2- neurons glia Flashcards
for each of following choose gray or white matter
a) nucleus
b) lemniscus
c) ganglion
d) peduncle
e) cortex
f) funiculus
g) body
h) fasciculus
i) tract
a) nucleus = gray
b) lemniscus = white
c) ganglion = gray
d) peduncle = white
e) cortex = gray
f) funiculus = white
g) body = gray
h) fasciculus = white
i) tract = white
Astrocytes
What is their function structurally?
interdigitate with neurons and help fill volume of brain
Astrocytes
What is their biochemical function
keep neurons isolated by retrieving neurotransmitter that leaks out of synapse and then recycle back
Astrocytes
How does it help maintain ionic equilibrium
soak up K+ that flows out of cells when neurons fire action potential
Astrocytes
How is it involved in blood flow regulation
envelops blood vessels in BBB and helps endothelial cell maintain contacts
communicate with endothelial cells to maintain specialized contacts to prevent from freely enter the extracellular space
Astrocytes
Function after damage to CNS?
glial scar formation
Microglia
Where are located
extend btwn neurons in white and gray matter like astrocytes but NO OVERLAP
Microglia
major function
macrophages for surveillance until activated by stimuli and clear debris from brain
Oligodendrocyte
Major function
How many axons
myelin production in CNS
multiple axons
Oligodendrocyte
what happens when CNS is damaged
inhibit axonal regeneration by phagocytzing the myelin shath
Schwann cell
major function
how many axons
myelin production in PNS
one axon
Schwann cells
what happens when PNS neuron is damaged
celar debris then line up along endoneurium to give regenerating axons path to grow
Dendrite
Major function
How many can there be for each neuron
conduct electrical signal (NOT ACTION POTENTIAL) and integrate signals
many dendrites/neuron
Axon
Contains?
Axons > 1 um in diameter usually ____
contains VG ion channels to generate action potential
> 1 um usu myelinated
Nissl substance
what is it?
indicates what in neurons
dark staining RER and ribosomes in cell bodies and dendrites
= RNA stain
indicates high metab activity
Blood flow in brain regulated by ___
autoregulation of arterioles in the brain
Incr in blood pressure in brain causes ____ to maintain diameter
in functional hyperemia, local incr in neuronal activity causes ____ and thus ___
basis for __ and __
incr in vascular tone
incr metabolic demand and thus incr local blood flow
fMRI and PET
PET vs. fMRI function
PET = inject tracer in blood
fMRI = blood flow from Hgb properties
What is BBB made of?
What is required for substance to enter CNS
made of endothelial cells forming tight junctions so NO FENESTRATIONS
must be actively transported or diffuse through endothelial cell
How does astrocytes respond to glutamate
1) absorb glutamate
2) release arachidonic acid
3) enzymatic rxn by P450 to EET
4) EET acts on arterioles to hyperpolarize cell membrane
5) prevents smooth muscle constriction and decr vascular tone
6) vessel dilation, incr blood flow to brain areas releasing glutamate
PNS nerve damage is mainly repaired by ___ using what cell type?
regeneration of damaged axons by Schwann cells
Mechanism of Schwann cell regenerating damaged PNS axon
1) Schwann line up along endoneurium and secrete growth promoting substance
2) provides path towards synapse
How does peripheral nerve damage lead to sensory loss in CNS
1) central terminals of damaged cell emit signals that activate microglia
2) microglia remove synapses and cause reorg of brain areas
3) causes neuropathic pain
How does CNS repair neuron damage
clear out neuron; only some areas can regrow
