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Which statement is true regarding the role of potassium ions during depolarization?

  1. Potassium ions move into the cell during depolarization

  2. Potassium ions are not involved in depolarization

  3. Potassium ions diffuse out of the cell

  4. Potassium ions are the primary cause of hyperpolarization

The correct answer is: Potassium ions diffuse out of the cell

During depolarization, the primary focus is on changes in membrane potential that lead to an excitatory response in neurons and muscle cells. The correct statement regarding the role of potassium ions is that they diffuse out of the cell. Initially, during depolarization, there is a rapid influx of sodium ions that causes the potential inside the cell to become more positive. However, after reaching a certain threshold and during the repolarization phase that follows depolarization, potassium ions move out of the cell. This movement of potassium ions out of the cell helps restore the resting membrane potential after the depolarization phase by counteracting the positive charge that has entered. The diffusion of potassium ions out of the cell is critical for returning the cell to its polarized state, demonstrating their significant role in membrane potential dynamics. While potassium ions do play roles in different phases of action potentials, their outward movement is crucial for the repolarization that follows depolarization. Therefore, this statement accurately reflects the physiological process involved in action potential propagation in excitable tissues.