Final answer:
An action potential is the pulse of voltage inside a nerve cell. The process involves depolarization, peak action potential, repolarization, hyperpolarization, and return to resting potential. Active transport maintains ion concentration differences.
Step-by-step explanation:
An action potential is the pulse of voltage inside a nerve cell. It is caused by movements of ions across the cell membrane. The events that occur during an action potential can be divided into several steps:
- Depolarization: A stimulus makes the membrane permeable to Na+ ions, causing the membrane voltage to increase.
- Peak Action Potential: K+ channels open and K+ ions start to leave the cell, while Na+ channels close.
- Repolarization: The membrane voltage returns to a negative value as K+ ions continue to leave the cell.
- Hyperpolarization: The membrane becomes briefly more negative than the resting potential.
- Resting Potential: The membrane voltage returns to the resting value.
Throughout these steps, the concentration differences of ions are maintained through active transport, allowing the cell to fire multiple action potentials in rapid succession without depleting these differences significantly.