Glia Flashcards
What are 3 unique features about glia (as opposed to neurons)?
- No axons
- Can divide
- Inexcitable
What make up the majority of cells in the brain?
Glia
What are the 2 main classifications of Glia?
Macroglia and Microglia
What are the 4 main types of Macroglia?
- Astrocytes
- Oligodendrocytes
- Schwann Cells
- Oligodendrocyte Progenitor Cells
Astrocytes are processes that cover _____ and surround _____
neurons; synapses
The end feet of astrocytes terminate on _____ (pial surface) and extend all the way to the ends of _____
blood vessels; synapses
Oligodendrocytes are the the ____ as Schwann Cells are to the _____
central nervous system; peripheral nervous system
What forms CNS myelin?
Oligodendrocytes
What forms PNS myelin?
Schwann Cells
Microglia are derived from blood _____, which are macrophages of the brain.
monocytes
What is the origin of microglia?
the mesoderm
What is the main glial function of astrocytes?
Uptake of Neurotransmitters
Describe the glutamate uptake of astrocytes. What is the purpose of this uptake?
- Glutamate: high affinity Na+ - dependent uptake
- GlutaMINE synthetase (glutaMATE+NH4 –> glutaMINE)
- Recycled to neurons (glutaMATE-glutaMINE cycle)
Purpose: to prevent excitotoxicity
Describe the GABA uptake of astrocytes
- High affinity NA+ - dependent uptake
- GABA transaminase
- GABA –> Krebs Cycle –> GlutaMATE –> GlutaMINE
Radial glia are stem cells for neuronal ______ cells
progenitor
Guidance of neuronal migration is when neurons move along what?
radial glial cell processes
Glial ______ factors influence neuronal development
neurotrophic
GDNF stands for what?
Glial cell line-derived neurotrophic factor
What does GDNF do?
provides trophic support for dopamine neurons
Astrocytes release what to promote synapse formation?
thombospondins
Microglia prune excess what (even in the adult brain)? When does this occur?
synapses; during sleep
Astrocyte end-feet surround blood vessels. Developing vessels grow along what?
glial processes
Astrocytes release what growth factor?
VEGF: Vascular endothelial growth factor
What type of junction is formed in the blood brain barrier?
tight junctions
Astrocytes play a role in regulating ________ and help to regulate it in the brain by producing what kind of factors?
blood flow; vasoconstricting/vasodilating
Microglia are resident ____ of the brain and are considered the interface between which body system and the brain?
macrophages; immune
What are the intrinsic antigen presenting cells of the brain?
microglia
What cells are constantly surveying the brain for injury?
microglia
What cells differentiate into amoeboid-like cells to scavenge debris at the site of injury?
microglia
What cells prune unneeded synapses during development?
microglia
What is Reactive Gliosis?
the response of glial cells to brain injury or pathology
Astrocytes have 3 main actions. What are they?
- Proliferation/differentiation
- Express GFAP (glial fibrillary acidic protein)
- Form glial scars
Which cells form glial scars?
Astrocytes
Which cells express GFAP?
Astrocytes
Which cells are known for proliferations/differentiations?
Astrocytes
Microglia are known to differentiate into _____-like cells to scavenge for ____ at the site of injury
amoeboid; injury
What cells mediate the immune response of the brain?
Microglia
What cells promote regeneration of nerves in the PNS?
Schwann Cells
What cells act as conduits for regenerating axons?
Schwann Cells
T/F: Severed peripheral nerves CAN regenerate.
true
What cells prevent regeneration of nerves in the CNS?
Oligodendrocytes
What kind of proteins, such as Nogo, inhibit axon growth?
oligodendrocyte
T/F: Regeneration CAN be partially restored in the CNS. Why or why not?
true, because there are 3 ways to do so:
- Transplants of olfactory ensheathing cells (glia)
- GDNF (glial cell line-derived neurotrophic factor)
- Antibodies against oligodendrocyte proteins
Why are SCI so devastating?
Because the CNS has a hard time regenerating nerves since oligodendrocytes PREVENT this
Chronic pain can result from damage to what system?
PNS
What cells play a role in chronic pain?
microglia
What becomes activated in the dorsal (sensory) horn of the spinal cord following peripheral nerve damage?
microglia
What do microglia release?
Diffusible factors, such as BDNF which is brain-derived neurotrophic factor
What does the release of diffusible factors via microglia do? What is the clinical application of this?
- Increases neuronal excitability –>
- Increases pain –>
- Chronic pain
Result: Nerve blocks/corticosteroid injections to reduce pain needed
In Alzheimer’s disease, many mutations are expressed in the _____ rather than the neurons
microglia
Microglia surround ____ and phagocytize _____
amyloid plaques; b-amyloid
If microglia are mutated (damaged/altered), they cannot remove _____, which is linked to developing Alzheimer’s
wastes/plaques
In MS, autoimmune system attacks what kinds of cells?
oligodendrocytes
In MS, the body believes myelin basic protein (and others) are _____ and attack the oligodendrocytes, which causes ________.
antigens; demyelination
In Autism-spectrum disorders, the ____ are considered dysfunctional due to altered _____ and numbers.
microglia; morphology
Microglial-specific mutations are commonly associated with what disorder?
Autism
In Epilepsy, epileptogenesis can occur in regions of reactive _____ and ____ scars.
astrocytes; glial
Abnormal glial cells may contribute to epileptogenesis due to the reduced uptake of which neurotransmitter?
glutaMATE
Brain tumors are in less than 2% of all malignancies, but are largely untreatable. They are most commonly derived from ______, ______ and ______ cells which are glia lining the ventricles.
astrocytes; oligodendrocytes; ependymal
Gliomas release what neurotransmitter which kills neurons and makes room for a tumor to grow in the brain?
glutaMATE
The key factor in brain disease is what?
glutaMATE
What are the main types of glial cells?
- Astrocytes
- Oligodendrocytes (CNS)
- Schwann Cells (PNS)
- Microglia
Reactive gliosis mainly affects ____ and _____
astrocytes; microglia
Glia can aid in regeneration in the ____ and hinder regeneration in the ____
PNS; CNS
Glial cells are implicated in many ______ diseases
neurodegenerative