객관식
Which factor primarily determines whether a neuron will generate an action potential?
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45. Nervous System
Neurons and Action Potentials
객관식
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
검증된 단계별 안내1
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.
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.
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.
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.
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.
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