What is the voltage range at which voltage-gated potassium channels are shut?

Voltage-gated potassium channels primarily open and close in response to changes in membrane potential, which is critical for the repolarization phase of action potentials in neurons and muscle cells. These channels are typically closed at resting membrane potential, which is around -70mV. As the cell depolarizes during an action potential, the membrane potential becomes more positive, reaching levels that can exceed +30mV.

The correct voltage range at which these channels are shut is from around -90mV, where they effectively close before depolarization occurs, to +20mV, which indicates that they are starting to reopen after becoming activated by the depolarization. This range reflects the physiological behavior of voltage-gated potassium channels: they close as the cell becomes depolarized and begin to open again as repolarization starts, thus allowing potassium to flow out of the cell to restore resting potential.

Understanding this voltage range is crucial for grasping how action potentials are propagated and how cells maintain their resting membrane potentials.