At the height of the action potential,
A) the interstitial fluid is more negatively charged than the cytoplasmic fluid.
B) the interstitial fluid is less negatively charged than the cytoplasmic fluid.
C) the interstitial fluid and the cytoplasmic fluid have the same charge.
D) all sodium and potassium ions rush out of the neuron.
E) both a and d occur.

Question

Quizplus · Accepted Answer

At the height of the action potential, the inside of the neuron becomes positively charged due to the influx of sodium ions. This, in turn, causes the interstitial fluid (the fluid outside of the neuron) to become more negatively charged, creating an electrical gradient. Therefore, choice A is correct. Choice D is incorrect because while sodium ions do rush into the neuron at the beginning of the action potential, potassium ions rush out of the neuron later in the process.

At the Height of the Action Potential