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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?
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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 |
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what does the babinski sign suggest in the role of the corticospinal tract?
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that it may play a role in downregulating reflexes
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what is the flexion/cross extension reflex?
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R foot steps on pin (activated by cutaneous nociceptors)
ipsilateral leg: inhibit extensor, excite flexor contralateral leg: inhibit flexor, excite extensor |
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what is the normal role of the Ib afferents?
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innervate the golgi tendon organs
INVERSE MYOTACTIC REFLEX inhibit a m. that is overcontracting |
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what is the difference b/w the Ia and II afferents?
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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) |
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what do gamma motor neurons do?
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innervate the ends of the m. spindle fibers (intrafusal) to maintain the Ia in an activated and prepped state
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what components are present in the peripheral NS that PROMOTE nerve regeneration?
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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) |
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what is present in the CNS that prevents nerve regrowth?
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oligodendrocytes syn myelin that contains Nogo
inhibiting Nogo with a Mab (IN-1) allows n. regrowth |
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how is Rho related to axon regrowth?
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Rho GTPase is a common downstream inhibitor of axon regrowth
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what are glial scars?
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physical barrier to regrowth of axons in the CNS
occur after injury in the CNS; reactive astrocytes incr expression of chondroitin sulfate proteoglycans (CSPGs) |
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what is the role of chondroitin sulfate proteoglycans in axon regrowth? how are they inhibited?
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CSPG inhibit axon growth (glial scar)
CSPGs also upreg Rho levels chondroitinase ABC breaks down CSPGs and facilitate regrowth |
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what are 4 possible therapeutic strategies that are being investigated for axon regrowth?
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chondroitinase ABC
Nogo Ig: blocks Nogo activity Nogo peptide: competes with Nogo for Nogo R olfactory ensheathing cells: forms bridge to allow axon regrowth |
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why might you see a positive babinski sign in an infant?
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infants lack myelination on their corticospinal tract and so they arent functioning normally yet-> hyperreflexia, hypertonia
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