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26 Cards in this Set
- Front
- Back
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Type 1 vs Type 2 Meat
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Type 1: red meat; slow twitch; stustained action, more mitochondria, oxidative phosphorylation
Type 2: white meat; fast twitch, glycolytic enzymes, fewer mitochondria, GLYCOLYSIS |
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What is the hallmark feature of muscle atrophy?
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Variability in muscle fiber size
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What is grouped fiber atrophy?
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Loss of mosaicism bc:
motor neuron innvervating muscle fibers die and surrounding neurons (of opposite type presumably) innervate those fascicles |
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What is a dystrophy?
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Progressive destruction of muscle after birth
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What is a congenital myopathy?
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Present at work; weakness is fixed and non-progressive
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Duchenne MD:
Sex Age of Onset Hallmark feature |
Affects boys (x-linked)
Onset at age 5-6 FEATURE: Pseudohypertrophy of calves (it's fat, not mm) |
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Dystrophin gene
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Duchenne MD
Becker MD |
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Elevated CPK
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Seen in Duchenne MD at onset; decreases as run out of muscle to destroy
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Gower's sign
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Duchenne MD--child can't get up on legs without getting on all four limbs and pressing up from thighs
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Becker MD:
Age of onset Clinical course |
x-linked (boys)
Due to dystrophin mutation Onset in 2-16 years Milder clinical course |
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Dystrophin activity in Duchenne vs Becker
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Duchenne: no dystrophin activity
Becker: some dystrophin activity |
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Limb-Girdle Muscular Dystrophy:
Presentation |
Proximal muscle weakness--trouble combing hair, trouble reaching for things
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Mutation in sarcoglycans, caveolin.
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i.e., mutations in cytoskeletal proteins; Limb-Girdle Muscular Dysrophy
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Distal weakness--in hands, feet.
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Myotonic MD
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Myotonic Muscular Dystrophy:
Presentation |
Myotonia (can't relax muscles)
Hatchet-like face (atrophy of masseters) Frontal baldness |
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Selective atrophy of type II fibers.
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Steroid use
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Selective atrophy of type I fibers.
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Myotonic MD
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Brain damage in addition to muscle disease.
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Mitochondrial myopathies
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Dermatomyositis vs Polymyositis:
Cells involved Fiber damage type Location of inflammation Antibody role |
Dermatomyositis:
B cells/CD4+ Ischemic Fiber Damage Inflammation around BVs Membrane-attack from Ab Polymyositis: CD8+ T-cells Direct fiber damage inflammation around fibers Not Ab mediated |
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Perifascicular atrophy
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Dermatomyositis
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A skin rash can be seen in this muscle disorder.
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Dermatomyositis
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Distal and proximal weakness in elderly men.
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Inclusion body myositis
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Myasthenia gravis:
Pathophys |
Ab's x ACh receptor
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Increasing weakness with repetitive action.
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Myasthenia gravis (can't look up at ceiling for long)
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Lambert-Eaton Myasthenic Syndrome:
Patophys |
Abs x presynaptic Ca2+ channels
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Increasing strength with repetitive action.
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Lambert-Eaton myasthenic syndrome
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