Hyperkalemia and the resting membrane potential
How does a large rise in extracellular K+ affect a neuron's resting membrane potential?
Answer B: explanation for every choice
A
Hyperpolarization would follow a drop in extracellular K+.
B
Correct. A smaller K+ gradient lowers the K+ equilibrium potential, which mainly sets the resting potential, so the membrane depolarizes.
C
The pump cannot override a large change in the extracellular concentration.
D
The membrane depolarizes but does not reverse to a positive value at rest.
TakeawayResting potential tracks the K+ gradient. More K+ outside → depolarization.
Equation usedNernst equation
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