NEU 490 Quiz 2 Ast Flashcards
Astrocytes Shape and Location?
Astrocytes Roles?
Local communication?
Astrocytes Abundant? Compare to neurons?
% total brain volume?
% brain glial population?
adapt size and shape to form a BLANK?
Overlap?
Star Shaped glial in the brain and spinal cord
Many roles: biochemical control of endothelial cells to help form BBB, provide nutrients to nervous tissue, maintenance to extracellular ion balance, regulation of cerebral blood flow, role in uptake of NT (glutamate), repair scarring in the brain and spinal cord flowing infections and injuries
Seen as local communication elements of the brain, can generate regulatory signals, bridge structures and create networks
most abundant macroglia (outnumber neurons 5:1)
constitute 20-50% of total brain volume
40-50% of brain glial population - 50% of glial cells are astrocytes
adapt size and shape to form a tridimensional net throughout CNS
Relatively little overlap of processes but can connect through gap junctions for intracellular Ca
Old Theory vs New Theory
Glial Fibrillary Acid Protein (GFAP)?
Old theory: homogeneous population of non- excitable cells (considered support cells but with RNA seq, ICH, and Ca imaging view has changed that they are diverse population of cells and have brain area and disease specific functions)
Homogeneous means something is uniform in nature or made up of parts that are the same or very similar, while heterogeneous means something is made up of parts that are different or unalike.
New theory: dynamic heterogeneous population of cells (don’t send AP but are excitable and send intracellular and intercellular Ca waves between diff astrocytes through long distances on response to stimulation - release glial transmitters that they make or take up)
Glial Fibrillary Acid Protein (GFAP): common astrocyte marker but the density of expression of various markers differs across astrocyte subtypes
Three Identifiable Types:
Divided according to?
Protoplasmic?
Fibrous?
Radial?
Change in shape can have reduction in number of fine processes and increase in size of soma and thickness — Divided according to morphological characteristics, location, and cellular markers
Protoplasmic: (sheet-like; gray matter) near neuronal cell bodies and synapses
Fibrous: (stellate; white matter) near myelin
Radial: (thin unbranched; white matter, progenitor cells) important for development and can tune into neurons and be guidance for neurons but different in adult brain - not considered a true astrocyte but have similar functions
Protoplasmic Astrocytes
Morphology?
Gray matter enfold?
Roles in synapses?
Role in BBB?
Take up what?
What allows for propagation of Ca?
Morphology: Highly branched and bushy processes - Stellate or Star-shaped
Gray matter(cell bodies,synapses) astrocytes that enfold cell bodies and processes - play role at synapse
Play a role in synaptic function - glutamate clearance, buffering of ion conception, modulation of functions, and regulation of blood flow in response to synaptic activities (send blood flow to active areas of the brain that’s why FMRI), formation and elimination of synapses, microglia actually phagocytes the synapses, astrocytes will tag this is a not used synapse get rid of it
Play a role in the BBB - bring blood flow
Non-overlapping domains and mutually exclusive domain - within the domain if one single astrocyte are 140,000s synapses so coordinate synaptic activity IN to blood flow
Take up glutamate bc in contact with NT
Gap junctions allow for propagation of intracellular Ca to allow for communication
One protoplasmic astrocyte can come into contact with up to BLANK synapses
140,000
Which of the following are true regarding protoplasmic astrocytes?
Gray matter
large stores of glycogen
come into contact with synapses
BBB formation
regulating blood flow
high expression of glutamate transporters
Fibrous Astrocytes
Derived from same progenitors as?
White matter?
Run between?
make contact ?
regulate?
Affect maintenance of what two things?
Frequently form?
