
What is the function of ependymal cells?
Line brain ventricles and spinal cord; produce cerebrospinal fluid (CSF).
What is the function of satellite cells?
Surround neurons in PNS ganglia and regulate the chemical environment.
What are two main methods for visualising glial cells?
Histological staining (e.g., Nissl for neuronal soma)
Immunolabelling (e.g., GFAP for astrocytes)
How do astrocytes maintain brain structure?
Their processes interlace to provide structural integrity and support synapse organization.
What is a tripartite synapse?
A synapse involving a presynaptic neuron, postsynaptic neuron, and an astrocyte.
How do astrocytes support neuronal transmission?
- Buffer extracellular K+
- Clear neurotransmitters (e.g., glutamate, GABA)
- Supply glutamine for neurotransmitter synthesis
- Provide lactate as an energy source
What is the role of myelin-producing cells in neuronal transmission?
Increases the speed of action potential conduction by insulating axons.
How do astrocytes contribute to the blood-brain barrier (BBB)?
They induce tight junctions in endothelial cells and support BBB integrity.
How do astrocytes respond to CNS injury?
Form glial scars to protect surrounding tissue and stabilize the injury site.
How do microglia respond to injury?
Migrate to the injury site, phagocytose debris, and modulate inflammation.
