Flashcards in Central Nervous system Deck (10)
Differentiate between grey matter and white matter
1. grey matter: neuron cell bodies located here, glial cells, axons, and dendrites. fiber rich regions between cell bodies are called neuropil
2. white matter: long distance myelinated axon tracts. Astrocytes and oligodendrocytes are also present
Describe the characteristics of synapses and spines.
-pre-synaptic component, characterized by presence of synaptic vesicles, the active zone: site of synaptic vesicle fusion and neurotransmitter release
-post-synaptic component: found of dendrites, cell bodies, or axons
-spines: small protrusions from dendritic staff where majority of excitatory glutamatergic synapses are found
What are the characteristics of astrocytes?
-stellate cells that express glial fibrillary acidic protein (GFAP) and numerous processes. vimentin and intermediate filaments.
-function: maintain extracellular environment of CNS, regulate concentration of ions, clear excess glutamate, enhance neuronal ability to combat oxidative stress.
-have endfeet: forms glia limitans at brain surface and around blood vessels
-reactive gliosis: hypertrophy of cell body, increased growth of processes, increase in GFAP expression and proliferation-->limit neuronal injury or form glial scar to limit axonal regeneration
What are the characteristics of oligodendrocytes?
-myelin formation in CNS
-can myelin ate multiple axons
-late event in CNS development
What are the characteristics of microglia cells?
-resident macrophages of the brain, identify and phagocytose infectious agents that gain access to the CNS
-motile, can sample and remodel local environment
-possible participation in synaptic pruning
-removal of dying cells and debris
Describe the basis of the blood brain barrier
-formed by endothelial cells of capillaries-prevents large or hydrophilic molecules from penetrating brain parenchyma
-tight junctions, limited vesicular transport, high mitochondria number
what are the circumventricular organs?
-circumventricular organs: interrupted BBB
1. median eminence and neurohypophysis-invovled in regulation of pituitary hormones
2. area postrema-in medulla-chemoreceptor trigger zone for vomiting-detect blood borne substances
Describe the characteristics of ependymal cells and the choroid plexus
-ependymal cells: ciliated simple cuboidal epithelium lining ventricles and central canal of spinal cord
-cilia assist in circulation of CSF through ventricles
-Choroid plexus made of ependymal cells- they have tight junctions and forms blood-CSF barrier
-active transport of Na+ -produces most of CSF
What is the difference between CT and MRI?
-uses ionizing radiation and forms cross sectional images. useful in evaluation of trauma, stroke, in emergency setting. but has poor CNS tissue contrast
MRI=magnetic resonance imaging
-detects RF signal from H nuclei in magnetic field
-optimal imaging of CNS
-many sequences possible