Question

For each phase of an action potential, indicate the ion channel most responsible for the membrane potential change that occurs during the phase.

Action Potential Phases Ion Channels
Depolarization phase
Repolarization phase
Hyperpolarization phase


Voltage-gated potassium channels
Chemically-gated sodium channels
Chemically-gated potassium channels
Voltage-gated sodium channels

Answer 1

Specific ion channels are responsible for the changes in membrane potential during an action potential: voltage-gated sodium channels for depolarization, and voltage-gated potassium channels for repolarization and hyperpolarization.

Step-by-step explanation:

During each phase of an action potential, specific ion channels are responsible for the changes in membrane potential that occur. These channels are integral to the process of neurotransmission within neurons.

• Depolarization phase: This phase is initiated by the opening of voltage-gated sodium channels, which allows sodium ions (Na+) to rush into the neuron. This influx of Na+ causes the membrane potential to increase.
• Repolarization phase: As the membrane potential reaches its peak, voltage-gated potassium channels open, allowing potassium ions (K+) to exit the neuron. This outflow of K+ causes the membrane potential to become more negative, moving back towards the resting potential.
• Hyperpolarization phase: This phase occurs as K+ channels remain open, allowing excessive outflow of K+, which makes the inside of the cell even more negative than during the resting state. Eventually, these channels close, and the sodium-potassium pump helps to restore the resting potential.