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Retired NBME 22 Answers

nbme22/Block 4/Question#23 (reveal difficulty score)
A 57-year-old woman comes to the office ...
Autoimmune downregulation of Ca2+ channels of the presynaptic terminal ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–
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submitted by โˆ—welpdedelp(270)
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This is Lambert-Eaton, which improves with movement as compared to Myesthenia gracias whichh worsens with movement

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sbryant6  Lambert-Eaton is typically associated with Small Cell Lung Cancer. Since there was no mentino of that, I was thrown off. Such is the difference between UWorld and NBME I guess. +3
makinallkindzofgainz  I'm laughing about Myasthenia "gracias" lmao +20



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submitted by โˆ—meryen13(48)
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how to remember its lamber eaton and not MG: it doesn't matter how much you move your muscle the ach receptor is blocked the same amount and ach release will by repetitive movement is not gonna change the number of available receptors in Lambert the more you move the muscle the more calcium is released to fuse the vesicle with the plasma membrane and if finally you get enough concentration of calcium in the cell, you will merge the vesicle with the plasma membrane and enough a normal amount of ach is in the synapse.

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submitted by โˆ—trichotillomaniac(121)
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antibodies form against the presynaptive Ca2+ channels at the NMJ-most commonly seen in patients with small cell lung cancer

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submitted by โˆ—trichotillomaniac(121)
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antibodies form against the presynaptive Ca2+ channels at the NMJ-most commonly seen in patients with small cell lung cancer

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submitted by โˆ—tekkenman101(19)
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This question is pretty bad because down regulation of calcium channels in PREsynaptic neurons would result in LESS ACh release onto the motor-end plate, which would cause down signaling and impaired excitation-extraction coupling of muscle. This is because that mechanism needs depolarization and release of calcium to work.

I guess you just can't overthink it lol.

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skonys  That's why they include "muscle strength intially improves upon repetitive manual motor testing." They love testing MG vs LES in the context of which get's better or worst with exercise. Repetitive motor use eventually releases enough calcium into the presynaptic nerve terminal to stimulate the fusion of a NT vesicle and causing the contraction. Not every Ca+ ch is blocked, just some. +



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