Membrane Potentials for beginners

Description of the basics of membrane potentials, including how a living cell sets up and maintains membrane potential. Includes basic description of the sodium/potassium pump and potassium leak channel.

[@redpilllense7125]

Professor, you ARE the "Master Yoda" of teaching This material!!!!!! Thank you sooooooooo much!!!!!

[@Jennnvang]

I really appreciate you explaining membrane potential in such a clear manner. I enjoyed the addition of the quiz at the end. 😁 Thank you!

[@supremerockstar101]

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Same with me

[@fdwt79]

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[@MaiSirry]

Wow, this helped so much! Best explanation I've watched so far. Thank you.

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[@TheFairy39]

Hello from a student in Graduate School! Thank you, Sir!

[@aileencanino6146]

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[@Dianna.279]

Thank you for helping me understand this better!

[@malloryconnors]

Really helpful! Thanks for posting, made it much clearer than my professor has put it!

[@RandyRotta]

Thank you Professor! This really helped solidify my understanding after my physiology lecture. The quiz was really helpful. Great content!

[@jason-ow8cq]

THANK YOU FOR THIS EXPLANATION!!!!!!!!!!!!!

[@olakosciuszko]

Again, the best video. Simple and logical. Thank you.

[@derickani1963]

Very good and smart teacher, you made me understand both Action potential and membrane potential easily.

[@Staysunny51]

This explanation is so much easier to understand than my professors!

[@yenthai6954]

I understand more when I watch your video. Thanks

[@shifengying136]

thank you Ren, it very clear to make me understand.

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[@hishammohamad5266]

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[@nelson1954]

Really like that quiz at the end.

[@DevinDillenger]

Great explanation thank you 🙏🏼

[@gloriaamankwaa2412]

Great explanation

[@brendaclayton415]

Thank you for the clarification!!!!!

[@zeenahchannel4041]

*Thank U So much Dr* 😭💙💙

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[@withbusybadhon8585]

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[@AileyIrvette]

Explanations are easy to undertand

[@sydneywall9938]

great video!!! really helped me understand membrane potential, thank you!!

[@Kh.Shafiq]

Very easy way... Thank you!

[@92_amnaafzal97]

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[@muthonimungaanne6742]

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[@eveibrahim6673]

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[@woillusion123]

Thank you Sir, great explanantion!

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[@boccaluppo930]

Thank you Dr.!

[@dannichols6261]

At 0:55 , just to be clear: you're measuring the inside *with respect to the outside* , correct? The inside is *more negative than the outside* , that's why it's considered to have a negative value, right? I ask because you said, "...because we're measuring relative to what's happening on the inside.", which *might* seem to mask that the measurement is of the inside *with respect to the outside* , ie, using the outside as the 'ground' probe, and the inside as the measured probe, right?

[@renhartung]

Yes, you are correct. The membrane potential is always measured from the inside of the cell and that is exactly why resting potential is negative.

[@chobechobe4139]

I am from India I like this lecture 👍☺️

[@chobechobe4139]

Thanks ☺️

[@mariatlopezleguizamo6483]

Thank You!!!

[@rainstormr7650]

awesome vid!...I so enjoyed watching it. Is the _difference_ in concentrations then of Na+ ions between the outside & inside of the cell, *Greater* than the _difference_ in concentrations of K+ ions [between the inside & outside] ? (since both are +ions)

[@renhartung]

I think the concentration difference of potassium is a slightly higher than the difference in concentration of sodium. It's not a real big difference though.

[@rainstormr7650]

thanks for the reply

[@JalYassin984]

Wow thank you

[@jeffreyheath2102]

Does the phosphate lost during the transformation from ATP to ADP which has a negative charge contribute to the negative charge inside the cell?

[@renhartung]

Yes probably, but it would be difficult to determine how much it contributes since the cell can't set up resting potential without the activity of the sodium potassium pump which constantly generates more phosphate as it breaks ATP. There are also other negatively charged ions inside the cell that contribute to the charge-. Na+ and K+ however are the major contributors in most cells where and how it matters (right at the cell membrane, and with changes in membrane charge).

[@jyotikhandhar6190]

Have to watch over and over again to understand exactly what potassium and sodium roles are

[@giardialambia711]

Very helpful ❤

[@HarpreetSingh-nw3ec]

Damn , now I understand why students go to foreign countries for higher studies. Great teachers !

[@leenunez242]

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[@ChillinwithNati]

THANK YOU

[@chenellkennedy2044]

yeyesssssss I answered every question. Thank you

[@abajahflorah9812]

Thanks so much sir

[@mamochannel1237]

Ty

[@venkatesanmunusamy7319]

Thank you SIR

[@sadik147]

Q1. why does ATP start to break down into ADP? is there any stimulation to trigger that? Q2. why 3Na ions are expelled out why not more than 3? and why 2 k+ ions are entering not 3?

