The Nernst Equation and Equilibrium Potentials in Physiology

In this video, I introduce the Nernst Equation and explain how it can be used to calculate the equilibrium potential of an ion (with sample calculation). Additionally, I discuss the significance of the equilibrium potential and its role in determining net ionic movement.
LINKS TO RELATED KZbin VIDEOS:
-Ionic Basis of the Membrane Potential -- • The Membrane Potential...
-Ionic Basis of the Action Potential -- • The Action Potential: ...

[@ms.flawed]

Not every teacher can master the art of explaining complicated topics so easily... The fact that you did and you thought of posting it online is wonderful.. I wish you would keep publishing videos like this... We really need more teachers like you...

[@PeteMeighan]

Thank you--I sincerely appreciate your kind words and encouragement. I'll be publishing more videos in the near future.

[@studytuberrohan2998]

It's amazing to think how a handful of benevolent teachers like you sir can profoundly influence millions of students' education.

[@Casualbystander]

Thank you so much for this video! Just started my neurophysiology course and was asked about the Nernst equation. This was so thorough and I love the example you provided!

[@PeteMeighan]

Thank you for the kind words! I really appreciate it. I'm glad this video was helpful Best of luck to you!

[@vitoria96634]

Thank you so much, I read about it but I still had some doubts about the subject, but watching your video cleaned up the issues for me! Life saver!

[@Qamar.113]

I love your way to explain which is so simple and conceptual.Keep it up. Thank you!

[@lascacu6653]

Mind blowing video!! Loved it.

[@thematureneuro468]

without the doubt the best explanation to Nersnt equation and its application I have heard to date. Thank you!

[@georgegrubbs2966]

Cleared up some questions I had after reading Hodgkin-Huxley in "Neural Dynamics". Great videos and clear explanations. Keep it up.

[@biancapasca-saturn6269]

This video is very helpful for me! My teacher explained this to me twice and I couldn't wrap my head around it. The visual representation is what I needed! Thank you!

[@PeteMeighan]

I'm glad this video was helpful! Thank you so much for the kind words!

[@andrazmatos6688]

I need to know about the Nernst equation from a chemical perspective. Yet this video has shown me so much detail and easy explanation that I couldn't understand with chemical videos. I love when the sciences mix, coexist and help each other. Thanks for the video

[@blueballoon7832]

i'm pissed that a free youtube video is better than professors that I paid ten of thousand of dollars to attend.

[@weirdoes]

Thank you so much! I was so stuck on converting ln to log so I could never get the right mV. I finally understand this. You've been a great help!

[@PeteMeighan]

Hi Janelle. I'm happy that it was helpful, and I really appreciate the positive comment. Thank you!

[@alexyen5326]

Mind-boggling clear explanation, greets from Taiwan ☺️

[@chakantaote6013]

I was asked this question during a physiology lecture and I got it wrong and none of my classmate could rescue me. Thanks for this wonderful , short video yet to the point!!

[@docbry2443]

Thank you so much. The formula in the current guyton still uses the negative version this really made it clear to me now.

[@ahnaf_akif_mbbs_bd_ksa]

sir your videos are too valuable to be explained , very Concise and top class representation . Really we expect such more videos from you .

[@GpDarkness]

You explained it amazingly (in a combination with the next video "the membrane potential")!!! Thank you sir!!

[@PeteMeighan]

You are welcome! Thank you for the kind words!

[@inesbauer3360]

Very precise and straightfoward!! thank you for the amazing video

[@PeteMeighan]

You're very welcome! Thank you!

[@sanjasossi376]

Thank you for all of your videos! They're really very helpful!

[@PeteMeighan]

You're very welcome! I'm glad they were helpful and I appreciate your positive comment!

[@girlsbehindbars2298]

thank you for the best video explanation Pete!

[@Gangsta0wns456]

This explanation is phenomenal!! Thank you!

[@PeteMeighan]

Glad you think so! Thank you for the kind words!

[@sherimarcantuono9979]

This was great and exactly what I needed! Thank you

[@PeteMeighan]

Thank you for the kind words!

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i am a indian and is currently attending high school and the lecture did help me a lot!!!! thanks\

[@hanheejo2360]

This video is amazing! Thank you so much!!

