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Old 01-22-2013
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Default AP( physio)

Whats the mechanism of Hyperkalemia producing Muscle weakness?

1.resting membrane potential hyperpolarized
2. K equilibrium potential Hyperpolarized
3.Na equilibrium Potential Hyperpolarized
4.K channels opened by Depolarization
5.Na channels closed by depolarization.
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Old 01-23-2013
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i think option 4 is rite answer
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Old 01-23-2013
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too much K+ outside the cell=K+ is gonna wanna move inside the cell because normally the "resting membrane potential" is almost equal to that of K+, so K+ ends up moving inside in order to reach that equilibrium. Now this makes the cell more positive inside, which means that it will depolarize easier/faster because the threshold is lowered. If this imbalance happens long enough, Na channels inactivate and remain that way until repolarization occurs and this produces muscle weakness.

therefore, the answer is 5: Na channels closed by depolarization

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Old 01-23-2013
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thanks for a beautiful fluidic,logical explanation.
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Old 01-24-2013
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That is a very comprehensive explanation about the topic. I really helped me in my thesis
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Old 01-24-2013
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Ans: 5
As said by Sarah M, elevated serum k cause depolarization of k equilibrium potential, hence depolarization of resting memb potential in skeletal muscle. Sustained depolarization cause inactivation gates on na channels to close and prevent next action potential in muscle-- weakness.
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