histology of CNS Flashcards
what are glia?
support cells, involved in:
conduction speed
repair
neurotransmitter maintenence
what is neuropil
network of interwoven nerve fibers and glial filaments
what is the basic anatomy of a typical neuron
large cell body
long, myelinated axon
lots of branching dendrites
what is a terminal arborization
distal end of an axon
what is telodendria
a dilation at the branch end of an axon where it contacts postsynaptic cell
what is the most common neuron in the CNS
multipolar
where are bipolar neurons found
retina
olfactory mucosa
inner ear
what neuron type is found within the dorsal root and cranial ganglia
unipolar/pseudounipolar
what do anaxonic neurons do?
regulate local electrical changes of adjacent neurons
DO NOT PRODUCE APs
which axonal transport system carries material from the nerve cell body to the periphery?
anterograde transport
what mechanism is used for anterograde transport
ATP-dependent kinesin (microtubule associated motor protein)
which axonal transport system carries material from the axon terminal/dendrites to the cell body?
retrograde transport
what mechanism is used for retrograde transport
dynein (microtubule associated motor protein)
is retrograde transport slow or fast
fast only
what molecules are carried via slow transport
tubulin and actin molecules
neurofilament proteins
what organelles are found at the presynaptic terminal bouton
mitochondria,
synaptic vesicles
how does current flow occur in an electrical synapse
gap junctions
what is the function of connexon proteins in an electrical synapse?
permit diffusion of small molecules
electric current flow
what are the four types of glial cells
astrocytes
oligodendrocytes
microglial cells
Ependymal cells
what are the structural characteristics of an astrocyte?
lots of long, branching processes
reinforced by GFAP
what is the function of astrocytes
regulate extracellular [ions]
support neurons
fill in tissue damage (astrocytic scar)
what is the function of the perivascular feet of astrocytes?
cover capillary endothelial cells, modulate blood flow
what is the function of oligodendrocytes?
wrap around axons => cytoplasm leaves => myelin
how do oligodendrocytes appear on histo slide?
unstained cytoplasm
round, condensed nucleus
what are oligodendrocytes derived from embryologically
neuroepithelium
what is the counterpart of oligodendrocytes in the PNS?
Schwann cells
what are the structural characteristics of ependymal cells
columnar/cuboidal cells lining ventricles of the brain and central canal of spinal cord
apical end w/ cilia and microvilli
no basal lamina
what is the function of ependylmal cells
facilitate CSF movement
absorption
what are the structural characteristics of choroid plexus
folded
highly vascular
roofs 3rd and 4th ventricles
thin layer of pia covered w/ ependymal cells
what is the function of choroid plexus
removes H2O from blood, releases it to CSF
what are microglia derived from
monocytes
what is the function of microglia
remove damages/inactive synapses
IMMUNE DEFENSE of CNS
where is the central canal of the spinal cord?
within the central commissure of grey matter
what is found within the central canal
CSF
lined by ependymal cells
what glial cells are found in abundance within the grey matter of the spinal cord?
astrocytes
what glial cells are found in abundance within the white matter of the spinal cord?
oligodendrocytes
what are the three layers of the cerebellar cortex?
molecular layer
purkinje cells
granular layer
which layer of the cerebellar cortex contains small, densely packed neurons and little neuropil
granular layer
which layer of the cerebellar cortex has a lot of neuropil and scattered cell bodies
molecular layer
what are the 6 cortical layers?
I. plexiform II. small pyramidal cell layer III. layer of medium pyramidal cells VI. granular layer V. large pyramidal cell layer VI. polymorphic layer
which cortical layer consists mostly of parallel fibers, neuroglial cells and horizonal cells of cajal
plexiform layer (I)
in what cortical layer are there very large pyramidal cells
large pyramidal cell layer (V)
what cortical layer is characterized by many small granule cells
granular layer (IV)
how does the middle cell layer of the hippocampus differ from that of the dentate gyrus
the middle cell layer of the hippocampus contains pyramidal cells
the dentate gyrus has dentate granule cells with round cell bodies
what is the hilus?
the region where the head of the hippocampus touches the dentate gyrus
what is the role of mossy cells within the hilus?
receive input from fibers of dentate granule cells => relay signals to other dentate cells
what gyri may are markedly thinned in alzheimers dz?
gyri of the frontal and temporal lobes
where are amyloid plaques?
in the cortex of pt’s w/ alzheimers
abnormal accumulation of tau results in what hallmark of alzheimer’s
neurofibrillary tangles
what neural cell is associated with GFAP
astrocytes
what cells are the macrophages of the CNS?
microglia
what is the key difference between Schwann cells and oligodendrocytes
each oligodendrocyte myelinates MULTIPLE axons
each Schwann cell myelinates A SINGLE axon
