Nervous System Cell and Tissue Response to Injury

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Author:
jknell
ID:
193998
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Nervous System Cell and Tissue Response to Injury
Updated:
2013-01-20 19:35:54
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MBB II
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MBB II
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  1. Histologic Stains
    • -H&E: basophilic (blue), eosinophilic (pink)
    • -Trichrome: inclusions
    • -Nissl: stain all neurons
    • -Luxol Fast Blue: stains myelin blue
    • -Silver: only affects selected neurons
  2. Neuron Reaction to Injury
    • 1. Death
    • 2. Inclusions
    • 3. Regeneration
  3. Neuronal Cell Death
    • Necrosis
    • -pathologic
    • -inflammatory process
    • -intracellular components extravasate

    • Apoptosis
    • -programmed cell death, often physiologic
    • -Cell and nuclear shrinkage
    • -membrane blebbing
    • -nuclear fragmentation
    • -pyknosis (basophilia)

    • Autophagy
    • -cell consumes it's own contents during nutrient deprivation
    • -can either recover or undergo cell death
  4. Neuron Inclusions
    • -Neurofibrillary tangles
    • -Lewy bodies
    • -Huntingtin inclusions
    • -Pick bodies
    • -Cowdry type A inclusions
  5. Neurofibrillary Tangles
    • -Alzheimers

    • A) Pink Inclusion in live neuron
    • B) Silver stain of neurofibrillary tangle
    • C) Tau stain of neurofibrillary tangle
  6. Lewy Bodies
    • -made of alpha-synuclein
    • -found in cytoplasm of substantia nigra cells in patients with Parkinson's

    • Large pink inclusion, with clear halo
  7. Huntingtin Inclusion
    • -intranuclear inclusion of huntingtin protein
    • -seen in patients with Huntingtin disease
    • Stain dark on ubiquitin stain
  8. Pick Bodies
    • -Cytoplasmic inclusions
    • -found in Pick's disease (frontotemporal dementia)
    • -shown well with silver stain
  9. Cowdry type A inclusion
    • -viral inclusions found in herpes viral infections
    • -found in neurons and glial cells
  10. Neuron Regeneration - PNS
    • 1. At zone of Injury
    •      -ends seal off

    • 2. Proximal Segment
    •      -dies back a little bit

    • 3. Distal Segment
    •      -Wallerian degeneration (fancy word for   death)
    •      -connective tissue sheath stays intact
    •      -this triggers Schwann cells to proliferate and secrete growth factors
    •      -this promotes regeneration
    •      -axons use the same molecular signals as during development to target the right place (from Schwann cells)
  11. Neuron Regeneration - CNS
    • 1. At zone of Injury    
    •      -ends seal off
    •      -astrocytes make a scar
    •      -glial scar interferes with regrowth

    • 2. Proximal Segment
    •      -dies back a little bit

    • 3. Distal Segment
    •      -Wallerian degeneration (fancy word for death)
    •      -no schwann cell proliferation

    CNS NOT AS READY TO REGENERATE
  12. Aberrant Regeneration
    • -proximal segment regeneration does not correctly target distal segment
    • -neuroma formation
  13. Oligodendroglial reaction to injury
    -Primary demyelination

    -vs Secondary demyelination (due to direct damage of the axon)
  14. Astrocytic reaction to injury
    • -hypertrophy
    • -hyperplasia
    • -cytoplasmic swelling

    • -glial scar
    • -GFAP stain

  15. Microglial cell reaction to injury
    • -macrophages
    • -clear out dead neurons
    • -microglial nodules
    • -ROD CELLS: associated with viral encephalitis
  16. Vascular cell and vessel response to injury
    -capillary proliferation to bring more MP to the site of injury
  17. Meningeal cell response to injury
    -pia and arachnoid can fibrose

    • -disorders of CSF flow
    • -polyradiculopathy (effects CNs or cauda equina)
  18. Tissue response to injury
    • 1. Edema
    • 2. Inflammation
    • 3. Tissue necrosis
    • 4. Demyelination
    • 5. Mass effect
    • 6. Spongiform changes
  19. Cerebral Edema
    -increased water content of the brain

