LOOP OF HENLE explained!!

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A detailed explanation of how the Loop of Henle helps to concentrate urine using the countercurrent multiplication mechanism. CLICK HD for better quality ^_^, Enjoy!
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FAQs [disclaimer: these answers are as far as my knowledge stretches, if you have a better explanation inbox me, I would be happy to hear it ^_^]:
1) Ruz, why doesn't the osmolarity of the interstitial fluid change when water leaves the descending limb?
Well... from what I understand: it is primarily because the water in the descending limb is leaving passively (as opposed to being pumped out) whereas the NaCl in the ascending limb is being actively transported out. Therefore, the solute concentration in the medulla is being added to at a far quicker rate than water molecules are able to leave to dilute it.
Business enquiries: [e-mail]

[@biomedsessions]

Check out our video on hyponatremia (hyponatraemia) kzbin.info/www/bejne/hIrbm2qZa66LqNU in which we give a detailed overview including classification, investigations, and management. Enjoy ^_^

[@MusicMLady]

This was about 1200 times better than the nonsense my lecturer was going on about.

[@sophiaisabelma]

sometimes I feel like professors think they know their shit so well that they just talk about it when they get up there and sometimes they end up going in circles or not explaining things or just don't do a good job.....these videos are so much better b/c someone actually put the time into organize their words/thoughts and present it in a graspable way..... *eye roll* i feel your pain

[@millie4785]

i see what u did there.

[@treestumpisland5586]

Night before my final. 2 AM. Still confused because my professor made it all confusing. Now it makes so much sense

[@ivanaznar6495]

Hiperosmotic nonsense... 😉?

[@briandude7774]

Same! 10/10 explanation

[@argrig]

This video does a better job than 95% of salaried academic lecturers across the world!

[@alf821]

maybe 96.25% ! Very well done. Most physicians are ignorant of this.

[@eldrienadsilva3385]

This person deserves a cookie.

[@rebeccawan3088]

@@eldrienadsilva3385 I look into my lecturer's note. It is just a pdf with links to youtube videos... Not even joking. The only thing he typed himself are the titles......

[@satishHembrom01]

From India..

[@timestamp2525]

How did you arrive at this number?

[@katzepa9434]

9 years later and this video still helps med students

[@viviandarkbloom172]

No other video/lecturer can ever beat this explanation. Thank you Luz!

[@alexandria4167]

Holy crap! This video is so concise without overly simplifying things. Amazing, I really appreciate that you brought in the values of osmolarity, this is essential to understand why it's a multiplier!

[@nicolaconquest1695]

This is one of my go-to videos for renal physiology - completely takes away the mystery of countercurrent multiplication! Thanks!

[@ahmadharis518]

So simple and yet so effective. I wish everyone taught this thing the way you did. All these physiology books are making an almighty holy mess in trying to explain this simple mechanism that you have explained so brilliantly!

[@bridgfordartsandsciencesli6861]

Hi Ruz. I have been teaching Biology for thirty years - and this is amongst the best teaching I have ever seen. You are seriously good at this.

[@clarapfeiffer5468]

Amazing video! I'm a med student and this is the first time I fully understood the countercurrent multiplication. Thank you for the great video! If you were thinking about making another video and are looking for a topic: The Physiology of breathing is a suggestion of mine.

[@vb9490]

I agree, that was a very hard concept to wrap my head around when we learned respiration in med school

[@benm2156]

you don't learn this before going to med school????

[@dimkacracker]

saw this in physiology in undergrad school. Probably is repeated in med school.

[@PatriciaSmyle]

@@benm2156 No, not in Europe, you literally learn it all in uni

[@grapejuice3988]

4 years on, how’s med school?

[@samanthatarantino721]

First time I am writing a review ever, because I have to say THANK YOU! The loop of henle was just not clicking and I've probably watched about 10 different videos before this one. You did an amazing job breaking this down and showing actually how it's set up. Most other videos just say how ions move out and water moves out and this sets up a gradient, but you showed how and why. Thank you so much it finally clicked!!

[@michellelehmann-lopez1630]

I hope you are well, Ruz. You teaching ability is amazing. You truly have a gift!

[@rocioubillabautista8349]

Thank you so much!!! you managed to make easy and understandable a rather dull subject when it is read on a book, and you did it with a high and accurate academic level!

[@copypaste1358]

This is gold! Other videos that I've watched were not very helpful but this video is :D

[@fridericusrex9812]

This is hands down the best explanation of countercurrent multiplication on KZbin. Thank you.

[@LilyAlmond]

This was fantastic for my academic course, thank you for explaining it better than anyone else!

[@wasekbd]

Books are confusing... Your explanation together with the animation makes the jaw breaking counter current mechanism crystal clear!

[@biomedsessions]

Hehe ^_^ yes some books can be quite confusing! Thank you for your comment.

[@ericwolfe5574]

I love you. You outproffed my prof.

[@biomedsessions]

Hehe, I'm glad the vid helped you ^_^. Thank you for watching and commenting :)

[@aryaa3998]

+Biomed Sessions I love you too.

