Final answer:
Hyperpolarization occurs when the cell membrane's potential becomes more negative than its resting state due to outward K+ movement or inward Cl- movement.
Step-by-step explanation:
Hyperpolarization in Nerve Cells
When discussing membrane potentials in nerve cells, a key concept is hyperpolarization. This occurs when the potential difference across the cell membrane becomes more negative than the resting potential, typically around -70 mV in neurons. The resting potential is maintained due to a separation of charge across the cell membrane, creating a voltage that has significant effects on the cell's structure and permeability.
When voltage-gated potassium channels open, K+ ions, driven by a concentration gradient, exit the cell, taking positive charges with them and moving the membrane potential towards its resting state in a phase called repolarization. If potassium channels remain open longer or additional channels open, allowing more K+ to leave the cell, it can result in the membrane potential becoming more negative than -70 mV, leading to hyperpolarization. Hyperpolarization can also be the result of Cl- ions entering the cell, as incoming negative charges also make the interior more negative relative to the outside.