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6 Cards in this Set
- Front
- Back
describe the normal process of neuromuscular transmission
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1. exocytosis - release of 1 quanta
2. depolarization of the nerve terminal 3. Ca2+ release - triggers release of multiple quanta 4. release sites are directly opposite to the areas with the highest concentration of Ach 5. transmission depends on the # of Ach molecules redadily available to interact with receptors any change that reduces the probablity of Ach interaction will result in failure of neuromuscular transmission |
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What can cause myasthenia gravis, in regard to the normal neuromuscular transmission process
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1. not enough quanta release
2. too little # Ach per quanta 3. post synaptic effect of Ach 4. membrane/receptor damage 5. blocked binding sites * |
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what is the main theory behind the cause of myasthenia
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- IgG competes with Ach for attachment at the same receptor, therefore preventing Ach from binding to the receptor site
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Why is a careful Hx important in myasthenic pts
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- 5% have a thymic tumor
- 5% have Graves diseaasw - thymoma - need chest X-ray |
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what are some Dx tests you can do to confirm myasthenia gravis as Dx
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- sleep test
- ice test - tensilon or prostignin - EMG |
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describe the signs and symptoms of myasthenia
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CPR - HOPE - PMF
Cogan's lid twitch - look down, then up - lid elevates too much then eye "flutters down" Pupil fatigue Retraction of lid (with thyroid) Hopping of lid Orbicularis oculi involved Ptosis Enhancement of Ptosis Paradoxial reversal of ptosis Myasthenic crisis Facial snarl |