OSMT (Ontario Society of Medical Technologists) Practice Exam

Depolarization occurs when there is a change in the membrane potential of a neuron, leading to the transmission of a neural impulse. This process happens when sodium channels in the neuron's membrane open, allowing sodium ions to flow into the cell. As a result, the inside of the neuron becomes less negative compared to the outside, and this shift in charge is critical for the generation and propagation of action potentials.

This means that the correct understanding of depolarization is directly tied to the active transmission of a neural signal, making it essential for the communication between neurons. The other options do not accurately capture the essence of depolarization. For example, when a neuron is at rest, it has a stable negative membrane potential, which does not involve depolarization. Simultaneously, repolarization is a phase that follows depolarization, returning the neuron to its resting state, and is not occurring together with depolarization. Lastly, threshold level refers to a specific point needed to initiate an action potential, but it is not synonymous with depolarization itself; rather, it is the trigger for depolarization to begin.