What is hyperpolarization?

What is hyperpolarization?

• A. A state where the resting membrane potential (RMP) becomes more positive and cells are more excitable.
• B. A state where the resting membrane potential (RMP) is reset to a less positive number than normal, lengthening the polar gap and making cells less sensitive.
• C. A state where the RMP is unchanged and remains at -70 mV.
• D. A state where cells depolarize briefly during action potential.

Answer: (B)

Hyperpolarization is when the membrane potential becomes more negative than the usual resting value. Neurons typically sit at about -70 mV at rest; after an action potential, potassium channels can stay open longer, driving the inside of the cell to a more negative level (often around -80 to -90 mV). This makes the difference between the membrane potential and the threshold for firing larger, so a stronger signal is needed to trigger another action potential and the cell becomes less excitable. The phrase “less positive” captures the negative shift, and “lengthening the polar gap” refers to the increased distance to the threshold. By contrast, depolarization makes the cell more positive and more likely to fire, staying at the resting potential means no change, and depolarization during an action potential is the rise phase, not the hyperpolarization that follows.

Hyperpolarization is when the membrane potential becomes more negative than the usual resting value. Neurons typically sit at about -70 mV at rest; after an action potential, potassium channels can stay open longer, driving the inside of the cell to a more negative level (often around -80 to -90 mV). This makes the difference between the membrane potential and the threshold for firing larger, so a stronger signal is needed to trigger another action potential and the cell becomes less excitable. The phrase “less positive” captures the negative shift, and “lengthening the polar gap” refers to the increased distance to the threshold. By contrast, depolarization makes the cell more positive and more likely to fire, staying at the resting potential means no change, and depolarization during an action potential is the rise phase, not the hyperpolarization that follows.