At rusting membrane potential voltage, gated potassium ion channels are open true or false
The correct answer and explanation is:
Correct Answer: False
At the resting membrane potential, voltage-gated potassium ion channels are generally closed, not open.
The resting membrane potential is typically around –70 millivolts in neurons. This potential is primarily maintained by the sodium-potassium pump and the leak channels, especially potassium leak channels that allow a small amount of K⁺ to diffuse out of the cell. These leak channels are not the same as voltage-gated potassium channels.
Voltage-gated potassium channels are specialized proteins in the cell membrane that respond to changes in the membrane’s voltage. They remain closed at the resting membrane potential and only open when the membrane becomes sufficiently depolarized, typically during an action potential. When a neuron is stimulated and the membrane potential rises toward a threshold (around –55 millivolts), voltage-gated sodium channels open first, allowing sodium ions to rush in and depolarize the membrane further. Shortly after this depolarization, voltage-gated potassium channels open.
The opening of voltage-gated potassium channels allows K⁺ ions to move out of the cell. This outward movement of positively charged ions repolarizes the membrane, bringing the potential back toward the resting state after the depolarization caused by sodium influx. In fact, the delayed opening of these potassium channels is crucial for the repolarization and the subsequent hyperpolarization phase of the action potential.
Therefore, voltage-gated potassium channels are not open at rest. Their activation is part of a tightly regulated response to electrical changes in the membrane, specifically designed to reset the membrane potential after a nerve impulse has passed. The resting potential is mainly maintained by passive ion movement through leak channels and active transport by pumps, not by the activity of voltage-gated channels.