Question:
Which receptors are blocked in myasthenia gravis?
Which receptors are blocked in myasthenia gravis?
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Autoantibodies destroy postsynaptic nicotinic acetylcholine receptors.
Updated On: Jun 24, 2026
- Acetylcholine (Ach) receptors
- Ca2+ receptors
- Na+ receptors
- Opioid receptors
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The Correct Option is A
Solution and Explanation
Step 1: Myasthenia gravis is an autoimmune disorder of the neuromuscular junction. The body produces antibodies that target a specific component of the postsynaptic membrane.
Step 2: These autoantibodies are directed against the nicotinic acetylcholine receptors (AChRs) on the muscle end plate, blocking and destroying them and flattening the post-junctional folds. With fewer functional acetylcholine receptors, the junction cannot reliably transmit the nerve signal to the muscle, producing fluctuating weakness and fatigability that worsen with use. So the receptors blocked are the acetylcholine receptors.
Step 3: Why the others are wrong. Calcium-channel antibodies (against presynaptic voltage-gated calcium channels) characterise Lambert-Eaton myasthenic syndrome, not myasthenia gravis. Sodium and opioid receptors are not the autoimmune targets in this disease. Treatment with anticholinesterases such as neostigmine improves strength by raising synaptic acetylcholine.
Step 2: These autoantibodies are directed against the nicotinic acetylcholine receptors (AChRs) on the muscle end plate, blocking and destroying them and flattening the post-junctional folds. With fewer functional acetylcholine receptors, the junction cannot reliably transmit the nerve signal to the muscle, producing fluctuating weakness and fatigability that worsen with use. So the receptors blocked are the acetylcholine receptors.
Step 3: Why the others are wrong. Calcium-channel antibodies (against presynaptic voltage-gated calcium channels) characterise Lambert-Eaton myasthenic syndrome, not myasthenia gravis. Sodium and opioid receptors are not the autoimmune targets in this disease. Treatment with anticholinesterases such as neostigmine improves strength by raising synaptic acetylcholine.
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