Neuropath- Part 2

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Mawad
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308904
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Neuropath- Part 2
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2015-10-05 11:07:46
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vetmed neuropath
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vetmed neuropath
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  1. Mechanical separation of an axonal process from the proximal axon and neuron cell body.
    Wallerian degeneration
  2. The characteristic sequence of events following Wallerian degeneration. (3)
    death of isolated axonal segment, removal of the debris, and attempts at replacement from the proximal (viable) axon segment
  3. With Wallerian degeneration, within minutes of degeneration and necrosis of the distal axon, there is disruption of _________; within hours, there are ____________ and ____________.
    neurofilaments; irregular swellings; fragmentation of the axonal process
  4. With Wallerian degeneration, ______________ degeneration occurs for a short distance up the viable axonal process.
    retrograde axonal
  5. With Wallerian degeneration, ___________ occurs 2-10 days post injury.
    phagocytosis of debris
  6. With Wallerian degeneration, _____________ commences 2-3 weeks post injury.
    attempts at regeneration
  7. Axonal regeneration in the PNS occurs by...
    axons sprouting from the stump and elongation through the vacant neurilemmal tract.
  8. Axonal regeneration in the CNS is inhibited by ____________; it is also prevented by lack of a ____________.
    CNS myelin-associated protein; neurilemmal tract
  9. Regeneration failure in the PNS occurs due to... (2)
    displacement of ends or mass obstruction of the neurilemmal tract.
  10. Failure of reinnervation in the PNS is more likely when...
    distance to be covered is great.
  11. How does a neuroma develop?
    failure of reinnervation in the PNS: collateral sprouts form as the regenerating axon attempts to find a neurilemmal tract
  12. Failure of a neuron to metabolically support the axonal process due to defective axonal transport.
    neuraxonal dystrophy
  13. The cause of neuraxonal dystrophy is thought to be _________.
    idiopathic
  14. Three ways that neuraxonal dystrophy can occur.
    disruption of slow antegrade transport, disruption of fast antegrade transport, disruption of retrograde transport
  15. Disruption of slow antegrade transport causes neuraxonal dystrophy by causing swelling in the ___________ due to ____________; the __________ stays intact.
    proximal segment; accumulation of neurofilaments; distal segment
  16. Disruption of fast antegrade transport causes neuraxonal dystrophy by causing a more ________________ without extreme _________.
    acute axonal degeneration; swelling
  17. Disruption of retrograde transport causes neuaxonal dystrophy by causing accumulation of __________ at the ___________ with ____________ of the fiber.
    organelles; distal end (distal swelling); dying back
  18. Disruption of retrograde transport is expressed as __________.
    distal axonopathy
  19. A non-specific reduction in dendritic complexity resulting from non-specific affects of disease or aging.
    dendritic atrophy
  20. Non-specific neuronal reaction to injury in which there is a central loss of Nissl substance.
    central chromatolysis
  21. The initial change of central chromatolysis occurs within _________; this change is...
    3 days; ribosomes dissociate from the fragmenting endoplasmic reticulum.
  22. Central chromatolysis occurs during a cellular state of...
    increase protein synthesis and AA uptake.
  23. Accumulation of macromolecules resulting from states of increased/abnormal production or decreased elimination.
    neuronal inclusion
  24. What are the different kinds of neuronal inclusions? (4)
    inclusions associated with membrane recycling, inclusions of virus infection, inclusions associated with cellular degeneration, incidental inclusions
  25. Autofluorescent lipopigment resulting from normal wear and tear; poorly digestible products progressively accumulate within cells that occurs within increasing age.
    Lipofuscin
  26. Lipofuscin inclusions in a young animal suggests...
    pathologic increases in membrane turnover.
  27. Defective lysosomal enzymes function associated with lysosomal storage disease results in _________________ and __________.
    accumulation of the substrate for the enzyme; lysosomal distension
  28. Inclusions of viral infection are formed by the accumulation of... (5)
    virus particles, defective virus particles, viral protein, virus-induced host protein, or cellular protein who structure/solubility has been altered.
  29. Inclusions associated with cellular degeneration are called ___________; in the process of degeneration, ___________ may accumulate and be focally condensed by ____________.
    cytosegrasomes; macromolecular complexes; collapse of the cytoskeleton
  30. Cytosegrasomes are seen with some _______________.
    degenerative disorders
  31. Eosinophilic cytoplasmic inclusions that resemble rabies viral inclusions that consist of collapsed lamella of the roughER.
    Pseudo-negri bodies
  32. What is the significance of incidental inclusions?
    they can be mistaken for inclusions associated with disease.
  33. In order to confirm viral inclusions, also look for...
    other hallmarks of viral infection, such as inflammation and selective necrosis (to rule out incidental inclusions).