Derived from same progenitors as protoplasmic
White matter(myelin) astrocytes - scattered in of spinal cord and brain
In the CNS matter in major routes
Run between myelinated fibers
make contact with Nodes of Ranvier
regulate environment around axons and interaction with oligodendrocytes, vascular, and microglia and regulate network activity by contact with axons - increase in Ca waves intracellular in response to APs being sent and induce release of ATP which is important for transmitter for activation of microglia and neurons and astrocytes
Affect maintenance of oligodendrocytes and effect myelin by having platelet derived growth factor alpha PDGFA which mediate survival of OPC and miotic expand of OPC
Frequently form endfeet with capillaries - BBB creation and maintenance - bring blood flow
Which of the following are true regarding fibrous astrocytes?
Located in white matter, lower expression of glutamate transporters, contact with nodes of ranvier, BBB formation, relegating blood flow, lower expression of connexions; less gap junction coupling
BLANK astrocytes release BLANK to increase oligodendrocyte progenitor cell numbers during development and influence myelination
Fibrous, (PDGFA) platelet derived growth factor alpha
Radial Glia
Biochemically and functionally distinct non?
location?
guiding what?
branched?
Progenitor cells?
Two types?
Biochemically and functionally distinct non neuronal cell class that radically spans entire width of cerebral wall from ventricular cavity(ventricles) to pial surface, ubiquitous throughout developing brain and guidance movement of neurons
Glial cells with long unbranched processes
Progenitor cells, stays in adult brain in discrete locations - act as progenitor cells for development so can turn into neurons
Müller Cells of the Retina: elongated throughout the thickness of the retina
AND
Bergmann glia: Golgi epithelial cells of the cerebellum–extend through the molecular layer to the cerebral cortex
Müller Cells of the Retina: ?
Major or minor?
Functions?
Regulate?
Optical?
Protection?
Müller Cells of the Retina: elongated throughout the thickness of the retina
Major type of glia in retina
Functions: Homeostasis and metabolic support of retinal neurons and mediate transport of ions ECF composition, trophic support, oxidative support for photoreceptors, and tights of blood retinal barrier
Regulation in synaptic activity
Optical fibers able to guide light through retina and enhance signal to noise ratio
Provide protection incase of mechanical trauma
Bergmann glia: ?
Closely associated with?
Normal?
Migrate who?
Prune?
After injury?
Bergmann glia: Golgi epithelial cells of the cerebellum–extend through the molecular layer to the cerebral cortex
Closely associated with perkingy neurons in cerebellum
Specialized astrocytes
Migration of granular cells
Synaptic pruning
Proliferative after injury called gelosis
Protoplasmic VS Fibrous Astrocytes
Protoplasmic: neurons many contacts at synapses, glutamate exposure high and glutamate clearance high with high GLT-1 expression which is the glutamate transporter that takes up glutamate, high glycogen content to convert to glucose, gap junction coupling has intense coupling connexins 43 and 30
Fibrous: neurons contact only at node, glutamate exposure low and glutamate clearance low with low GLT-1 expression, low glycogen content, gap junction coupling has less coupling mainly connexin 43
Astrocytes Functions: Neurogenesis Early Development (4) VS Adult (5)
Neurogenesis Early Development
- Scaffolding/Neuronal Migration: Directing neuron migration via direct cell contact (scaffolding), Directing neuron migration via chemo attraction and repulsion
- Neuronal Survival: Secretion of growth (survival) factors
- Synaptogenesis: Control the # of synapses formed, Maintain neuronal synapses
- Formation of the blood brain barrier (BBB)
Adult
- Energy Metabolism
- Maintenance of Neuronal Homeostasis
- Maintenance of Neuronal Activity/Plasticity
- Neuron-to-glia, Glia-to-glia and Glia-to-neuron signaling
- Regulation of Blood Flow
Scaffold - Development
Temporary structure used when building
Guides worker from bottom to top
Directing neuron migration via direct cell contact
Neurons move along processes of radial glial cells - scaffold to help new travel by Leading process does not pull the neuron along.
Lamellipodia and filopodia extend and retract.
The neuron moves by release and reformation of the adhesion beneath the cell soma
Antibodies against glial surface molecules block migration