[@raxorium5851]

I've been trying to wrap my head around this, several hours of studying in various positions and googling, but this video explains it perfectly, it connects everything together, I LOVE YOU, THANKS!!!!

[@imanalkole919]

You have saved my life. Thanks. Did not understand a single thing of this, until you explained this to me! You made it so simple and understandable!

[@amine3226]

You are an absolute blessing! I struggled to understand this concept for so long, I almost gave up, but after watching your video I feel like a huge mental block has been removed!!! Thank you so much for all your hard work in making these, I appreciate all your efforts!

[@biomedsessions]

Wow! I'm glad that its helped you Armine 😊. Keep an eye out for more videos coming soon. Thank you for watching and commenting ^_^

[@danielhallriggins9008]

SO well done!

[@biomedsessions]

Thank you for your comment Daniel ^_^

[@nellyhoffman6194]

GREAT JOB

[@jenlagos808]

i watched this three times since my teacher showed the video too me. such a good explanation. it's clear to me everytime i rewatch. thank you!

[@nancysong9581]

Thank you so much!!!! I have spent hours looking at this topic in the textbook and you only took 5 minutes to explain this so clearly!!!! Finally I can understand this mechanism.

[@farbodniazi6504]

One of the most efficient and well-explained videos of my entire life

[@biomedsessions]

I really appreciate your comment Farbod ^_^

[@Hansblow12]

Biomed Sessions Nicely presented, thank you.

[@biomedsessions]

Thank you for your comment ^_^

[@lisachater8076]

Even if I'm a french student I understood this video 1200 times better than my course

[@mistrotman420]

This is the 2nd time in my uni career that this video has helped me, kudos!

[@wetgyjnmb]

To the point and clear, eactly how it should be- thank you so much. More videos would be highly appreciated :D

[@biomedsessions]

Thank you so much, I really appreciate your comment ^_^

[@poincareconjecture5651]

My goodness, that is so well done, i bend my knee!

[@alvinjosephpineda1391]

Thank you so much! I really appreciate how you simplified everything! You deserve some sort of award for this one! More power!

[@nightbot41]

This might be the best explanation on KZbin. Well done.

[@david0hinckley]

This is probably the third time I've had to learn renal phys (each in a different course), and I think you are the FIRST person to mention that the passive diffusion of water out of the descending limb does NOT change the tonicity of the medulla! That makes all the difference! I have always gotten confused because I have been thinking of it as a closed system, where the water would lower the tonicity of the medulla. Thanks for this! Great job!

[@ambikar2217]

+David Hinckley hey! can you please explain why the "the passive diffusion of water out of the descending limb does NOT change the tonicity of the medulla" occurs? this is what i was always confused about as well! thanks

[@david0hinckley]

+Ambika R Hey Ambika! So sorry this took me so long. Unfortunately I do not have a specific mechanistic answer for you; for me, the light bulb came on conceptually without needing to know the specifics. How that works is as follows: I had always approached the microenvironment of the loop of Henle as a closed system (my first mistake). Thus, it seemed to me that if I followed the movement of WATER out in the descending limb and then SOLUTES out in the descending limb, no net osmolarity would be gained or lost. The osmolarity in the tubule lumen vs the medulla would simply be inverse to each other. As water entered the medulla from the descending limb it would lower medullary osmolarity, and then when solutes entered the medulla from the ascending limb, this would raise the osmolarity to where it started from, NOT GREATER OSMOLARITY! However, what this video pointed out to me is that no certain part of the body is a completely closed system. Many, many transport systems exist that are SELECTIVE to certain molecules or substances, e.g. they transport some while leaving others behind. This is where I am ignorant of the mechanistic specifics but can still apply the concept. The peritubular capillaries run through the medulla, and substances can diffuse throughout the medulla. Hypothetically, the peritubular capillaries (or vasa recta, which are closer to the medullary loop of Henle if I am correct) could remove the water that leaves the descending limb but leave the solutes-- therefore leaving the osmolarity of the medulla unchanged by the "added" water. In this case, the water would be "passing through" rather than truly added to the environment in a way that affects the osmolarity. The system then makes sense to me: the solutes leaving the ascending limb permanently change the osmolarity and drive the countercurrent exchange system, while the water leaving the descending limb is simply subject to the forces created by the medullary osmolarity and do not affect medullary osmolarity. Therefore, the medullary osmolarity increases due to the continuous pumping of solutes out of the lumen and into the medulla. Does this make sense? Does anyone have a better mechanistic understanding of this?

[@medicalschool9028]

+David Hinckley maybe because its a dynamic system whereby at the same time water is moving out into the interstitium ur still pumping solute from the other side (from ascending limb to interstitium), the pump is like a battery recharging the system;

[@yvanliew5852]

@@ambikar2217Because there is vasa recta to absorb the water and prevent it from diluting the medullary interstitium (vasa recta as the countercurrent exchanger). Vasa recta helps to maintain the hyperosmolarity of medulla, but do note that it doesn't create the hyperosmolarity (it's the loop of Henle's job!).

