Correction to Sodium and Potassium Pump Video

[bs0u31c3]

Without you use students would be hopeless. I dont know why I pay ridiculous tuition fees when my professors dont teach me anything. I learn more at home with youtube and Khan. May God bless you.

[cwaddle]

very good

[jeanpeup]

Thanks Sal

Thanks Stephen

Very usefull

[kingkonghitme]

you are god of knowledge

[fire89zhao]

Does anyone know, is the sodium channel and potassium channel bi-directional or uni-directional?

[grodon909]

@fire89zhao Based on what he said (and I would need to review my biology text here, but assuming remember) since they are channel proteins, they molecules CAN go one way, but in practice they do no, due to the electro-potential difference.

[hduoawbdo221]

Sal! WHY have you stopped making biology videos!?

[vicandreatan]

@khanacademy This video make me understand and help me to figure out about the permeability of membrane towards k+ ions. besides, we call this process as resting potential? am i right?and i really appreciate ur hardwork in making these video thank you so much and keep it up =)

[Ultra9k]

I didn't see your original video but yeah, that's a major error you made there...

[ctkt21]

So I am taking a high school biology class and my teacher said that the reason why the inside of the cell is more negative than the outside is because of the 'leaky potassium' channels on the membrane. Is this true?? I am confused now. Please help! =)

[pitupraveen]

and just to raise a concern,,,, all this happens to a billion or so neurons continuously..... No wonder brain is said to be gullible,,, there are billion opportunities per millisecond for things to go WRONG :-)

[cmonbugmenot]

how is the membrane more permeable to K+ than Na+?

i don't understand because K+ is bigger according to period trends, and both ions are equally +1 charged

[mrthuvi1]

This is interesting.

[Roflshamans]

Ah very interesting. Thank you for sharing.

[JohnnyRa007]

Hi Khan How R u? I have a question that is a little bit off topic but i hope you can refresh my memory. Im writing my thesis about the information content of quarterly earnings announcements in the Netherlands. But i would like to know the reason why scientists in Finance but also in Accounting research always exclude Financial firms and Utilities? Best regards..

[FHomeBrew]

So it's mostly about the sodium and the sodium concentration ratio between inside and outside the cell?

[riveness]

Good correction.

[1fuseemerun1]

that's actually pretty interesting, so does this mean that there is some physical property of the K+ ion that allows it to diffuse across the membrane more readily than the sodium, or more simply, is there just more channels for K+ than Na+?

[brotherofiam]

@1fuseemerun1 Good question. My thinking is that if the pump is designed to maintain concentration gradients, and it pumps out 3 Na ions for every 2 K ions it pumps in. If maintaining gradient, more Na must have leaked into the cell than K leaked out, else over time wouldn't an imbalance be created unless there are other stabalizing mechanisms present to maintain gradient. to your ? maybe combination of factors: number of channels, membrane potential, and concentration gradient.

[FungusyHam]

So does this render sodium-potassium pumps kind of useless?

[khanacademy]

@FungusyHam No, you still need them to set up the concentration difference so that the potassium leaks out (and the pumping out of the Na+ helps as well)

[n0NcOn4MisT]

@khanacademy Please correct me if I am wrong, but surely, Stephen Baylor is not saying that K can get out through the channel (i would've thought the pump is the only outlet - if the channel could do that job, it can regulate, hence no need for pump)

What I understand from Stephen Baylor(from your quote of him) is that more K peremiates into the cell than does Na, so, we have a negative charge to begin with - the channel inlets are more accomodaing to letting in K than Na.

[brotherofiam]

@FungusyHam Sodium leaks into the cell via sodium channels, following its concentration gradient. Likewise potassium leaks out of the cell via potassium channels, following the concentration gradient for potassium. The purpose of the sodium-potassium pump is to pump the sodium that has leaked into the cell back outside the cell, and to pump potassium that has leaked out, back into the cell. The na+-k+ pump maintains the concentration levels so that gradient remains and process can continue.

[MisterAlexUk]

Thanks, you're so helpful.

[foodfreak45]

you are awesome

[alexanderblake]

Your voice is sexy.

[steamsword1]

2nd comment. I love watching these videos.

[slamnxgirlxjulie]

wow i would have never thought her would make a mistake!.. but at least he caught it :)