Final answer:
Repolarization is the phase in the action potential where the neuron's membrane potential returns from a depolarized state (+30 mV) back towards the resting potential (-70 mV) and temporarily becomes more negative due to slightly delayed closing of K+ channels, a phenomenon known as hyperpolarization.
Step-by-step explanation:
The Action Potential and Repolarization
During an action potential, the membrane potential of a neuron undergoes a series of changes. Initially, it is at the resting membrane potential of approximately -70 mV. When a neuron is stimulated, the membrane potential depolarizes, reaching up to +30 mV as sodium ions (Na+) rush into the cell. This depolarization corresponds to the nerve signal's peak. Following this peak, repolarization occurs as potassium ions (K+) flow out of the cell, pulling the membrane potential back down. This repolarizing phase takes the membrane potential below -70 mV, a state known as hyperpolarization, before it eventually settles back to the resting potential.
During repolarization, the membrane potential is restored towards -70 mV. It overshoots due to the slightly delayed closing of K+ channels, causing hyperpolarization. This process is essential for nerve cells to reset and be ready for the next action potential, ensuring efficient nerve signal transmission.
The action potential process is crucial for communication within the nervous system and requires substantial cellular energy to maintain. The change in voltage during an action potential is significantly less than what we see in common batteries, but it plays a critical role in cellular communication.