Resting Potential

[anyusernamenottaken]

question from EK book:
If a neuronal memb were to become suddenly impermeable to K+ but were retain an active NA+K+ ATPase, the neuron's resting potential would:

Answer: Become more positive because K+ ions concentration would increase inside the neuron.


how would K+ become concentration increase inside the cell if the cell became impermeable to K. if this were the case shouldn't the resting potential become more - since Na is still being pumped out the cell while K can no longer be pumped into the cell?

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[NextStepTutor_1]

Hi @anyusernamenottaken -

Excellent question! The idea here is that there are two main mechanisms you need to know: (1) the Na+/K+ pump, which pumps Na+ out and K+ in, and (2) leak channels that allow Na+ and K+ to diffuse down their gradients. The question is asking about a situation in which mechanism (2) is broken but mechanism (1) still works -- so K+ can enter the cell b/c that's inherent to how the Na+/K+ pump works, but K+ can't diffuse through leak channels to leave the cell.

Hope this helps clarify things!