[@beinghimself]

Please continue what u do this is unique educational content

[@pasdpasse439]

Very good video, you're an excellent teacher!

[@Lauren-te9xh]

Amazing video. Very well explained. Thank you so much

[@PeteMeighan]

Thank you for the kind words Lauren. I really appreciate it!

[@taladiv3415]

Thanks for this nice refresher video!

[@tahurahossain6012]

Excellent content!

[@rolandovera1271]

Thank you so much. Passing my exam because of you

[@eunicemwicigi8104]

thank you so much for this amazing video!!

[@CandiceKoolhaas]

This was SO HELPFUL!!!!!!

[@PeteMeighan]

Glad this helped! Thank you for the positive comment!

[@garekbushnell3454]

Clearly explained, thank you sincerely.

[@PeteMeighan]

Glad it was helpful! Thank you for the positive comment!

[@lauragraphics6757]

Thank you sos so sos much for this video- I know understand everything! God bless you

[@PeteMeighan]

You are welcome! I am glad it was helpful!

[@eGreyWarden]

This was really helpful!!! Thank you very much!!!

[@PeteMeighan]

I'm glad it was helpful! Thank you so much for the positive comment!

[@andre178]

best explanation for what the heck the electrical gradient is, have not found this in any other physiology explanation

[@PeteMeighan]

I really appreciate the kind words. Thank you!

[@fatouyazmeen3724]

Nice! Thanks for the perfect explanation on this concept :)

[@PeteMeighan]

You're very welcome! Thank you for the kind words!

[@halicusdiaarcan102]

Another great video :) thanks!

[@raghvendrasharma2329]

Thank you very much ! Your explanation is great.

[@PeteMeighan]

I sincerely appreciate the kind words. Thank you!

[@Jojo-xe9nu]

Thank you so much!! The explanation my professor provided was so confusing this really helped clear it up :))

[@PeteMeighan]

I'm glad this video helped. Thank you for the kind words!

[@jeffreywhite7867]

Great work!

[@kiwipie3386]

Super helpful, thank you!

[@PeteMeighan]

I'm happy that it was. Thank you for the positive comment!

[@marianklose1197]

thanks! very well explained!

[@iriswhite3184]

I was so confused, but it actually makes sense now. Thank you, wish my professor thought like this!

[@arshithgowda8728]

Lecturer ❤❤is soo knowledgeable

[@charlesdarwin9654]

Thank You King.

[@nicolasfandrich9038]

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[@mariakara4848]

thnx a lot this morning had 1hour lecture about it and couldn't understand till now in 10minutes u gave what my professor couldn't explain 😅

[@gujiyarai6802]

Wow! You are a great teacher.

[@PeteMeighan]

Thank you! I appreciate it!

[@MsDDaisy]

Thank you for this video!!

[@PeteMeighan]

You are welcome! I'm glad it was helpful!

[@hamzaiqbal212]

Great Video!

[@PeteMeighan]

Thank you!

[@stuartdejonge2769]

this video is awesome, thanks!

[@PeteMeighan]

Glad you liked it! You are welcome

[@alexasoto8653]

Thanks so much I finally get it now!!

[@PeteMeighan]

Glad I could help!

[@Nexus5273]

This video was very helpful... Thank you..

[@PeteMeighan]

I'm glad it was helpful! Thank you for the positive comment!

[@fushi7853]

Thank you so much I have a quiz about this tomorrow this really heleped

[@PeteMeighan]

I hope your quiz went well! Thank you for the positive comment!

[@woah1887]

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[@ChazinSthl]

It took me 4 years to understand this concept. 4 years!

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[@user-yw9cd5pv3k]

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[@jonahansen]

Faraday constant relates charge to number (moles), not mass. Excellent video zeroing in on the fundamental idea of balancing energy change of electrical versus chemical potentials.

[@PeteMeighan]

Haha--good point! I think when I said "mass" in the video, I was speaking a little loosely for a moment. I'll see if I can squeeze in a correction/clarification in the video. Thank you!

[@cynthiaoliver4469]

Thank u sooooo much for this video 😄😄

[@priyadharshini5160]

Thank you so much for the explanation! I had a qn: What does the sign mean? What is the difference between an electrochemical gradient of +80v vs -80v

[@justsarah1712]

Amazing

[@ricardotorres8114]

well explained

[@woonseob]

great thanks !!!!

