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100 Cards in this Set
- Front
- Back
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What encloses muscle?
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connective tissue called epimysium
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What divides fascicles of muscle fibers?
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perimysium
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What surrounds individual muscle fibers?
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endomysium
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What is a motor unit?
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lower motor neuron and muscle fibers it innervates
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What does ATPase do?
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distinguishes muscle fiber types
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What does NADH-tetrazolium reductase do?
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reflects distribution of sarcoplasmic reticulum and mitochondria, recognizing target fibers
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What do you use myophosphorylase for?
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glycogen storage diseases
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What do you use PAS staining for?
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glycogen storage diseases
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What are Type I fibers?
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slow twitch, white
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What do Type I fibers do?
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sustained contraction, slower, more prolonged contractions
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What are Type II fibers?
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white, fast twitch
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What do Type II fibers do?
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quick, short contractions
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What identifies Type II fibers?
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more enzymes for anaerobic glycolysis, stain dark with ATPase
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What are the earliest changes of denervation?
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appearance of small fibers compressed into angular shapes by surrounding normal fibers
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What happens in acute progressive neuropathy?
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many adjacent nerve units may be lost, group atrophy, type grouping
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What is type grouping?
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innervation of one type of cells is lost, only one group of cells left, lose checkerboard pattern
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How do you stain for target fibers?
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NADH tetrazolium reductase as fibers with central pallor and darker, more condensed zone
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What are target fibers?
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sign of denervation
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What is amyotrophic lateral sclerosis?
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degneration of corticospinal tracts and anterior horn cells
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How does amyloid lateral sclerosis present?
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progressive paralysis with spasticity and hyperactive tendon reflexes
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What is the prognosis of amyotrophic lateral sclerosis?
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death due to aspiration penumonia in 2-6 years
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How does amyotrophic lateral sclerosis develop?
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sensation and muscle unaffected, begins in late middle age
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What do you see on biopsy of amyotrophic lateral sclerosis?
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chronic neuropathy, small angular fibers, fiber type grouping, large group atrophy
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What is infantile spinal muscular atrophy?
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degenerative disease of anterior horn cells
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What causes infantile spinal muscular atrophy?
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genetic, autosomal recessive
defect in apoptosis, continues after birth |
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What is Werdnig-Hoffman disease?
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infantile spinal muscular atrophy I
congenital hypotonia, progressive, death within first few years of life |
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What is Kugelberg-Welander disease?
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infantile spinal muscular atrophy II
rarer, sometimes nonprogressive form between 6-24 months |
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What do you see on muscle biopsy of type I infantile spinal muscular atrophy?
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acute neuropathy, scattered small fibers, extensive group atrophy
fibers are round due to severity |
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What do you see on muscle biopsy of type II infantile spinal muscular atrophy?
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chronic neuropathy, scattered small angular fibers, fiber type grouping
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What is poliomyelitis?
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viral disease, destruction of anterior horn cells results in paralysis
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What is the symptoms of poliomyelitis?
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fever, vomiting, diarrhea, sore throat, headache
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What is the prognosis of polio?
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death, permanent paralysis, or could have complete recovery
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What do you see on muscle biopsy of acute polio?
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little change
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What do you see on muscle biopsy of paralyzed polio fibers?
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extensive fiber atrophy with occasional persisting motor units showing compensatory hypertrophy
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What is peroneal muscular atrophy?
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progressive hereditary degenerative disease of peripheral nerves and nerve roots, just involves the distal limb muscles, begins in the feet
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What is the prognosis of peroneal muscular atrophy?
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begins in late childhood/adult, slowly progressive
also lose sensation |
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What do you see on muscle biopsy of peroneal muscular atrophy?
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chronic neuropathy, small angular fibers, type grouping, group atrophy
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What do you see on biopsy of disuse atrophy?
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only type II fibers affected, become small and angulated
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What are muscular dystrophies?
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progressive, degenerative disease of muscle, hereditary, manifest by weakness due to progressive destruction of fibers
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What do you see histologically with muscular dystrophy?
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increased connective tissue, rounded fibers, atrophic and hypertrophic
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What changes do you see in individual muscle fibers of muscular dystrophies?
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internal nuclei, fiber splitting, architectual changes, degeneration, regeneration
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What is the most common muscular dystrophy?
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Duchenne musuclar dystrophy
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What is the most severe muscular dystrophy?
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Duchenne
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How is Duchenne muscular dystrophy inherited?
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sex-linked recessive, predominantly in boys
1/3 spontaneous mutations, can occur in girls |
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What happens in Duchenne muscular dystrophy at birth?
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serum creatinine phosphokinase levels elevated
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When do you start to see symptoms of Duchenne?
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3-6 years
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What are the first symptoms of Duchenne that show up?
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weakness in pelvic, shoulder girdle muscles, calf muscles
extensive fatty infiltration |
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How does Duchenne progress?
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muscle weakness is progressive, weakness of gluteus prevents walking, can't rise from sitting position, compensatory lordosis
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What is the prognosis of Duchenne?
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confined to wheelchair by early teens, die due to pneumonia
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What does Duchenne's look like on histo section?
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extensive myopathy, extensive infiltration of muscle by fat
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What is Becker's muscular dystrophy
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milder version of Duchenne's, later onset, slower progression
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What is the genetic defect of Duchenne muscular dystrophy?
