histology nervous system

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histology nervous system
2011-09-08 09:51:27
histology nervous system

MS1/Mod 1: histology; nervous system
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  1. When are neurons derived embryologically?
    1-2mos after conception from neurectodermal cells
  2. nissl substance
    rER in neurons
  3. perikaryon characteristics
    • nissl
    • golgi
    • lipofuscin granules
    • nucleus/nucleolus
  4. axon hillock
    • void of rER
    • voltage dep channels
    • origin of AP
  5. subneural clefts
    folds in axon terminal; gives increased surface area
  6. varicosity
    swelling along length of axon or nerve terminal region; has synaptic vesicles but no well formed synapse; transmitter released to diffuse to target tissue (ANS)
  7. neuropil
    mass of lgly unmyelinated axons and dendrites w/in gray matter of CNS; contains neuronal cell bodies
  8. astrocytes
    • lgst glial cell
    • make GFAP
    • can have cell processes that terminate around capillaries
    • foot processes cover non-synaptic surfaces of neurons
  9. astrocyte functions
    • neuronal support and regulation
    • reuptake and metabolism of nt
    • maintenance of blood-brain barrier and scar formation after CNS trauma
  10. gliosis
    glial cell reactive process
  11. GABA
  12. oligodendrocytes
    metabolically active (lots rER) w/ numerous cell processes ending in myelination of numerous axons
  13. oligodendrocyte function
    • produces myelin w/in CNS
    • provides myelin sheath to mult axons
  14. microglia
    • sm cells w/ dense nuclei
    • mesodermal origin; from monocytes
  15. microglial function
    phagocytic w/in CNS
  16. ependymal cells
    epithelium lining ventricular system of CNS
  17. choroid plexuses
    modified ependyma + fenestrated capillaries; extend into ventricles for CSF prod
  18. blood brain barrier
    astrocyte foot process + basement membrane + endothelial cell
  19. Schwann cell
    • neural crest derivative
    • PNS neural glial cell
    • myelinates axons in PNS
  20. mesaxon
    linear junction at which two sides of Schwann cell come together after ensheathing axon
  21. Incisure of Schmidt-Lanterman
    cytoplasm filled channels in flattened Schwann cell cytoplasm; appear as clefts
  22. Incisure of Schmidt-lanterman function
    nutritive support to inner layers of myelin sheath
  23. endoneurium
    surrounds ind axons/myelin
  24. perineurium
    surrounds fascicle of nerve fibers
  25. epineurium
    surrounds groups of nerve fascicles
  26. Wallerian degeneration
    degenerative changes in axon/myelin distal to site of nerve injury; due to loss of continuity w/ cell body of neuron
  27. chromatolysis
    displacement of Nissl substance to periphery of cell body
  28. segmental degeneration
    loss of Schwann cells
  29. nerve injury and degeneration
    • 1. nerve transection
    • 2. chromatolysis
    • 3. prolif and act of Schwann cells distal to site of injury; forms pathways for nerve sprouts
  30. neurite-promoting factors
    laminn and fibronectin; helps axon grow back (only if myelin tube can be reformed following injury)