[@alexbarraza769]

Nice video, too helpful! But why the ln can changes to log base 10?

[@KimNguyen-gz2nx]

Great video❤️

[@PeteMeighan]

Thank you for the kind words!

[@queenzht]

Thank you ❤

[@muhammadjunaidali142]

awesome

[@chrisli9685]

Love this video!!! I just saw your bio online that you studied philosophy in undergrad. How did you go from philosophy to physiology? I'm pursuing graduate study in biomedical science now and my previous undergrad experience hails from the humanities, (English specifically). I'm curious if you would post about your transition and how you got into physiology from philosophy and what challenges you faced if any.

[@PeteMeighan]

Thank you for the kind words and for your interest in my background! I was always interested in science, but couldn't stomach the way it's typically taught at the undergraduate level. I found the heavy emphasis on facts / memorization supremely boring. I fell in love with physiology because it is a vast, multi-disciplinary scientific arena that invites thought and emphasizes process, which can be understood by applying fundamental physical principles and molecular mechanisms. I firmly believe that a strong background in the humanities--which cultivates creativity, critical thinking and abstraction--is an excellent way to prepare for graduate-level study in the biomedical sciences. The main challenge, however, was having to maintain a single-minded focus on my graduate project. Furthermore, watching the diverse intellectual interests I once had whither away as I immersed myself in the narrow area of reality and thought I'd carved out for myself was a little depressing. However, I feel like I was able to compensate for that by becoming a bit of a generalist in my teaching and research. I believe that my background in philosophy/humanities made it easier for me to intellectually engage in areas not directly related to my research. Hope that helps! Let me know if you have any additional questions. Be well!

[@zacleveroni4666]

@@PeteMeighan I'm about to graduate with a bachelor's in philosophy and am trying to go into neuroscience. I'm finding the immense technicalities of organic chemistry difficult to grasp, to say the least. Your video is the only one so far that explained the Nernst equation clearly enough for me to understand, and stumbling across this comment about your background gave me some much-needed hope. Thanks for the video and for the boost.

[@PeteMeighan]

Thank you for the positive comment--I enjoyed reading it! I can definitely relate to your experience in O-chem. It's easy to get discouraged as you are toiling away on pre-reqs that have little utility for your actual academic/intellectual goals. Keep going. Life gets better once you push thru that BS and are able to focus on the areas that interest you.

[@filizkorkmaz]

Pete Hi. I was wondering if I could use a couple of your visuals in my Biophysics class. I will definitely give my students the link of this video. I absolutely loved the way you presented the subject.

[@PeteMeighan]

Absolutely--I'm more than happy to share the images. I have them imbedded in a PowerPoint file. Email me at [e-mail] and I'll send them to you. Thank you for the kind words. I sincerely appreciate it!

[@MrYahya0101]

Regarding the battery, is the positive electrode is the anode and the negative electrode the cathode? Because cations (e.g K+, Na+) move to the cathode, the cathode must be the negative electrode right?

[@kruthikakv8824]

Thank you

[@user-vm7we6bm7x]

Thank you sir

[@billbilalis7547]

Ηi, may I ask why dont you include the electrode standard potential in the Nernst equation ? Thank you in advance.

[@meekleak9597]

Thank you so much

[@PeteMeighan]

You're most welcome

[@uzair6034]

easily explained well done work😂

[@rafiyahkhan3758]

Thank u sir 🌍

[@PeteMeighan]

Most welcome

[@jaycobdavis3467]

Hi great video. I'm doing a module in Bioelectricity at university which is based on the book bioelectricity: a quantitative approach. Just wondering what the best learning resources you've found for this field. Thanks

[@PeteMeighan]

Thank you for the kind words! The main neurophysiology texts that I've leaned on over the years are: "Foundations of Cellular Neurophysiology" (Johnston and Wu); "Biophysics of Computation" (Koch); and Bertil Hille's classic "Ion Channels of Excitable Membranes"

[@lauramonica6924]

Very grateful for this video- thank you so much. May Jesus bless you

[@PeteMeighan]

Thank you Laura. I'm happy this video might have been a help to you, and I sincerely appreciate the kind words.

