Sodium ions (Na⁺) play a crucial role in creating an action potential:

• At rest, the neuron is polarized (negative inside, positive outside).
• Stimulus - Na⁺ channels open - Na⁺ rushes into the neuron - depolarization.
• This sudden positive charge inside the neuron generates the action potential - nerve impulse travels along the axon.
• Later, Na⁺/K⁺ pump restores resting potential.

Tip: Na⁺ is like the “trigger” that starts the nerve signal.