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13 Cards in this Set

  • Front
  • Back
what is a positive babinski sign indicative of? why and when does it occur?
pos babinski: running object down sole of foot results in dorsiflexion/ extension (hyperreflexia, hypertonia)
indicates UMN lesion (ex. corticospinal tract)
occurs after a period of hyporeflexia b/c LMN are not receiving stim from UMN
what does the babinski sign suggest in the role of the corticospinal tract?
that it may play a role in downregulating reflexes
what is the flexion/cross extension reflex?
R foot steps on pin (activated by cutaneous nociceptors)
ipsilateral leg: inhibit extensor, excite flexor
contralateral leg: inhibit flexor, excite extensor
what is the normal role of the Ib afferents?
innervate the golgi tendon organs
inhibit a m. that is overcontracting
what is the difference b/w the Ia and II afferents?
Ia innervates intrafusal bag fibers and detect the rate of change of stretch (dynamic)
II innervates intrafusal chain fibers and detect IF the m. has been stretched (static)
what do gamma motor neurons do?
innervate the ends of the m. spindle fibers (intrafusal) to maintain the Ia in an activated and prepped state
what components are present in the peripheral NS that PROMOTE nerve regeneration?
Schwann cells: important substrate for axon regrowth; secrets ECM and BL
microglial cells: clean up debris; rel IL-1, incr NGF
ECM: upreg of cell surface R and ECM glycoproteins (fibronectin and its integrin R)
what is present in the CNS that prevents nerve regrowth?
oligodendrocytes syn myelin that contains Nogo
inhibiting Nogo with a Mab (IN-1) allows n. regrowth
how is Rho related to axon regrowth?
Rho GTPase is a common downstream inhibitor of axon regrowth
what are glial scars?
physical barrier to regrowth of axons in the CNS
occur after injury in the CNS; reactive astrocytes incr expression of chondroitin sulfate proteoglycans (CSPGs)
what is the role of chondroitin sulfate proteoglycans in axon regrowth? how are they inhibited?
CSPG inhibit axon growth (glial scar)
CSPGs also upreg Rho levels
chondroitinase ABC breaks down CSPGs and facilitate regrowth
what are 4 possible therapeutic strategies that are being investigated for axon regrowth?
chondroitinase ABC
Nogo Ig: blocks Nogo activity
Nogo peptide: competes with Nogo for Nogo R
olfactory ensheathing cells: forms bridge to allow axon regrowth
why might you see a positive babinski sign in an infant?
infants lack myelination on their corticospinal tract and so they arent functioning normally yet-> hyperreflexia, hypertonia