Neuronal Action Potential and Ionic Channels Quiz

What is the state of voltage-gated sodium channels at rest?

What contributes to the depolarization phase of the action potential?

What triggers the opening of more voltage-gated sodium channels?

What is the main contribution to the repolarization phase?

What restores the negative charge inside the neuron during repolarization?

What is the main factor contributing to the depolarization phase of the action potential?

What triggers the opening of more voltage-gated sodium channels during the action potential?

What causes the repolarization phase of the action potential?

What is the state of voltage-gated sodium channels at rest?

What is the main contribution to maintaining the resting membrane potential?

Voltage-Gated Sodium Channels at Rest

At rest, voltage-gated sodium channels are closed and have a low permeability to sodium ions.
Resting membrane potential is typically around -70 mV, maintained by non-gated potassium channels and the sodium-potassium pump.

Depolarization Phase of Action Potential

Depolarization occurs when the membrane potential becomes less negative, moving towards zero.
The main contribution to depolarization is the influx of sodium ions through opened voltage-gated sodium channels.

Trigger for Opening More Sodium Channels

The initial depolarization caused by a stimulus leads to the opening of more voltage-gated sodium channels.
This creates a positive feedback loop, allowing more sodium to flow into the neuron, further depolarizing the membrane.

Repolarization Phase

The repolarization phase is characterized by the closure of sodium channels and the opening of voltage-gated potassium channels.
Potassium ions move out of the neuron, restoring the negative charge inside.

Restoration During Repolarization

The main factor restoring negative charge during repolarization is the efflux of potassium ions, which counteracts the earlier sodium influx.

Maintaining Resting Membrane Potential

The sodium-potassium pump plays a critical role in maintaining the resting membrane potential by actively transporting three sodium ions out and two potassium ions into the cell.

Test your knowledge of neuronal action potential and ionic channels with this quiz. Learn about the changes in ionic channels that underlie the action potential, including the resting state and depolarization phase of a neuron.