[@gehadsamir5663]

thank you

[@renad7548]

The sad thing .. when your native language is not English, such a great video I wish I could understand it 100%

[@MrNoahMatthews]

Can you explain how the constants end up 61.5? No matter what I do, I can not seem to get that. When I multiply RxT and then divide by F I get... ((8.3)(310.3))/96500=0.026689

[@PeteMeighan]

Hi Noah. No problem--the last steps are to convert from the natural log (ln) to the log base 10 (log), with the following step: 0.026689 x 2.3 ; and then convert from V to mV by multiplying that value by 1000. You should end up with ~61.5 mV (exact value will depend on how you round out your numbers). Hope that helps!

[@johnsmith-yv7rp]

What is the 'battery' in the case of the body?

[@abrahamudodong502]

Please, what values of R, T and F are used to derive 61.5?

[@polaroidandroidjeff6383]

How did you jump from them letter to 615 over z?

[@hideousred]

god bless you

[@tanja2058]

Great video! but I have a question, If the equilibrium potential is -80, is the inside always negative?

[@PeteMeighan]

Thank you so much! Most cells are only permeable to K+, so for them the answer is yes. However, some cells--such as neurons and muscle cells--can become (briefly) very permeable to Na+ (Eq. Potential approx +60mV) and/or Ca2+ (Eq. Potential approx +120mV). For these cells, the membrane potential can become inside positive. Not to plug my own videos, but if you are interested in seeing how that works, check out my video on Action Potentials ( kzbin.info/www/bejne/b6m9coxobbuWpas ). Thank you again!

[@tanja2058]

@@PeteMeighan Thankyou so much!

[@littletravel]

Really nice presentation. I would be happy if you clarify one of my question. Around 9 min, you are saying -80 mV. Can you please tell me what is negative volt mean? what is the significance of '-' and how it would be different if the result comes positive?

[@PeteMeighan]

Thank you for the kind words! Voltage is a relative measure. By convention it is measured as the potential difference inside of the cell compared to outside the cell. This is similar to how blood pressure is the pressure difference inside the vasculature compared to the atmosphere (MAP ~= +100 mmHg). Or how atmospheric pressure is the pressure of the atmosphere compared to a vacuum (~= +760 mmHg at sea level). In an alternative universe, blood pressure could be expressed as the atmospheric pressure compared to inside the vasculature (i.e., MAP ~= -100mmHg). For voltage = -80mV, this is equivalent to having an 80 mV battery, but with the negative terminal oriented to inside the cell (positive terminal outside). Hope that helps!

[@littletravel]

@@PeteMeighan thank you so much for detailed answer.

[@sharonlefa1634]

thank you so much for the great explanation - I have a question, what does the sign represent in the answer we get from the equation ?

[@jadumonigogoi403]

Any good derivation of this equation.

[@iamliefelmire1759]

quick question, why is -50 mv smaller rhan -80? when technically -50 is bigger, do we ignore the negative sign when comparing voltage?

[@PeteMeighan]

Good question! Essentially that's the case. -80mV is an electrical gradient / membrane potential that is larger in magnitude than -50mV. The sign indicates the polarity of the electrical gradient (where, by convention, it is the voltage inside the cell compared to the outside). Hope that helps!

[@abrarbaloch5710]

From where does the battery come? Like who provides the voltage so that the ions do not flow out during normal physiological conditions

[@PeteMeighan]

The battery symbolizes the membrane potential. It is the membrane potential that accounts for the electrical gradient that influences net ionic movement. To see how that works, check out my video on the membrane potential: kzbin.info/www/bejne/rIrGcnuXosp8fdk

[@user-bc3cn9kl3k]

6:35, how did you get 61.5? or why is it 61.5? I did the computing but for a different value

[@PeteMeighan]

What value are you getting? The most common errors are to compute using temperature in degrees C (rather than degrees K), forgetting to convert ln to log, or not converting V to mV.

[@sebastianemilio4837]

how did you get 61.5 :((

[@nellvincervantes6233]

Hmm. I am looking for Nernst-Planck Equation. Where the equation is: J = -D*gradientC - (zF/RT)DC*gradient potential + Cv.