Neuron Injury

Question 1

NEURON INJURY:

if die quickly

acute injury
- if (hours) survival = describe, chromatin
- if imminent death = describe nucleus & cytoplasm, chromatin

chronic - describe, chromatin

axon - duration, describe
astrocytes - lead to (2), cytoplasm, scar
oligodendrocytes - cytoplasm, nuclei, if severe
microglial

Answer 1

• if die quickly: no changes
• axon: 24-48h changes, swollen
• astrocytes: lead to hyperplasia & hypertrophy, vacuolation of cytoplasm, gliotic scar
• oligodendrocytes: vacuolation of cytoplasm, nuclei shrink, if severe=demyelination
• microglial: activated

acute injury
- if 6-12h survival = swollen, chromatolysis (nucleus & ribosomes move to cell periphery)
- if imminent death: nucleus shrink, vacuolation of cytoplasm, hyperchromatin

chronic injury
- everybody shrink
- hyperchromatin

Question 2

NEURON INJURY: Cerebral Edema

vasogenic, cytotoxic, interstitial - patho, location, ECF volume

Answer 2

vasogenic
- inc permeability
- white matter
- inc ECF

cytotoxic
- broken Na K
- both gray & white matter
- dec ECF

interstitial
- CSF block
- periventricular white matter
- inc ECF

Question 3

NEURON INJURY:

PNS - how myelination, max folds, light minor vs. dark major dense line (component & inner/outer), schmidt-lanterman (no what d/t what)

CNS - how myelination, max fibers

nonmyelinated - no (1), example (2)

myelinated/non - saltatory vs. point to point conduction

Answer 3

PNS
- myelinate via schwann (max 50)
- light minor dense line (outer lipid), dark major dense line (inner protein)
- schmidt-lanterman: no dark major d/t many schwann

CNS
- myelinate via oligodendrocytes (max 60)

nonmyelinated
- no nodes of ranvier
- ex: postganglionic of ANS, sensory of pain
- point to point conduction (since saltatory is via nodes)

Question 4

NEURON INJURY:

sensory ganglia - where, cont with, polar, myelinated, surrounded

autonomic ganglia - (2), polar, surrounded by

Answer 4

sensory ganglia
- neurons outside nervous system
- cont with peripheral nerve
- unipolar; unmyelinated
- surrounded by capsular/satellite cells

autonomic ganglia
- sympathetic & parasympathetic
- multipolar
- surrounded by capsular/satellite cells

Question 5

NEURON INJURY: PNS

reaction
axon
- at distal: spread direction, wallerian, D1/3/4 (1.2), band fiber (what + signify), if no band = (?)
- at proximal: where

cell body
- most when, chromatin
- synaptic stripping: (1), dendrites become (1.1)

recovery
- axon: depend on (4), diameter, NCV, mm/day, prox/distal muscle first, sensation order (5)
- cell body: nucleus, nucleolus, synthesis, describe, what reappears

conduction velocity x axon cross-section

Answer 5

REACTION
axon
- conduction velocity DP axon cross-section
at distal segment
- spread distally, wallerian occurs
- D1= swell, D3 & D4 = phagocyte by macrophage & replaced by schwann
- band fiber: endoneural sheath of schwann; if present = regeneration; if absent = axon replaced by fibroblast into fibrous tissue
at proximal segment
- as far as first node of ranvier

cell body
- most changes within 2 days
- chromatolysis
- synaptic stripping: vesicles leave; dendrites become schwann (PNS) & astrocytes (CNS)

RECOVERY
axon
- depend on: presence of band fiber, if gap is not filled, if muscle remains innervated, no infection
- 80% of original diameter, slower NCV, 2-4 or 3-5mm/day
- prox muscle first
- deep pressure > unlocalized superficial > vasomotor > temp > localized

cell body
- nucleus to center, nucleolus to side, nissl reappear
- ribosome & protein synthesis

Question 6

NEURON INJURY: CNS

axon - phagocyte, what replace, recovery duration, scar

Answer 6

• phagocyte by microglial
• replaced by astrocytes = glial scar
• recovery at 2 weeks then cease