  34. Loss of homeostatic capabilities resulting in cell death.
    neuronal necrosis
  35. Due to the ________________, general cellular insults may selectively kill neurons.
    high metabolic rate and specialization
  36. The progression from degeneration to necrosis results in _____________ on HE stain.
    increased eosinophilia
  37. Necrotic neurons are known as ___________.
    dead reds
  38. Describe how necrosis causes increased eosinophilia on HE stain.
    drop in cytosolic pH--> protein denaturation--> increased eosinophilia--> dissociation of ribosomes from the ER and degradation of rRNA--> increased eosinophilia
  39. Nuclear changes associated with neuronal necrosis include... (4)
    margination along plasmalemma, decreased staining intensity (karyolysis), fragmentation (karyorrhexis), condensation (pyknosis)
  40. In response to tissue injury, microglial cells numbers are greatly complemented by _____________.
    monocytes from circulation
  41. Describe the nuclei of inactive microglia.
    small microchromatic (dark) nuclei
  42. Describe the nuclei of activated microglia?
    rod-shaped nuclei that are often bent
  43. Microglia that have been activated are filled with ___________, particularly _________; they often exhibit ___________ of the cytoplasm; these cells are called ____________.
    poorly digestible material; lipid; vacuolar distension; "glitter cells"
  44. Focal increase in microglial number in response to a selective insult.
    glial nodule
  45. Diffuse increase in microglial number secondary to a widespread selective insult or a non-selective insult.
    Microgliosis
  46. The response to tissue injury is ____________ of astrocytes.
    hypertrophy and/or hyperplasia
  47. True fibrosis in response to tissue destructiononly occurs in association with __(2)__.
    meninges or vascular adventitia
  48. Activation of astrocytes is accompanied by increased expression of _____________ and an increase in ___________, resulting in ___________.
    glial fibrillary acidic protein (GFAP); cell processes; fibrous astrocytes
  49. ____________ can mark the presence of underlying tissue damage.
    Astrocytic reactivity
  50. Focal increases in astrocytes that follow selective insult.
    glial scars
  51. Increased number of astrocytes where the stimulus is widespread.
    astrocytosis
  52. Injury to oligodendroglial and schwann cells results in swelling and fragmentation of ___________, followed by _________________; _____________ results in impaired ____________.
    myelin; phagocytosis of debris by macrophages; demyelination; saltatory conduction
  53. Primary demyelination occurs when...
    the initial myelin loss occurs where axons are intact
  54. What are possible etiologies of primary demyelination? (4)
    toxic, metabolic, viral, immune-mediated
  55. Secondary demyelination occurs when...
    the primary insult causes axonal loss, so that the oligodendrocyte or Schwann cell loses trophic influences required to sustain myelin formation.
  56. In addition to axonal damage, damage to ____________ may also result in loss of metabolic support of the myelin-producing cells, leading to secondary demyelination.
    astrocytes
  57. What are the determinants of remyelination? (2)
    persistence of the insult, location (CNS vs PNS)
  58. The ____________ makes remyelination much less common in the CNS; additionally, it is more successful in the PNS because...
    high axon:oligodendroglia ratio; mitotic potential of schwann cells is much greater than oligodendrocytes.
  59. Increased brain tissue water content.
    edema
  60. What is the significance of brain edema?
    it expands tissue volume, but the cranial vault limits potential for expansion--> increased intracranial pressure
  61. 4 etiologies of brain edema.
    vascular leakage, intracellular fluid accumulation, increased CSF pressure, toxic insult causing splitting of myelin
  62. Vascular leaking in the brain causes __________; it occurs because of loss of __________.
    vasogenic edema; BBB function
  63. With time, brain edema fluid tends to accumulate in _____________, regardless of its origin.
    white matter tracts
  64. Intracellular fluid accumulation causes ____________; fluid accumulates within ____________; selective insults, such as __(3)__ causes __(2)__.
    cytotoxic edema; astrocytes; hypoxia/bacterial exotoxin or salt toxicity; damaged ion pumps or rapid osmolality shifts (respectively)
  65. Combination of vasogenic and cytotoxic edema is called the __________.
    edema cycle
  66. With the edema cycle, primary endothelial injury leads to ________ edema and decreased ___________; this leads to __________ and _________ edema.
    vasogenic; tissue perfusion; tissue hypoxia; cutotoxic
  67. With the edema cycle, primary astrocytic insult leads to ________ edema and _____________; this causes ___________ and low ________; loss of __________ results in ___________ injury and __________ edema.
    cytotoxic; tissue volme expansion; vascular compression; flow; laminar blood flow; endothelial injury; vasogenic
  68. Increased CSF pressure causes _____________; can be secondary to __(2)__.
    transependymal edema; diminished flow (obstruction) or decreased resorption at the arachnoid granulations
  69. With transependymal edema, CSF is pushed into the ___________, separating ___________ from their source of metabolic support and causing loss of __________.
    periventricular white matter; oligodendrocytes; myelin
  70. The _____________  is a salient feature of hydrocephalus due to ____________.
    ventricular expansion; transependymal edema
  71. Edema caused by toxic insult to oligodendrocytes, causing splitting of myelin lemella.
    intramyelinic edema
  72. Intramyelinic edema may be caused by __(2)__ and results in __________.
    toxins or portal-caval shunts; primary demyelination
  73. Histologic changes associated with brain edema.
    polymicrocavitation/spongiform
  74. Polymicrocavitation on histopath reflects...
    fluid accumulation within astrocyte processes, b/w myelin lamella, and b/w cells.