    • 1. Vasogenic
    • 2. Cytotoxic
    • 3. Interstitial

    4. Congestive brain swelling
  20. Vasogenic Edema
    • -most common form of edema
    • -damage to BBB
    • -affects white matter more than gray
    • -white matter appears pale

    -Tx: mannitol, GCs
  21. Cytotoxic Edema
    • -"cellular" edema
    • -water moves from the interstitium into the cells
    • -usually due to failure of N/K ATPase
    • -no or little increase in brain volume
  22. Interstitial Edema
    • -"hydrocephalic" edema
    • -increased CSF pressure in the ventricles causes Na and water to leak across the ependymal cells in to the white matter
  23. Congestive Brain Swelling
    • -most commonly caused by closed head injury
    • -hypermia (increased blood flow into brain)
    • -more common in children than adults
    • -significant morbidity and mortality
  24. Cerebral Inflammation
    • -Perivascular cuffing
    • -inflammatory infiltrates
  25. Cerebral Necrosis
    • 1. Coagulative
    • 2. Liquefactive
    • 3. Caseous
    • 4. Fibrinoid
    • 5. Dystrophic calcification
  26. Coagulative Necrosis
    -tissue architecture preserved
  27. Liquefactive Necrosis
    • -creamy yellow
    • -common in CNS
  28. Caseous Necrosis
    • -cheesy
    • -TB
  29. Fibrinoid Necrosis
    • -autoimmune vasculidites
    • -antigen-antibody complexes deposited in arterial walls
  30. Dystrophic Calcification
    -tissue that remains after necrosis may become calcified
  31. CNS demyelination
    • -due to disorder of oligodendroglial cell or a disorder of the myelin
    • -grey-tan area
    • -firmer
  32. CNS Mass Effect
    • -may result in ischemia, edema, inflammation
    • -over time may result in atrophy
    • -white matter more susceptible
  33. Spongiform Changes
    • -uncommon
    • -vacuoles in neurons, glial cells or in the neuropil
    • -prion disorders
    • -leukodystrophy
    • -B12 deficiency
  34. Peripheral nerve response to injury
    • 1. Segmental demyelination
    • 2. Wallerian degeneration
    • 3. Axonal degeneration
  35. Segmental demyelination
    • -loss of myelin sheath with sparing of underlying axon
    • -most commonly due to compression of a peripheral nerve
    • -recovery over weeks to days
  36. Wallerian degeneration
    -distal axon death
  37. Axonal Degeneration
    • -dying back of the axon starting distally
    • -usually due to a disorder of the nerve cell body
  38. Remyelination
    • -new myelin segments are thinner and shorter
    • -onion bulb appearance
    • -can be enlarged to palpation
  39. Muscle response to injury
    • -Changes in fiber size
    • -Abnormalities in the distribution of fibers
    • -Changes in sarcolemmal nuclei
    • -Degeneration and regeneration
    • -Inflammation
    • -Fibrosis
  40. Changes in fiber size
    -Type 2 fiber atrophy: problem outside the muscle, due to disuse
  41. Abnormalities in the distribution of fibers
    • 1. Small group atrophy
    •      -typically due to denervation
    •      -affects a small number of adjacent fibers

    • 2. Large group atrophy
    •      -large group or even entire fascicles
    •      -indicates denervation

    • 3. Perifasicular atrophy
    •      -atrophic fibers at margins of fascicles
    •      -inflammatory myopathies

    • 4. Type grouping
    •      -large groups of one fiber type next to large groups of another fiber type
    •      -due to chronic denervation and reinnervation
  42. Changes in sarcolemmal nuclei
    • -internal nuclei (myopathy)
    • -nuclear chains (myopathy)
  43. Degeneration and Regeneration
    • -necrosis: pale staining, phagocytes
    • -regeneration: basophilic, associated vesicular nuclei
    • -Fiber splitting:?
  44. Inflammation
    -if inflammation is perivascular then it typically occurs in the perimysial region between the fascicles
  45. Fibrosis
    -seen in myopathies or less commonly neurogenic atrophies

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