Mastering A&P Neurophysiology Practice Test

The opening of sodium channels in the axon membrane leads to depolarization because it allows sodium ions (Na+) to flow into the neuron. This influx of positively charged sodium ions changes the membrane potential, making the inside of the cell more positive relative to the outside.

During depolarization, the resting membrane potential, which is typically around -70 mV, moves closer to zero and can even reach positive values as more sodium ions enter. This change is a critical step in the generation of action potentials, which are essential for the propagation of signals along the axon. Once the threshold for action potential is reached, it triggers additional sodium channels to open, leading to a rapid rise in membrane potential.

In summary, the opening of sodium channels is a key event in neuronal signaling that results in depolarization, setting the stage for further electrical activity within the neuron.