Question

During the propagation of nerve impulse, the action potential results from the movement of

• A. K⁺ ions from intracellular fluid to extracellular fluid
• B. Na⁺ions from extracellular fluid into intracellular fluid
• C. K⁺ ions from extracellular fluid to intracellular fluid
• D. Na⁺ ions from intracellular fluid to extracellular fluid

Answer 1

Answer: (B)

Action potential is the change in electrical potential that occurs across a plasma membrane during the passage of a nerve impulse. As an impulse travels in a wavelike manner along the axon of a nerve, it causes a localized and transient switch in electric potential across the membrane from - 60 mV (millivolts; the resting potential) to + 45 mV. It is due to the fact that the sodium channels open and the potassium channels remain closed. As a result, sodium channels permit the influx of Na+ by diffusion from extracellular fluid to intracellular fluid.