During an action potential, the loss of potassium ions (\(K^+\)) from the cell results in:

• A. Repolarization of the membrane
• B. Initiation of the action potential
• C. Depolarization of the membrane
• D. Release of neurotransmitters

Answer: (A)

Verified step by step guidance

1. Understand the concept of an action potential: An action potential is a rapid change in the membrane potential of a neuron, which occurs in response to a stimulus. It involves depolarization, repolarization, and a return to the resting state.
2. Recall the role of potassium ions (\(K^+\)) in repolarization: During repolarization, voltage-gated potassium channels open, allowing \(K^+\) ions to flow out of the cell. This movement restores the negative charge inside the cell membrane.
3. Differentiate between depolarization and repolarization: Depolarization occurs when sodium ions (\(Na^+\)) enter the cell, making the inside of the membrane more positive. Repolarization, on the other hand, occurs when \(K^+\) ions leave the cell, restoring the negative membrane potential.
4. Connect the loss of \(K^+\) ions to repolarization: The outward flow of \(K^+\) ions is the key event that drives repolarization, as it helps the membrane potential return to its resting state after depolarization.
5. Eliminate incorrect options: The loss of \(K^+\) ions does not initiate the action potential (this is caused by \(Na^+\) influx), nor does it cause depolarization (this is also due to \(Na^+\) influx). It is not directly responsible for neurotransmitter release, which occurs at the synapse. Therefore, the correct answer is repolarization of the membrane.