Final answer:
Hyperpolarization is the increase in membrane potential making the inside of the cell more negative than the resting state, often after a neuron has fired an action potential. The resting membrane potential of around -70 mV is maintained by the sodium-potassium pump and must be re-established for further action potentials to occur.
Step-by-step explanation:
The change in membrane potential moving from an extreme depolarized state and becoming extremely negative, more negative than the resting potential, is known as hyperpolarization. This occurs during the undershoot phase of the action potential. When a neuron is stimulated, it first experiences depolarization where sodium ions (Na+) rush into the cell due to higher concentrations outside the cell, this reduces the charge difference making the inside of the cell less negative. The overshoot of positive potential then triggers the opening of potassium channels, leading to an outflow of potassium ions (K+) restoring the negative charge inside. If excessive potassium leaves, it can result in the membrane potential becoming even more negative than during the resting state
Neurons at rest typically exhibit a resting membrane potential of approximately -70 mV, maintained by the sodium-potassium pump which actively transports ions against their concentration gradients. During hyperpolarization, the membrane potential can dip to values even lower than the resting state. The neuron must then return to the resting potential before it can fire an action potential again, which requires energy and is vital for proper neural function.