Histology and Cells of CNS Flashcards
name the three functional classes of neurons
sensory
motor
interneuron
what is the rough ER called in neurons?
Nisl Substance
where is there not much rough ER?
near the axon hillock…will appear lighter on slide
name the five neuroglia cells
astrocytes schwann cells ependymal cells oligodendrocytes microglia
what cell contributes to the BBB?
astrocyte foot processes
what are the 5 functions of astrocytes
scavenge debris supply energy for metabolism contribute to the glie limitans structural support help form scar tissue
what cell covers the nodes of ranvier in the CNS?
astrocytes
what is the glia limitans?
barrier between pia mater and nervous tissue
what is the role of the oligodendrocytes in the CNS?
make myelin for several neurons each
what is the role of the microglia?
small phagocytic cells derived from monocytes, can become APCs when activated and secrete cytokines
what is the function of schwann cells?
in PNS they wrap neurons with myelin…can only do one per schwann cell though`
can a schwann cell support PNS neurons even if it isnt wrapping with myelin?
yes…but just isnt wrapped in myelin but surrounds many cells
what is the role of the ependymal cells?
secrete CSF in the ventricles and line the ventricles of the brain
what neurons are usually unmyelinated?
postganglionic neurons in the ANS
name the three layers surrounding a nerve
epineurium
perineurium
endoneurium
what does the epineurium cover?
the whole nerve
what does the perineurium cover?
bundle of nerve fibers within the nerve
what is a ganglia?
encapsulate aggregation of neuronal cell bodies outside of the CNS
what are the two types of ganglia?
autonomic and sensory
what surrounds cells in the autonomic ganglia?
satellite cells
are cell bodies in autonomic ganglia normal or irregular shape?
irregular shape
are cell bodies in sensory ganglia normal or irregular shape?
normal round shape
are cells in autonomic close together or spread out?
spread out
are cells in sensory ganglia close together or spread out?
close
what type of neuron is in sensory ganglia?
pseudounipolar
name the six layers of the cerebral cortex from out to in
molecular external granular external pyramidal internal granular internal pyramidal multiform layer
what type of cell is in the pyramidal layers?
pyramidal shaped cell bodied neurons
name the three parts of the BBB
endothelial cells
foot processes from astrocytes and
thick basement membrane
do oligodendrocytes or schwann cells have a basal lamina?
schwann cells
what is the role of satellite cells?
provide support and modulate neuronal enviro in the PNS
what are the two directions for axonal movement?
anterograde and retrograde
anterograde movement on axon happens at what two speeds?
slow…1mm/day and fast…400mm.day
retrograde movement happens at what speed?
intermediate…100-200mm/day
retrograde transport moves in what direction?
from axon terminal to cell body
anterograde trsnport moves in what direction?
cell body to axon terminal
dynein assists in retrograde or anterograde?
retrograde
kinesis assists in retrograde or anterograde?
anterograde
what is axotomy?
cut an axon
what happens to the axon of neuron after axotomy?
anterograde degen and retrograde degen right at cut
what happens to cell body of neuron after axotomy? 3 things
nucleus moves to periphery
nissl substance decreases in amount
cell swells
explain why crush injuries lead to accurate nerve reinnervation
axons distal to site of crush still have basal lamina tract that was layed down by the schwann cells
what happens to axon growth following crush injury?
proximal stump grows into distal stump and follows basal lamina tract
explain why transection of a nerve leads to less accurate reinnervation
basal lamina put down by the schwann cells gets cut too and so the proximal stumps can go into different distal stumps and innervate in a different spot than they are supposed to
what is it called when you have reinnervation following a nerve transection but it is a bit off?
anomalous reinnervation
what happens when regeneration of axon occurs but it cannot find the distal stump basal lamina?
leads to axonal cluster…called a neuroma…and there is no reinnervation so degenerates
can remyelination occur in CNS or PNS or both?
really just schwann cells in PNS able to do it
can regeneration occur in the CNS?
not as likely as in PNS because there is not a basal lamina like put down by the schwann cells in the PNS
what is molecular plasticity?
axon membranes acquire new voltage Na channels after injury
what is synaptic plasticity?
increased activity at synapse
what is collateral sprouting of axons?
targets that lose innervation can get sprouts of axons from surrounding axons
