CNS Flashcards
what are meningothelial cells supported by and what is their function
supported by connective tissue and have protective function
where are the meninges located
outer layer of brain and cord in CNS
what are the 3 layers of the meninges
dura mater, arachnoid mater, pia mater
describe the dura mater
thick layer of dense CT internally lined by mesothelium
what does the dura mater fuse with in the cranium
periosteum of the skull
what is the subarachnoid space lined with
flattened mesothelial cells
what is the pia mater adhered to
the surface of the brain and cord
what makes up the leptomeninges
pia and arachnoid mater
what are neurons in the CNS derived from
neuroectodermal cells of the neural tube
what is the spatial relationship between grey matter and white matter in the cerebral cortex
gray matter is peripheral and white matter is central
what does peripheral gray matter contain
neuron cell bodies, dendrites, and axons
what does central white matter contain
myelinated axons
what are neuroglia and what is their function
-they are highly branched support cells in CNS
-they function to provide structural and metabolic support for neurons
what are the 4 types of neuroglia
oligodendrocytes, astrocytes, microglia, and ependymal cells
what are oligodendrocytes and where are they located
make myelin sheaths in the CNS, located mostly in white matter
what are astrocytes and what is their function
most highly branched, largest neuroglial cells
- provide structural and metabolic support and aid in tissue repair following injury
what are microglia and what is their function
-phagocytic, fixed-tissue macrophages, smallest neuroglial cells
-function: immune
where are ependymal cells found and what is their function
-cuboidal epithelium lining ventricles and central canal of spinal cord, ciliated for reabsorption of CSF
-job is to circulate and reabsorb CSF to prevent accumulation
what secretes CSF
the choroid plexus
what is the choroid plexus
vascular structure arising from walls of ventricles of the brain
-contains ependymal cells that secrete CSF
what is the function of CSF
acts as a shock absorber
what does the neocortex include
sensory, motor, and association areas
what are the folds of the cerebrum called
gyri
what are nuclei in the cerebrum
clusters of neuron cell bodies that form islands of gray matter in the cerebrum and cerebellum
what are the neuroglial cells in gray matter
microglial cells, astrocytes, and neuron cell bodies
what neuroglia does the white matter contain
oligodendrocytes
what are tracts in gray matter
axons leading in and out that are grouped in bundles
how do you distinguish neuron cell bodies in a slide of gray matter
they are triangular with a small nucleus attached and a white halo
what are the 6 layers of cortical neurons from superficial to deep
plexiform, external granular, external pyramidal, internal granular, ganglionic, fusiform
what are pyramidal cells
pyramid shaped neurons with long, slender axons carying in size from small to large
-most common neuron cell body
what are betz cells
largest pyramidal cells that are upper motor neurons in motor cortex
what are stellate (granule) cells
small start shaped neurons with short axons and dendrites
what are cells of martinotti
small neurons with long, horizontal axons
what are fusiform cells
vertically oriented, spindle shaped neurons with vertical axons
what are horizontal cells of cajal
horizontally oriented, spindle shaped neurons with horizontal axons
-least common type, only found in superficial layer
what are the 5 types of cortical neurons
-pyramidal cells
-stellate
-cells of martinotti
-fusiform cells
-horizontal cells of cajal
what does the plexiform layer contain
mostly dendrites and axons of cortical neurons
what does the outer granular layer contain
large numbers of small pyramidal and stellate cells
what is in the pyramidal cell layer
large cells located deep in layer, martinotti cells
what is in the inner granular layer
densely packed stellate cells
what is in the ganglionic layer
large pyramidal cells, stellate cells, and cells of martinotti
what is in the multiform cell layer
small pyramidal cells, cells of martinotti, stellate cells and fusiform cells
what is the function of the cerebellum
coordinates muscular activity, posture and equilibrium
what are the folds of the cerebellum called
folia
what are the layers of the outer cerebellar cortex
outer molecular layer and inner granular layer
what does the outer molecular layer of the cerebeullum contain
few neurons and large numbers of unmyelinated axons
what does the inner granular layer of the cerebellum contain
highly cellular, very basophilic, contains large number of neuroglial cells and small neurons called granule cells
what are purkinje cells
specialized neurons that function in coordination and equilibrium. separates the molecular and granular layers in the cerebellum
what is the ventral median fissure
a line that bisects the ventral side of the spinal cord
what does the central canal contain and what is it lined with
contains CSF and is lined with ependymal cells
what is the spatial relationship between the grey matter and white matter in the spinal cord
the grey matter is located centrally, and the white matter is located peripherally
what does grey matter in the spinal cord contain
cell bodies and axons
what connects the 2 dorsal horns and 2 ventral horns
a central commissure
where is the central canal found
in the central commissure
how does the PNS respond to injury
connective tissue scar and schwann cells form bridge between severed ends of nerve
how does an axon regenerate in the PNS
if the gap is not too big:
1. schwann cells mutliply to physically bridge the gao
2. nerve axon sprouts neurites from proximal stump
3. neurites grow into distal stump; contact reestablishes function
what is anterograde (wallerian) degeneration
loss of an axon
what is retrograde degeneration
loss of a cell body
what is chromatolysis
when a cell body is injured the neuron swells and becomes brightly eosinophilic and loses Nissl substance
how does the CNS respond to injury
neuroglial cells multiply, scar tissue proliferation from glial cells prevents regeneration and physically blocks contact between cell body and axon
what happens in ALS (neurons)
due to death of motor neurons controlling voluntary muscle movement
what is meningitis
inflammation of the meninges,
what is encephalitis
inflammation of the brain
what is myelitis
inflammation of the spinal cord
what is encephalomyelitis
inflammation of brain and cord
what is meningoencephalitis
inflammation of the meninges and brain
what happens in viral meningitis
transient lymphocytic infiltrate
what happens in bacterial meningitis
neutrophilic infiltrate and may be life threatening
what happens in polio
affects alpha motor neurons of ventral horn of spinal cord
-lower motor neuron paralysis and subsequent muscular atrophy
-eradicated
what happens in parkinsons disease
neurodegenerative disease characterized by muscular tremor due to death of neurons in substantia nigra
-decreased dopamine production in brain
what happens in alzheimers disease
form of dementia characterized by neural plaques and fibrillary tangles within cortex
what is MS and who does it affect
- an autoimmune, inflammatory, demyelinating disease of the CNS
-antibodies destroy myelin sheaths around axons which leads to plaque formation
-affects women 20-40 y/o
what is guillain barre syndrom
immune-mediated demyelination in PNS
- often initiated by infection ->progressive weakness in peripheral muscles
