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33 Cards in this Set

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  • Back
where are electrical synapses found?
retina and pacemaking functions (myocardium)
what is a connexon?
a connexon is a gap junction made up of 4 connexins
do glia have connexons/electrical synapses b/t eachother
yes, why else would i ask?
what invades an ischemic area in a stroke?
glia (they dont need O2)
what are the 2 types of glia?
macroglia - everything else
microglia - macrophages
embryological origin of microglia?
mesoderm (they are macrophages)
2 types of astrocytes, structure, location and function
type 1 - short and stubby - in grey matter

type 2 - long processes - in white matter - form end feet on blood vessels
what is principally responsible for enforcing the blood brain barrier?
the astrocytic end feet?
where are radial glial cells cell bodies located?
near the ventricles
why is heroin more potent than morphine?
heroin is more lipophilic and can therefore cross the BBB more easily
what are 3 of the substances that form the BBB?
occludin
claudin
cadherins
what do astrocytes release that cause the formation of new blood vessels in response to ischemia?
vacular endothelial growth factor (VEGF)
what substance do type 2 astrocytes release that induces the blood vessels to form tight junctions?
angiopoietin-I
what must be given along w/ L-Dopa to allow it to cross the BBB?
MAO inhibitors
what substances are actively transported across the endothelial cell in the brain?
glucose
amino acids
vitamins
why can glial tumors be given chemotherapeutic agents w/o worrying about the BBB?
they dont have a BBB
why can the loss of one oligodendrocyte in the CNS cause so much damage?
an oligodendrocyte may myelinate 50 different axons.
what molecule makes the initial contact b/t the oligodendrocyte processes and the axon in the CNS?
MCAM
what molecule anchors adjacent layers of myelin in the CNS?
PLP - phospolipid proteins
what molecule anchors adjacent layers of myelin in the PNS?
P0 - protein zero
what molecule serves as a spacer b/t adjacent layers of myelin in the CNS and PNS?
myelin basic protein - MBP
what is the signal conduction velocity in a myelinated axon?
200 m/s
what determines if an axon will be myelinated in the PNS?
the size of the axon
greater than 1/3 micrometer and it will be myelinated
how does a progenitor cell produce either an oligodendrocyte or an astrocyte?
the progenitor cell will divide exactly 8 times in the presence of PDGF (platelet derived growth factor)

it has a set number of PDGF receptors and after 8 divisions, it can no longer respond

in the presence of CNTF (cellular neurotrophic factor), the daughter cells will become astrocytes. by default, they become oligodendrocytes
what forms a scar in the CNS when an axon is damaged?
astrocytes
what molecules do oligodendrocytes produce that are paralyzing neurites?
NOGO
and
neurite outgrowth factor
when do schwann cells release Ach?
when a muscle is denervated, schwann cells will release Ach to stimulate it so it does not atrophy
where does the different regenerative abilities of the CNS and PNS come from?
differences in the glia?
where are ERB-2 and ERB-4 receptors expressed?
on radial glial cells
what happens to radial glial cells after they stop interacting with neurons
they collapse, retract their processes, and become astrocytes or interneurons
how do astrocytes control the potassium concentration in the extracellular space in the brain?
they take up K (from lots of AP) with their end feet on nodes of ranvier and dump K into the blood vessels via their end-feet on vessels
how do astrocytes and neurons eat off the same plate?
astrocytes take up glucose from epithelial cells and turn it into lactate taking 2 ATP's from the 36. they then deliver lactate to the neuron's far reaching axons, etc.
when the brain swells, which cells are swelling?
the glia. the neurons dont swell that much.