During depolarization, which ions rush into the neuron?

During depolarization, the primary event that occurs is the influx of sodium ions into the neuron. This process is crucial for the generation and propagation of an action potential, which is the electrical signal that travels along the neuron.

When a neuron is stimulated, voltage-gated sodium channels in the neuron's membrane open in response to a change in voltage. This results in a rapid and significant increase in the permeability of the membrane to sodium ions. Since there is a higher concentration of sodium ions outside the neuron compared to the inside, these ions rush into the cell. This influx of positive sodium ions causes the internal charge of the neuron to become more positive, which is referred to as depolarization.

The subsequent events following depolarization include the opening of potassium channels, but during the initial depolarization phase, it is specifically the sodium ions that are responsible for shifting the membrane potential to a more positive value. This is a fundamental concept in understanding how neurons communicate and transmit signals.