Moderate

During the propagation of a nerve impulse the action potential results from the movement of _

Correct answer: B. Na+ ions from extracellular fluid to intracellular fluid

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

Explanation

An action potential is a 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 because 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.

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About Coordination and Control

Coordination depends on receptors, neurons, synapses and nerve impulses, with reflex actions traced through the reflex arc and the roles of major brain regions. Chemical coordination covers endocrine glands and hormones, including how hormones regulate growth, metabolism, reproduction and internal balance, unlike rapid nervous control.

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