Nerve and muscle: action potential, synapse, neuromuscular junction
Physiology · MBBS
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Study notes
A patient has drooping eyelids and weakness that worsens with activity, improving with rest. This is myasthenia gravis — antibodies destroy acetylcholine receptors at the neuromuscular junction. Each nerve impulse releases normal ACh, but fewer receptors catch it, so repeated use exhausts the muscle (fatigable weakness). Rest restores strength temporarily. Drugs that boost ACh (anticholinesterases) improve symptoms — the basis of the diagnostic edrophonium test.
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