Before an action potential begins, the fluid outside an axon's membrane has ________ ions; the fluid inside has ________ ions.

Question

Quizplus · Accepted Answer

Before an action potential, the fluid outside an axon's membrane has a high concentration of positively charged ions (usually sodium) and a low concentration of negatively charged ions (usually chloride). Meanwhile, the fluid inside the axon has a high concentration of negatively charged ions (usually potassium) and a low concentration of positively charged ions. This difference in ion concentrations is known as the membrane potential and is necessary for the generation of action potentials. Option C correctly identifies that the fluid outside the axon has mostly positively charged ions, while the fluid inside has mostly negatively charged ions.

Before an Action Potential Begins, the Fluid Outside an Axon's