Gibbs-Donnan Equilibrium and the Membrane Potential

[@llkeeley]

Thank you for letting me know that, even in retirement, I am still able to help classroom education. LK

[@georgelsoare8157]

You are still doing so :) congratulations! Thank you so much for your work.

[@emiellebloemendal1960]

This tutorial was used for a 3rd year physiology lecture, at the University of Pretoria, thanks for making studying easier :). This tutorial is pretty cool.

[@sounakrakshit7312]

Thank you so much..even after 10 yr it's continuously helping student across the globe..

[@llkeeley]

If I understand your question correctly, the charge difference occurs across the membrane not on one side. On either side the numbers of =/- charges are equal but, between the two sides one side has more + charges vs - charges so the charge occurs between the two sides.

[@ahmadpavadiya]

4:22 is deciding factor for gibs donnan equilibrium Thank you for clearing my doubt ❤️❤️🔥👍

[@fattons92]

really really really really thank u! i was loosing my mind trying to undertand it!

[@ahmadpavadiya]

Me too bro

[@Klatregutten]

Sweet fast review of the Donnan Equilibrium. Makes understanding the phenomenon much easier!

[@llkeeley]

Thank you. Happy that you found it helpful.

[@omkarchavan5940]

How did you calculate ion concentrations at equilibrium?

[@llkeeley]

Good point. This is strictly a phenomenon of solutions with any semi-permeable membrane with common, permeable ions on each side and an impermeable ion on one side. It would happen with a synthetic membrane or a biological one. Since this is a physiology education website, I relate it to biology.

[@michaelhartman1656]

Thank you so much for this video, nicely done, very graspable.

[@llkeeley]

You are most welcome. In my opinion, this is one of the most difficult concepts in physiology to get one's mind around, and I am happy if I have been able to help you understand it.

[@maryamjaved1571]

Thank u so much for this wonderful video.It made me understand the entire topic so easily.

[@llkeeley]

You are welcome. Happy that I could help you understand this difficult topic,

[@anonymea4326]

Even after so many years your video is so helpful! thanks!!

[@llkeeley]

You are welcome

[@samuelmcgill9168]

K+ and Cl- are should be opposite in relative size

[@haroonrashid5085]

Crystal clear explanations . Thank you

[@llkeeley]

My pleasure to be of assistance

[@dojoofficial]

Thank you so much Sir. Very clear explanation.

[@llkeeley]

There are many impermeable anionic species (Pr) inside the cell, but it is not necessary to know their content, since they have no equilibrium. They set the conditions for the movement of the permeant ions (i.e. negative inside). The Nernst Eqn is based only on the equilibrium of the permeable ions therefore, the charge is Ko vs. Ki; [Na]o vs [Na]i; and [Cl]i vs [Cl]o. [Pr -] = 0 outside, so they do not contribute to the final equilibrium or the calculation which is entirely the permeable ions

[@kellieskawewe7505]

U are the man sir

[@llkeeley]

Thank you, I am happy you found it of value.

[@flageyme]

This was really well done!! thnx a lot from a student in belgium ;)

[@hitokirib2229]

Why does the number of penetrable ions (which is greater on the outside) make the inside of the cell more negative than the outside if both K+ and total negative charges are more on the inside than on the outside at equilibrium?

[@subhrabhattacharjee2538]

Because of concentration gradiant

[@taeilshighnotesinchain5621]

Very clearly explained. thank you very much.

[@llkeeley]

Thank you. Always happy to know it was useful.

[@aklilukefyalew999]

Really helpful, Thanks

[@lingyuzhang7190]

Hi, just a quick question: why [K]inside*[Cl]inside = [K]outside*[Cl]outside at the equilibrium? thanks!

[@emanuelferraro2267]

How can one side have a negative charge if the numer of cations and anions in it it´s the same?

[@llkeeley]

Thank you for the nice compliment. I use Adobe Flash.

[@DarrellBarnes]

Does the slow movement of K+ back and forth across the membrane explain why my blood pressure response to eating too much sodium seems to be delayed a day or two after the incident? It seems like I get both immediate and delayed effects of Na+/K+ consumption reflected in my blood pressure. This video was assigned by Dr. Turnbull at Clemson for a Zoology class! Interesting!

[@llkeeley]

I do not think so. It may be slow in my video, but I am illustrating events not how fast they occur in reality. Your body is constantly adjusting your blood pressure based on its regulatory signals and needs. If these are not functioning properly, I recommend you discuss this with your doctor and follow his advice. Tell Dr. Turnbull thank you for me.

