Neurohistology and Nervous System repair Flashcards
Where is the subarachnoid space
between the pia and the arachnoid mater
what is a perikaryon
neuron cell body
what is a multipolar neuron
cell body at one end
what is bipolar neuron
cell body in the middle
what is a pseudopolar neuron
cell body in the middle, on a stalk
what is found in grey matter
cell bodies
what is found in white matter
axons
what is the axon hillock
where the cell body meets the axon
what does nissl substance stain
ER and polyribosomes
what is the neocortex
cerebral cortex
how many layers of the cerebral cortex are there
6
how many layers of the cerebellar cortex are there
3
grey superficially and white is deep
what are the layers of the cerebellar cortex
molecular
purkinje cells
granular
what is found in the granular layer
granular cells and golgi cells
what is found in the molecular layer
basket cells, stellate cells and fibres
describe purkinje cells
multipolar neurons
largest cells in the cerebellum
pear shaped
dendritic tree which expands outwards into the molecular layer
receive afferent information from the CNS
Where are astrocytes, oligodendroglia, ependymal cells and microglia found
the CNS
where are schwaan cells and satelite cells found
PNS
what do oligodendroglia and schwaan cells do
form myelin sheaths
what do astrocytes do
structural and metabolic support for neurons
where are fibrous astrocytes found
white matter of the CNS
Where are protoplasmic astrocytes found
grey matter of the CNS
where are muller glia found (astrocytes)
retina
where are radial glia (astrocytes) found
developing CNS
What forms the BBB
endothelial cells, tight junctions and astrocyte end feet
what is the maximum weight allowed through the BBB
500 daltons
what is the function of ciliated cuboidal ependymal cells
line the ventricle, secrete and reabsorb CSF
where is CSF produced
chroroid plexus
what is the function of microglia
immune function like macrophages, able to phagocytose cell debris upon injury
release cytokines
what are the functions of oligodendrocytes
one cell is able to myelinate several axons
what cells is affected in MS and leukodystrophy
oligodendrocytes
how many schwaan cells can myelinate one axon
1 cell per axon
what is the function of myelin
Insulation and increased velocity via saltatory conduction
what axons are unmyelinated
fibres carrying pain, temperature and itch
describe unmyelinated axons in the PNS
enveloped by schwaan cells
this does not happen in the CNS
what are ganglia
aggregations of nerve cells outside the CNS
what are ganglion cells surrounded by
flattened satellite cells (fibroblasts)
what is the perineurium
surrounds several axons in order to create a fascicle
what is the epineurium
surrounds several fascicles
what is the endonerium
surrounds individual nerve fibres
what is found in the lateral part of the spinal cord grey matter
autonomic motor neurons
what is found in the anterior part of the grey matter in the spinal cord
somatic motor neurons
what is found in the posterior horns of the grey matter in the spinal cord
interneurons (reflexes)
what is found in white matter in the spinal cord
ascending and descending tracts
mostly paired and decussate
what is found in anterior white matter columns
motor
what is found in lateral white matter columns
motor or sensory
what is found in dorsal white matter columns
sensory
where is the median fissure
anterior
where is the median sulcus
posterior
what is the histological appearance of motor neurons in the spinal cord
multipolar cell bodies are large and found in the ventral horn large pale staining nucleus prominent nucleolus nissl bodies
can peripheral nerves be repaired
yes
CNS axons cannot
what is Wallerian degeneration
after trauma the PNS and CNS repairs by clearing debris and lays the foundation for regrowing nerve fibres
does not work properly in the CNS, also inhibitory factors in the environment contributing to failed repair
describe the process of Wallerian degeneration in the PNS
injury causes fragmentation of the axon and myelin sheath
schwaan cells become reactive and proliferate
macrophages phagocytose debris
schwaan cells express growth factor and form bands of Bungner
nerve fibres grow towards the bands
nerve fibres reconnect with end organs and are remyelinated by schwaan cells
Why does Wallerian degeneration fail in the CNS
inflammation
myelin debris is not completely removed
glial scar is formed by reactive astrocytes astrocytes
regrowth of axons is inhibited by myelin debris and glial scar
a cystic cavity forms
lack of growth promoting molecules and an inhibitory environment
may have reactive end bulbs
oligodendrocytes > myelin debris
astrocytes > glial scar
describe reactive astrocytes after injury
hypertrophy
expression of inhibitory molecules and normal molecules which forms a glial scar which the axon cannot pass through
where are glial cells segregated into CNS or PNS
glial limiting membrane at the dorsal root entry zone
what is the substantia gelatinosa
a mass of gelatinous gray matter that lies on the dorsal surface of the dorsal column and extends the entire length of the spinal cord into the medulla oblongata and transmits painful sensory information.
what is the gracile fasculus
carries information from the lower limbs
found in the posterior column medial lemniscus pathway
