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How do Na⁺ ions enter a neuron when an action potential is initiated?

1) the Na⁺/K⁺-ATPase
2) a gated Na⁺ pump
3) a voltage-gated Na⁺ channel
4) the ligand-gated Na⁺ channel
5) a voltage-gated Na⁺ facilitated transporter

User Geekzeus
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1 Answer

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Final answer:

Na⁺ ions enter a neuron through voltage-gated Na⁺ channels when an action potential is initiated, initiating the depolarization process of the neuron; this influx of Na⁺ ions is critical for the propagation of the action potential. Option number 3 is correct.

Step-by-step explanation:

Na⁺ ions enter a neuron during the initiation of an action potential primarily through voltage-gated Na⁺ channels. These channels have two gates—an activation gate and an inactivation gate. The activation gate opens when the membrane potential reaches approximately -55 mV, allowing Na⁺ to rush into the neuron, causing depolarization. Following a brief period, the inactivation gate closes to stop the influx of Na⁺, aiding in repolarization as K⁺ channels open and potassium ions exit the cell.

After the action potential has passed, the Na⁺/K⁺-ATPase helps to restore the resting membrane potential by pumping Na⁺ out of the cell and K⁺ back in, although this pump is not directly involved in the action potential initiation.

User KodeWarrior
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