Final answer:
Sodium ions entering the neuron cause depolarization and initiate the action potential, allowing current to flow to adjacent sections of the axon. This change in charge is necessary for the transmission of neural signals.
Step-by-step explanation:
When sodium ions enter the neuron, current flows to adjacent sections of the axon. The first voltage-gated ion channels to open are those that allow sodium ions (Na+) to enter the cell.
This influx of sodium ions increases the positive charge inside the neuron compared to the outside, leading to depolarization of the membrane and initiating the action potential. The action potential subsequently travels down the axon, enabling rapid communication between neurons.
The flow of ions into the neuron greatly affects the relative membrane potential. Entry of positively charged sodium ions reduces the resting membrane potential, making the inside of the neuron less negative compared to the outside, in a process known as depolarization. This flow of ions is critical for the propagation of the electrical signal along the axon and for neurotransmission at synapses.