Multiple Choice
Dendrites receive stimulus input from which of the following sources?
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45. Nervous System
Neurons and Action Potentials
Multiple Choice
Which of the following best characterizes depolarization, the first phase of the action potential in a neuron?
A
Efflux of K\(^+\) ions out of the cell, making the membrane potential more negative
B
Opening of voltage-gated Ca\(^{2+}\) channels, leading to neurotransmitter release
C
Rapid influx of Na\(^+\) ions into the cell, making the membrane potential more positive
D
Restoration of the resting membrane potential by the Na\(^+\)/K\(^+\) pump
Verified step by step guidance1
Step 1: Understand the concept of depolarization. Depolarization is the first phase of an action potential in a neuron, during which the membrane potential becomes less negative (more positive) compared to the resting potential.
Step 2: Recall the role of ion channels in depolarization. During this phase, voltage-gated Na\(^+\) (sodium) channels open in response to a stimulus, allowing Na\(^+\) ions to flow into the neuron.
Step 3: Analyze the effect of Na\(^+\) influx. The rapid influx of positively charged Na\(^+\) ions into the cell causes the inside of the neuron to become more positive relative to the outside, leading to depolarization.
Step 4: Eliminate incorrect options. Efflux of K\(^+\) ions out of the cell makes the membrane potential more negative, which is characteristic of repolarization, not depolarization. Opening of voltage-gated Ca\(^{2+}\) channels is associated with neurotransmitter release, not depolarization. The Na\(^+\)/K\(^+\) pump restores the resting membrane potential after the action potential, not during depolarization.
Step 5: Identify the correct characterization. The correct description of depolarization is the rapid influx of Na\(^+\) ions into the cell, making the membrane potential more positive.
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