Final answer:
An action potential is generated through a series of steps, starting with a stimulus that depolarizes the target cell towards the threshold potential. Sodium (Na+) channels open and the membrane depolarizes at the threshold. Potassium (K+) channels then open, causing K+ ions to leave the cell and hyperpolarizing the membrane. The K+ channels eventually close, and the Na+/K+ transporter restores the resting potential.
Step-by-step explanation:
An action potential is generated through a series of steps. First, there is a stimulus that causes the target cell to depolarize towards the threshold potential. If the threshold of excitation is reached, sodium (Na+) channels open and the membrane depolarizes. At the peak of the action potential, potassium (K+) channels open and K+ ions begin to leave the cell, while Na+ channels close. The membrane then becomes hyperpolarized as K+ ions continue to leave the cell, and this hyperpolarized membrane cannot fire. Finally, the K+ channels close and the Na+/K+ transporter restores the resting potential.