Question

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

• A. $K^{+}$ ions from intracellular fluid to extracellular fluid
• B. $N{a}^{+}$ ions from extracellular fluid to intracellular fluid
• C. $K^{+}$ ions from extracellular fluid to intracellular fluid
• D. $N{a}^{+}$ ions from intracellular fluid to extracellular fluid

Answer 1

The correct option is B $N{a}^{+}$ ions from extracellular fluid to intracellular fluid

Nerve impulses are initiated by incoming chemical stimuli or excitatory signals which decrease the membrane potential and depolarize the membrane. With depolarization of the membrane, there is an increase in its permeability to sodium ions. The positively charged sodium ions rush inwards into the interior of the cell while potassium ions rush outwards to the exterior of the cell. This spike of electrical activity is called the action potential and generates the nerve impulse.

So, the correct answer is '$N{a}^{+}$ ions from extracellular fluid to intracellular fluid'.