  75. Fluid accumulates within astrocyte processes with ___________.
    cytotoxic edema
  76. Fluid accumulates b/w myelin lamellae with ___________.
    intemyelinic edema
  77. Fluid accumulates within b/w cells with __________.
    vasogenic edema
  78. What are sequelae to brain volume expansion and increased intracranial pressure? (5)
    asymmetry, flattening of gyri, ischemic brain necrosis, herniation, demyelination
  79. Flattening of gyri is sequela of increased intracranial pressure with ____________; asymmertry of the brain occurs with __________.
    generalized edema; localized edema
  80. With ischemic brain necrosis, swelling compresses __________; if severe and prolonged brain swelling is reduced therapeutically, ______________ can cause a severe ___________ edema.
    small caliber vessels---> ischemia; reperfusion of damaged vessels; vasogenic
  81. Herniation is often secondary to initiation of _________.
    the edema cycle
  82. What are areas of te brain where herniation commonly occurs with edema? (3)
    cinguated gyrus slips beneath falx cerebri, occipital cortex slips beneath tentorium cerebelli, cerebellar vermis herniated through foramen magna
  83. When the occipital cortex herniates and slips beneath the tentorium cerebelli, the herniateed portion compressed the ___________, which is displaced __________.
    midbrain; caudally
  84. When the cerebellar vermis herniates through the foramen magna, the __________ is compressed as a result.
    brainstem
  85. What is the significance of herniation in the brain?
    hemorrhagic infarction of the herniated section and/or the tissue compressed by the herniated segment
  86. Pathology consisting of enlarged ventricles and a very thin cortex.
    hydrocephalus
  87. With brain herniation, compression is sufficient to occlude ____________ but not ___________; therefore, tissue is ____________, called ___________.
    venous drainage; arteriolar supply; engorged ith blood; hemorrhagic infarction
  88. Brainstem compression by herniated cerebellum causes sudden death through...
    infarction of respiratory and cardiovascular centers.
  89. Demyelination is associated with _______________ edema.
    persistent white matter
  90. Demyelination due to persistent white matter edema underlies the ____________ that is associate with ____________ edema.
    periventricular atrophy; transependymal (ie. hydrocephalus)
  91. Death of a specific cell type.
    selective necrosis
  92. Death of all components of a tissue.
    pannecrosis
  93. With pannecrosis, __(2)__ may survive, resulting in __________.
    microglia and blood vessels; malacia (grossly apparent tissue softening)
  94. Determinants of selective vs pannecrosis. (3)
    metabolic burden/degree of specialization of target cell population, magnitude of insult, expression of protective factors in target population
  95. Cells that are #1 susceptibilty to necrosis. (2)
    neurons, oligodendroglia
  96. Cells that are #2 susceptibilty to necrosis. (1)
    astrocytes
  97. Cells that are #3 susceptibilty to necrosis. (2)
    microglia, endothelium
  98. Mild inults are more likely to induce _________, whereas qualitatively similar severe insult may cause __________.
    selective necrosis; pannecrosis
  99. Distribution or extent of necrosis varies depending on... (3)
    type of insult, differences in cellular expression of protective proteins, or the presence of neuronal "networks" that place all cells at risk.
  100. Heat-shock proteins mediate cell recovery by... (5)
    binding hydrophobic protein residues to prevent irreversible aggregation, mediate protein-refolding, mediate protein import into mitochondria, control enzymes, promote glucose uptake
  101. Neurons with __________ of HSP are most at risk for diverse insults.
    low basal and/or inducible levels
  102. Glutamate excitotoxicity leads to...
    enhances expression of selective neuronal necrosis.
  103. ___________ is the primary excitatory neurotransmitter in the brain.
    Glutamate
  104. The excitation signal in an excitable brain cell is terminated  by....
    active removal of glutamate from the synpatic cleft by astrocytes.
  105. With glutamate toxicity, excessive glutamate release occurs secondary to ____________, causing degeneration and necrosis of __________; ___________ can further predispose neurons to injury since glutamate uptake by astrocytes is _____________.
    tissue insult; post-synaptic neurons; low blood glucose; glucose-dependent
  106. Mechanism of excitotoxicity: NMDA receptors become refractory to the modulatory effects of ________ with prolonged ____________, resulting in excess ________ entry into the post-synaptic neuron; the high intracellular _______ activates enzymes that destroy the ___________ of the cell.
    Mg2+; stimulation; Ca2+; Ca2+; homestatic capabilities
  107. Glutamate toxicity increases the _____________.
    zone of tissue injury
  108. Diseases where excitotoxicity has been implicated. (5)
    ischemic injury, hypoglycemia, Alzheimer's dz, parkinson's dz, viral infections
  109. Resolution of pannecrosis consists of _________ mediating the clean-up, becoming laden with ___________, and ultimately forming a ___________. Astrocytes form a _________; the cavity becomes filled with _________.
    macrophages; myelin-derived fat; tissue cavity; glial scar; CSF

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