The depolarization phase of an action potential is primarily caused by opening of which channels?

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Multiple Choice

The depolarization phase of an action potential is primarily caused by opening of which channels?

Explanation:
Depolarization during an action potential is driven by the rapid opening of voltage-gated sodium channels. When the membrane reaches threshold, these channels open quickly and let Na+ rush into the cell, carrying positive charge inward and lifting the membrane potential toward positive values. Leaky channels set the baseline permeability but don’t produce the rapid upstroke. Ligand-gated Na+ channels respond to neurotransmitters and generate graded, synaptic potentials rather than the fast, all-or-nothing spike. Voltage-gated K+ channels open later to let K+ exit and repolarize the membrane.

Depolarization during an action potential is driven by the rapid opening of voltage-gated sodium channels. When the membrane reaches threshold, these channels open quickly and let Na+ rush into the cell, carrying positive charge inward and lifting the membrane potential toward positive values. Leaky channels set the baseline permeability but don’t produce the rapid upstroke. Ligand-gated Na+ channels respond to neurotransmitters and generate graded, synaptic potentials rather than the fast, all-or-nothing spike. Voltage-gated K+ channels open later to let K+ exit and repolarize the membrane.

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