What is the primary action of sodium ions during the depolarization phase?

During the depolarization phase of an action potential, sodium ions play a crucial role in rapidly changing the membrane potential of a neuron. When a stimulus reaches a neuron, voltage-gated sodium channels open, allowing sodium ions to enter the neuron. This influx of positively charged sodium ions increases the overall positive charge inside the neuron, making the interior of the cell less negative compared to the outside. This change in membrane potential is essential for the propagation of the action potential along the axon.

This process is vital for neuronal communication, as it leads to the generation and transmission of electrical signals. The rapid depolarization, driven by sodium ion entry, is a fundamental step in neuronal signaling, enabling information to travel within the nervous system.