Movement of Sodium During Action Potential

[CTAATGT]

I know during an AP, sodium moves into the axon, down its concentration gradient, via facilitated diffusion. But during the AP, does the Na+/K+ Pump continue its work (pumping ions against their gradients)? If the pump does continue its work, then is it correct to say that during an AP, Sodium moves in via facilitated diffusion AND out via active transport?

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[boothorp]

I'm pretty sure the Na/K pump is always working.

 

[ThirdEye]

I know during an AP, sodium moves into the axon, down its concentration gradient, via facilitated diffusion. But during the AP, does the Na+/K+ Pump continue its work (pumping ions against their gradients)? If the pump does continue its work, then is it correct to say that during an AP, Sodium moves in via facilitated diffusion AND out via active transport?

It's correct to say that but for the purposes of the MCAT you shouldn't account for ATPase activity unless there's something specificly pointing it out in the passage/question. Besides, the pump is very insignificant compared to the voltage gated channels.

 

[inaccensa]

It's correct to say that but for the purposes of the MCAT you shouldn't account for ATPase activity unless there's something specificly pointing it out in the passage/question. Besides, the pump is very insignificant compared to the voltage gated channels.

Since there is a potential difference, I'm guessing that there must be electric field V= Ed. What will be the distance? is it the width that the phospholipid bilayer spans?

 

[Charles_Carmichael]

Since there is a potential difference, I'm guessing that there must be electric field V= Ed. What will be the distance? is it the width that the phospholipid bilayer spans?

Yes, because the charges line up along the inner and outer walls of the membrane.

The electrogenic contribution of the Na+/K+ pump is minimal compared to voltage gated channels, leak channels, etc.

 

[inaccensa]

Yes, because the charges line up along the inner and outer walls of the membrane.

The electrogenic contribution of the Na+/K+ pump is minimal compared to voltage gated channels, leak channels, etc.

What are you agreeing to? To the presence of voltage or the distance? What do you mean by the electrogenic contribution?

 

[Charles_Carmichael]

What are you agreeing to? To the presence of voltage or the distance? What do you mean by the electrogenic contribution?

I said yes to your question regarding the distance between the charges being equal to the width of the membrane.

Electrogenic contribution = how much the pump contributes to the membrane potential.