023 + 024 Glia Flashcards
what type of cell make up the majority of the brain?
glial cells
what is the difference between neurons and glial cells?
- neurons can conduct action potentials
- glial cells cannot conduct action potentials
what are the names of main types glial cells in the CNS(5)?
- astrocytes
- oligodendrocytes
- microglia
- ependymal cells
- NG2 cells
what are the names of main glial cells in the PNS(4)?
- myelinating Schwann cells
- non-myelinating Schwann cells
- satellite cells
- enteric glia
what were glial cells described as when they were first discovered?
’ glue ‘ of the CNS
what is the most common glial cells in the brain?
astrocytes
what is the function of astrocytes (5)?
- developmental role in migration of neurons and axon guidance
- homeostasis of neuronal microenvironment: ionic, metabolic, neurotransmitter uptake
- Blood-brain barrier induction and maintenance
- nutrition of growth factors
- synaptogenesis and synapse remodeling
describe the structure of astrocytes
= star shaped highlt ramified glial cells
- attach to neuron body and axon and connect to ependymal cells to link to vasculature
- interact with synpases, nodes of Ranvier, blood vessels…
give some examples of astrocyte subtypes
- protoplasmic astrocytes
- fibrous astrocytes
- radial glial cells
- Bergmann glia
- Muller glia
what is the structure and function of protoplasmic astrocytes?
- biggest astrocyte population in grey matter
-mainly found in hippocampus and cerebral cortex - very highly ramified (can touch multiple synapses in 1 area)
- involved in neuromodulatory role
what is the structure and function of fibrous astrocytes?
- organized along white matter tracts
- less ramified and smaller
- can contact nodes of Ranvier
- maintain homeostasis in their region
what is the structure and function of radial glia cells?
- long thin cells stretching from apical to basal
- used in neuronal migration during cerebral cortex development
- known as the main neuronal/glial progenitor present during brain development
what is the structure and function of Bergmann glia?
- specific astrocytes for cerebellum
- ensheaths and controls cerebellar synapses
- also involved in granular cell migration
what is the structure and function of Muller glia?
- astrocyte type specific for retina
- involved in cell migration, neuronal generation and control of synapses of the retina
describe the function of astrocytes and the neurovascular unit
- astrocytes have connections called ‘end feet’ which signal to blood vessels to expand or narrow the blood vessels to control flow of oxygen and nutrients
- astrocytes can release gliotransmitters (like glutamate) to send signals to neighboring neurons
- so this allows a sense of synaptic activity to control delivery of oxygen and nutrients