The depolarization phase begins when a stimulus causes the membrane potential of a cell to reach a critical level known as the threshold. This electrochemical event is the foundational mechanism behind all neural communication, muscle contraction, and sensory perception. Without depolarization, the involved network of signals that governs the human body would cease to function. To fully understand this vital process, Explore the state of the cell before depolarization occurs, the precise trigger that initiates it, and the rapid cascade of events that follow — this one isn't optional.
The Baseline: Understanding the Resting Membrane Potential
Before the depolarization phase can begin, a cell must be in its resting state. Neurons and muscle cells maintain a resting membrane potential, which is typically around -70 millivolts (mV). This negative charge is maintained by the
