Final answer:
Hyperpolarization is caused by the slow closing of voltage-gated K+ channels, which allows excess K+ to leave the cell, making the inside more negative. This overcorrects the membrane potential, leading to hyperpolarization before the cell returns to resting potential.
Step-by-step explanation:
Hyperpolarization results from the slow closing of voltage-gated K+ channels. When an action potential occurs, there's a sequential opening and closing of voltage-gated Na+ and K+ channels. Voltage-gated Na+ channels open first, allowing Na+ ions to enter the cell, leading to depolarization. Following this, K+ channels open, and as the membrane potential starts to repolarize, the Na+ channels are inactivated. The voltage-gated K+ channels open more slowly and close slowly as well.
As the K+ channels begin to close with a delay, potassium continues to exit the cell, causing the inside of the cell to become more negative. This overcorrection results in the membrane potential dropping lower than the resting potential, which is known as the hyperpolarizing overshoot. It is this delay in closing the K+ channels that gives rise to hyperpolarization. After the channels close, the Na+/K+ transporter and non-gated channels help the membrane to return to resting potential.