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deletion of gene on short arm of X chromosome, codes for dystrophin
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What is dystrophin?
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localized to inner surface of sarcolemma, links subsarcolemmal cytoskeleton through transmembrane complex to EC glycoprotein that binds laminin
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What happens in dystrophin-negative muscles?
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lack normal interaction between sarcolemma and ECM, increased fragility of sarcolemma, abnormal influx of Ca
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What is myotonic dystrophy?
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myotonia, progressive muscle weakness and wasting
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What is the most common adult muscular dystrophy?
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myotonic dystrophy
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What's associated with myotonic dystrophy?
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frontal balding, cataracts, endocrine dysfunction, conduction probs in heart
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What are the muscular effects of myotonic muscular dystrophy?
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general weakness, distal limb muscles affected more
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What are the histo changes of myotonic muscular dystrophy?
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myopathic changes, architectual changes in individual muscle fibers, increased internal fibers, ring fibers, sarcoplasmic masses
type I fibers have selective atrophy |
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What is the unique trait of myotonic dystrophy?
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type I fibers undergo selective atrophy
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How is myotonic dystrophy interhited?
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autosomal dominant
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What is the gene for myotonic dystrophy?
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19q13.3
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What is anticipation?
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earlier age of onset and increasing severity of symptoms in successive generations
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What genetics is anticipation related to?
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presence of unstable genomic segments, enlarges by increase in number of repeats with successive generations, correlates with severity of symptoms
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What does the gene for myotonic dystrophy code for?
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novel cAMP-dependent protein kinase, sarcolemma has altered excitability due to abnormal phosphorylation of ion channels
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What is polymyositis/dermatomyositis?
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muscle weakness and pain, muscle inflammation and degeneration
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How does polymyositis develop?
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symmetric proximal muscle weakness, insidious, progresses to moderate handicap in weeks to months
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What is dermatomyositis?
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muscle and skin lesions
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What kind of skin lesions are involved in dermatomyositis?
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erythematous rash beginning over the face and neck
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What is the prognosis of polymyositis?
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variable, can kill
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What is inclusion body myositis?
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refractory to standard tehrapy, recognized by EM with filamentous inclusions in myofibers
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What causes dermatomyositis?
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inflammatory infiltrates with lots of B cells, can be immune process against muscular microvasculature
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What causes polymyositis?
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antigen-directed cytotoxicity by cytotoxic T cells
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What do you see on biopsy of polymyositis?
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prominent muscle degeneration, phagocytosis of muscle fibers, inflammation with lymphocytes or diffuse infiltrate, prominent muscle regeneration
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What is a common histo feature of dermatomyositis?
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selective atrophy of fibers at the edge of muscle fascicles
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What is perifascicular atrophy?
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selective atrophy of fibers at the edge of muscle fascicles
associated with dermatomyositis |
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What important parasite causes muscle inflammation?
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Trichinosis
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Where do you get Trichinosis?
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encysted in pork
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How do humans get Trichinosis?
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ingest it, worm matures, migrates through host to encyst in tissues, esp skeletal muscle
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What are the symptoms of Trichinosis?
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nonspecific signs and symptoms of systemic illness: fever, fatigue, muscle tenderness, eosinophilia
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What is Type II Glycogenosis?
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most severe form, involves skeletal and cardiac muscle
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How does Type II Glycogenosis present?
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hypotonia, cardiomegaly, death in the first year of life
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What do you see on muscle biopsy of Type II Glycogenosis?
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increased glycogen, absence of acid maltase
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What do you see in Type V Glycogenosis?
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weakness, stiffness, muscle pain associated with vigorous exercise
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How do you diagnose Type V Glycogenosis?
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serum lactate fails to rise with exercise
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What is the prognosis of Type V Glycogenosis?
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normal life span
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What do you see on biopsy of Type V Glycogenosis?
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increased glycogen, negative stain for myophosphorylase
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What is myasthenia gravis?
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acquired autoimmune disease with abnormal muscle fatigability, after a few contractions, power fades, recovers with rest
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What causes myasthenia graivs?
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circulating antibodies to ACh receptor at myoneurla junction
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When does myasthenia gravis present?
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young adulthood
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How does myasthenia graivs present?
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weakness of eyes, then head and neck
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What is the prognosis of myasthenia gravis?
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course is slow and irregular, remissions of many years, death from respiratory failure
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What kind of drugs do you give for myasthenia gravis?
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anticholinesterase
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What causes myasthenia gravis?
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immune attack on ACh receptor
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What tumor is associated with myasthenia graivs?
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thymoma or thymic hyperplasia, removal can be curative
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What does myasthenia gravis look like on histo?
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can have little change, focal type II fiber atrophy, focal collections of lymphocytes
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What is rhabdomyolysis?
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dissolution of skeletal muscle fibers, release of myoglobin into circulation, can result in myoglobinuria and acute renal failure
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What happens during acute rhabdomyolysis?
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muscles are swollen, tender, weak
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What can cause rhabdomyolysis?
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mild exercise, flu, heat stroke, alcoholism
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What does rhabdomyolysis look like on path?
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active, noninflammatory myopathy, scattered necrosis, varying degeneration, regeneration, clusters of macrophages in/around muscle fibers, no lymphocytes
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