[@PhD4me]

Professor, what is literally meant by 3 Na+ and 2K+ ions. Is it a measurement of number or actual volume? Also, how many Na+ are actually on the outside of the cell already? Thanks

[@renhartung]

What is literally meant by 3 Na+ and 2K+ ions is literally the number of these charged atoms that the sodium/potassium pump pumps across the cell membrane with each ATP molecule (at least that is how I understand it). The actual number of these ions that are inside and outside the cell would be in the billions or trillions (they are tiny)... We measure them by their concentration in millimoles (mM) and their actual concentration depends on the cell involved. On average the concentration of Na+ is around 15 mM on the inside of the cell and around 140 mM on the outside. On average the concentration of K+ is around 150 mM on the inside of the cell and around 4 mM on the outside of the cell. If you are in a class where you need to know the specific numbers, make sure you check your class resources for the specific numbers you are expected to know.

[@PhD4me]

@@renhartung thank you very much your explanation. I understand now 🙂

[@lauramanyeruke]

Thank you!

[@heenabasit4379]

do pumps are also referred to as carrier proteins?

[@renhartung]

No, carrier proteins are specialized proteins that selectively bind to a substance (usually to molecules larger than ions--- glucose is a good example) and allow that substance to diffuse across the membrane. My favorite example of this is the glucose transporter protein (glut-4 membrane protein). Sometimes carrier proteins are part of a secondary active transport systems, but since they do not use ATP directly they are not considered pumps.

[@rubyhourany9665]

thank you for amazing explication

[@jadumonigogoi845]

without sod pot pump conc of sodium is more in outside right.

[@renhartung]

If the sodium/potassium pump were not working there would be more sodium inside the cell, making the inside of the cell more positive. I hope that helps.

[@jadumonigogoi845]

@@renhartung you r right because conc . of sodium is more inside of cell due to presence of negative molecule proton ,org phosphat inside of cell.this is donnam membrane effect.but my question is albumin which is outside of cell do not play any role here ?

[@renhartung]

@@jadumonigogoi845 -- Albumin is a plasma protein (found in the blood). Albumin plays a major role in the osmolarity of blood and maintaining blood volume but I don't think albumin plays a role in membrane potential (at least not any direct role when it comes to neurons or muscle cells).

[@jadumonigogoi845]

now i understand albumin is not a charged molecule so it has no role of to cause gibbs donan membrane effect.due to unequal distribution of ion like protein ,org phosphate and sodium inside of cell is more than to outside of cell .now sod pot pump push out sodium to outside of cell in exchange of potassium and chloride to create negativity inside of cell to create resting membrane potential.

[@vanessapalmer7207]

Thank you so much now I get it

[@cherukunolla]

wonderful

[@bintmuhammad866]

thanks..

[@globalvarks1413]

So what exactly TRIGGERs the system to return from a state of HYPER-POLARISATION to its resting potential? Nowhere in the the 2 lectures (this one and the one which talks about "action potential for beginners") do you mention this SECRET.

[@renhartung]

There is no trigger for the membrane to go to resting potential. It's just the default state of the membrane. It's mostly about the sodium potassium pumps and the potassium leak channels (other ion channels contribute, but these two proteinsare the major ones). The presence of these membrane proteins makes resting potential the default state for the cell. Action potentials and other stimuli will disturb resting potential for a short time, but once the stimulus passes the membrane naturally returns to resting potential due to the continued action of the sodium potassium pumps and potassium leak channels.

[@globalvarks1413]

@@renhartung Thanks

[@MR.BLACK_sah]

the best

[@svitlanapotapova7396]

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[@louiedemontano7738]

Thank you so much doctor. You explain ed it so well.

[@pragnyadesai1734]

Excellent presentation

[@heenabasit4379]

pumps actually do the active transport means moving molecules against the conc. gradient that's why Na ions move outside and K ions move inside i.e. from low to high but how do the pumps know that where is the low conc. of the following ions and high conc...

[@renhartung]

Yes, you've got it... The sodium potassium pump is the pump you are talking about here. It moves three sodium ions out and 2 potassium ions into the cell. Both sodium and potassium are moving against their concentration gradients and this requires energy in the form of ATP... Active transport is absolutely correct.

[@heenabasit4379]

thanks☺

[@risks_3024]

I'm in grade 8 loll he explains really well

[@SanaBatool-q4k]

i passed your quiz 😋😁

[@mitaladenisa-andra4456]

Thank you!

[@Nsbdhd_321]

Thank you!