Correction to sodium-potassium pump video | Health & Medicine | Khan Academy
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- čas přidán 10. 07. 2010
- Correction to "Sodium-potassium pump" video. Created by Sal Khan.
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So humble. Thank you so much for posting the correction. I learn so much from this channel. Truly the best. We are all very grateful!!
Much respect for gracefully accepting and passing along the correction. Thank you!
@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)
Professor is savage.
thank u Mr.khan and Mr.steven
very helpful thanks
Thanks It makes alot more sense now.
Thanks Sal
Thanks Stephen
Very usefull
helpful, thanks
@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.
Yes!
I also want to mention there is another force acting to keep K+ in the cell even though it wants to go down its ionic concentration gradient, and that is the electrical gradient. As K+ leaves the cell the inside of the cell becomes more negative, and since K+ is positively charged, it wants to remain on the negative side (its concentration gradient). This is the basis for resting membrane potential, called electrochemical equilibrium and can be summed up by the Goldman equation
Is this the primary process by which the neurone returns to its resting potential of -70mv from the hyper-polarisation stage? Thanks
This is interesting.
Mr. Khan, I believe there was a minor mistake made in explanation of RMP explanation here. Specifically at ~ 6:08 where you mention potassium goes "against" its chemical gradient, via "leakage" through the cellular membrane. I believe potassium is going with its chemical gradient, as it is in higher concentration INSIDE the cell, and thus going outside of the cell during leakage makes it going WITH the gradient. If I'm mistaken, please excuse me. Thanks for your consideration.
The potassium and sodium ions both have specific channels for each. The potassium ions have leak channels which stay open all the time. The sodium ions don't have these leak channels. And that is why potassium is more permeable.
Do you have kids now?
Are you still Alive?
very good
Good correction.
why is there a carrier protein if there are channel proteins?
So when you say K can go through the membrance can it go out and into the cell? Gosh this whole K Na+ thing makes me sick.
As I understood, there are several competing factors:
1. Pump moving Na⁺ out and K⁺ in, thus creating different concentrations of sodium and potassium outside and inside.
2. Membrane not allowing Na⁺ to get inside, thus a higher number of sodium ions will exist outside than inside.
3. Membrane allowing K⁺ to leak out of the cell, thus restoring chemical concentration outside to be almost the same as inside.
4. Membrane allowing Na⁺ to leak into the cell when voltage difference becomes too high, thus acting as a safety feature.
As a result, a higher number of sodium and potassium ions will exist outside than inside, thus creating the voltage that we can measure.
We have been taught that another contributing factor to the maintenance of the potential difference is the presence of highly negative anions inside the cell which obviously have a profound effect on the negativity inside the cell. Also, due to the fact they are absent on the outside of the cell, this could be another contributing factor to the potential difference. Any views on this anyone?
The professor is wrong, too. Membranes aren't "highly permeable" to K+ which makes it easier for K+ to go down its concentration gradient, membranes are selectively permeable to K+ meaning there are more nongated K+ channels compared to nongated NA+ channels. Plus, intracellular neurons are more negative because of the negatively charged protein molecules (A-) which cannot cross the membrane. Inside the cell there are high concentrations of A- and K+ with low concentrations of CI- and NA+, while outside the cell there is no A-, low concentrations of KA+ with high concentrations of CI- and NA+
yeah that's a good point you are clearing but I think with the professors explamation we did get what it is like! at least I did understood it very well and that is exactly what he was willing to say, so the professor is not wrong:)
thnx annyways for clearing
@Jay Beamin, hey man, I am a little confused. If the protein channels are the ones that cause the cell membrane to be more negative than its outer compartment, because the "cell membrane is highly permeable to K", then why does the protein channels have specific permeability for only K in this case.
as stated by Jay Beamin above, He is absolutely correct. Infact I would like to add the fact that cell membrane is not at all permeable to POLAR substances (charged particles such as sodium and pottasium ions) so how do they move across the cell membrane, that is via specialized pathways known as channels which are in turn made up of proteins. (Read facilitated diffusion). If more pottasium is coming inside the cell membrane it either means that there are more number of pottasium channels or the activity of the pottasium channels is greater than that of sodium channels.
Very interesting. My visit to you channel was due to self educational reference as I will be enrolling Into surgical technology. My prerequisites prior was all mathematics and physics. Which is far from the study of biology. But find equally fascinating. Thanks for you information. I’m reading an A&P text and it dose not seem to articulate these concepts as well as you’re videos.
Do you have a source that I can check out?
2nd comment. I love watching these videos.
Does the potassium, in this open channels in the membrane, only go "out", or it does go "in" from outside of the cell too?
Can you talk more about channels? I haven't seen all your videos (yet) but so far channels aren't covered much. I am not sure they are covered much anywhere either but they seem very important.
wow i would have never thought her would make a mistake!.. but at least he caught it :)
Nice. Just a linguistic correction if I may, it is pronounced stee-chiometry. The combination "oi" in greek is pronounced "ee".
@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.
so, is this an explanation for the potassium leak channel?
Does anyone know, is the sodium channel and potassium channel bi-directional or uni-directional?
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..
Hi, I find your videos extremely helpful and interesting in understanding physiology. I have a question regarding this video I wonder if you can answer. The contributor to this video claims that the main cause of the inside of a cell being more negative than the outside is due to the membrane being more "leaky" to K ions than it is to Na ions. However, I'm struggling to understand this because surely positive K ions would therefore leak quickly into the cell, making it more +? Can you explain?
Sam Travis for every 2 potassium ion that leaks into the cell 3 sodium ions leaks to the outside therefore creating the electric gradient.
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
Sal! WHY have you stopped making biology videos!?
Actually SAL, this sodium potassium pump main purpose is to maintain stability in in nerve cells that carry impulses
So does this render sodium-potassium pumps kind of useless?
how is potassium more permeable than sodium when the potassium ion is 30% bigger than those of the sodium?
@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.
Do you have kids now?
Guys can anyone explain y the need of pumping both 3 Na+ and 2k+ to create potential difference, we could have pumped only Na+ or Only K+ so that there exist a pd
but surely, due to the 'high permeability' of the membrane to K, the K can just as easily enter back in, down its conc. gradient via the same ion channel it exited/leaked out?
The inside of the cell has a high concentration of potassium ions compared to the extracellular fluid outside the cell, which is the reason they flow out of the cell through leak channels to begin with. The potassium ions will not "easily enter back in, down its conc. gradient", as going back into the cell would be UP its concentration gradient. The plasma membrane helps to maintain this steep gradient by pumping Na out of the cell, and K into the cell.
He did this 2 years ago, do you think he reads these comments?
👏👏💯💯💯💯
Wait so if K is more permeable to the membrane, wouldn't more K ions want to come INTO the cell where it is more negative? Towards the end of the video you show the potassium ions want to go outside of the cell, and have an easier time doing so. But wouldn't it be the opposite? So is the 3rd sodium thrown out the cell to lure the potassium inside of the cell out of it?
The potassium leak channel isn't driven by charge, but rather concentration(diffusion). Since the concentration of potassium ions is higher inside the cell, they will diffuse down their concentration gradient to the outside of the cell.
Rather than having a wrong video and then making a correction video, why not remove both the videos and a more reliable and accurate single video. just imagine the plight of the students who have watched your initial video and not watched this correction video, they will pickup wrong concepts
So, If I want to correct sodium-potassium pump I should take more Potassium. Sorry for my English)
🤦🏻♂️
Personally I like Bozeman better
66tryyt
this sucks I was totally into and learning this until you added this BS ugggggh redo the video with corrections
wahhhh, wanna stop whining