[@parampreetkaur5829]

Really good. Thanks dear

[@TuNguyen-yv7lv]

could you answer my question, please. why [Na]1[Cl]1=[Na]2[Cl]2. if i [Na]1x[Cl]1=(x+y)y=[Na]2x[Cl]2=(x-y)^2 xy+y^2=x^2-2xy+y^2 x=0 or x=3y so it isn't true in every situation. could you explain why our bodies follow this rule. if it is not correct so the example at 6:49 is not objective, it just reflect a special situation

[@llkeeley]

I apologize but I have no idea what your formulas are with all the double arrows, or how they relate to what I show in the video. The at equilibrium

[@jainamshah4819]

Excellent very nicely explained thank you

[@llkeeley]

You are most welcome. Thank you for the comment.

[@RomeroPiano]

Does this apply for capillary phenomen about oncotic pressure?. Because the compartiment there are Intravascular and intersticial and the negative protein is Albumin.

[@llkeeley]

Yes, it would. Osmotic pressure is for water movement and if there are unequal amounts of solute in solution, there would be a lower water concentration in the more concentrated solution so water would flow into the more concentrated solution. But the picture is complicated in cells in that you have differential permeabililties of membranes to ions, and also active and passive ion pumps and channels in the membrane. This explanation is a relatively simple system where everything is based on differential membrane permeability and 3 ions of which one is impermeable. As explained in the last scene where I talk about the cellular system, be aware that the GB-equilibrium only occurs along the cell membrane whereas the osmotic effects involve the entire cell and its entire solute concentration relative to the extracellular milieu. I am not sure that is a very satisfactory answer, but the physical electrochemical properties still always apply but are more complicated in biological systems. That is why we use 0.9% saline solutions in physiological systems: to maintain both isotonic conditions and as a source of sodium and chloride Hope that helps?.

[@RomeroPiano]

​@@llkeeley Yeah, I got it. I was just wondering...if something similar occurs when we talk about insterticial and intravascular space I would assume that there's a membrane electric potencial around every capillar. Look this image > www.mailxmail.com/curso-equilibrio-hidroelectrolitico-acidobasico/distribucion-electrolitos-organismo Na+ are gonna start to move to insterticial space creating a potencial 'cause negative-charged protein can't get through the endotelium.

[@noujumnoor715]

thank you so much for this video... 😊

[@llkeeley]

You are welcome LK

[@Sarah-gw7bj]

really helpful, thanks a lot!

[@sweetpicklez]

Thank you this was very clear!

[@kpshekhawat]

i am biochemistry student. the topic is nicely explaind

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[@llkeeley]

Thank you

[@BAYK8644]

Thanks a lot for this very helpful and inspiring video!! I have been brooding over one detail: For calculation of Gibbs-Donnan effect on the resting membrane potential (as opposed to the action of the sodium pump) it would be necessary to know the concentration (number of charges?) of the intracellular impermeant anions in an actual (mammalian) cell (e.g. a neuron). Do you have any information about this concentration? I was unable to find usable numbers. Thanks again! CR.

[@rinafadlina3905]

Thank you! I am finally able to understand this :D

[@luxemshah8801]

thanks!want to see more!

[@clarashakivsoyris1336]

Hi,at equilibrum - does the osmalarity is equal in each side ?

[@llkeeley]

No. If one is dealing with a semipermeable, non-living membrane the molarity of solutes is higher on the side with the impermeable anions. So water would flow by osmosis from the side with only permeable ions such as Na, K, and Cl into the side with the non-permeable ion. In living cells, the membrane is more complicated with regard to differential ion permeablities. Cell membranes are very permeable to K+, about 50% less permeable to Cl- and only about 10% as permeable for Na+. Also, there are large cationic proteins in the extracellular fluids of animals, so the osmotic effects are offset. Only in extracellular fluids of distinctly higher or lower osmolarities would there be a problem or, possibly, if the cells were injured and their membrane permeabilities damaged.

[@Sara3346]

Biological membrane or a sheet of plastic may I ask?

[@Mansoorali-zq1rp]

Thanksssa for this

[@clarknielson4181]

God bless you.

[@llkeeley]

Thank you. I need all the help I can get.

[@manigandanc3752]

Larry Keeley thank you

[@ayaboussaada7209]

thank you

[@MysticMD]

thanks so much :)

[@llkeeley]

+Zi Gyllenhaal You are welcome. LK

[@anushaanthony3315]

thank u

[@llkeeley]

You're welcome

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