[@alienware2149]

+David Hinckley hey...if your answer says so..then why does not the concentration of medulaary interstitum go on increasing throught the life?

[@sarafawzi5318]

why did you stop making videos ? they are awesome !!

[@MuhammadJunaidAshraf]

I have used many resources, watched a lot of videos but this video might be the BEST. Thank you Miss.

[@MrAmandeep42]

This is the best explanation on KZbin right now! Thank you

[@daniellereyes7320]

You sound like Garnet from Steven Universe! :D

[@alexpolanco3401]

For those questioning why doesn't the osmolarity of the interstitial fluid change when water leaves the descending limb .. The answer is more of an intuitive one. It's because the amount of water going into the interstitial fluid is pretty small compared to how much interstitial space there is and how much salt it has. It is like putting a few drops of water into a cup of salt .. Also, The water is quickly picked up by the capillaries surrounding the nephron so not much dilution will happen specially if the ascending limb keeps pumping more salt into the interstitial space.

[@malakds400]

Thank youu🤝

[@rq4740]

Only the second half of this argument is intelligible. If you make an approximation argument, then I can easily say that the salt being pumped from the ascending limb should not change the osmolarity, it’s like putting a few grains of salt in a gallon of water!

[@rq4740]

I’m now confident that both halves of your argument are wrong. The vasa recta do not play this role that you think they do. Equilibration is not a distinct step!! The salt pumps in ascending limb act to create a difference of 200 mOsm between the filtrate in the ascending limb and BOTH the interstitium and descending limb as the same functional compartment, because there is free movement of water between descending limb and interstitium. This also results in net water movement from the descending limb into the interstitium. I hope this makes sense to you

[@rq4740]

i.e. the pumps in the ascending limb pull water out of the descending limb by concentrating the interstitium, such that the pumps continue to act until they have raised the osmolarity IN BOTH COMPARTMENTS to the limiting difference

[@h.p.734]

@@rq4740 This Is the explanation I was looking for when I clicked this video. Ironically I found it in the comment section. Thank you!

[@sanaalsarayreh]

2 yrs later this is still relevant to myself! Oh my did these videos help me soooo muchhh!!! Thank you so much for sharing your knowledge. You did what my professor tried to do in two days, as I think they need to waste time and beat around the bush.

[@MrThomasAgf]

Yes. Thank you so much for this video, I’ve been looking for a visual and stepwise walkthrough. You’ve done very well, it’s very helpful.

[@andrewzhao444]

Why doesn't equilibrating change the concentration of the interstitial fluid?

[@jorgesanzana4262]

Andrew Zhao because the interstitial compartiment is too large in comparison to the tubular compartiment, in other words, you'd need a lot more water to lower the concentration of the interstitial fluid than the water that is reabsorbed on the descending branch

[@davidroesli]

Well it does change the concentration of the interstitial fluid, but not the osmolarity!!

[@benyamintee9909]

water won't dilute the ions because of the presense of Vasa Recta, which removes excess water.

[@aliceroxcullen98]

she/he should have mentioned that in the video.

[@thitipongpannawin7054]

Thank you

[@thankfullypositive]

Such a clear explanation & video, greatly appreciate it. I'm a bit confused by the osmolarity of the interstitial fluid doesn't remain the same after equilibration with the descending thin limb before fluid advance, can anyone out there clarify? For example, (@3:22) after the first equilibration, the interstitial osmolarity is arbitrarily set at all 400. However, for the next equilibrium exchange, (@3:44) we see Biomed set the interstitial fluid osmolarities not to all 400s, but to numbers matching the newly descending filtrate in the descending limb. Any clarification will be helpful.

[@liveranza]

Hannah Lee i have the same question. If in the interstitium the osmolarity is at 400 when urine fluid advances and the new urine has 300 mosm shouldn't H2O just rush out from the descending loop? How come its still 300 at both places? Anyone?

[@ibraheemalma]

6. The diffused water out of the descending segment is rapidly carried out by the vasa recta. Thus, this water does not dilute interstitium.

[@ibraheemalma]

@UCdlZ-I92ucqYoo2K8pP8JwQ الكلام العربي دخل عاللي بالانجلش فما فهمت الفقرة ممكن تصيغها ثاني كلها بالعربي او بالانجلش؟

[@caterinanatali3952]

you helped me a lot with my biology test, thank you for your increbibly clear presentation!

[@badrirouibi6755]

This video worth more than 2 hours of lecture. THANKSS

[@maryanne2025]

@ 3:12 would've appreciated if you had explained why is it that the Osmolarity doesn't change in the interstitial fluid between the ascending and descending loop, though water is leaving the descending loop into the interstitial fluid in between the ascending and descending loop? I thought perhaps the osmolarity of the interstitial fluid in between the limbs would also decrease? or is it because in the ascending limb, the solutes are being pumped out to to keep it at 400? If someone else can explain please do

[@Leonidasss123]

+Mary ann E There are vessels called Vasa recta in which the blood flows the opposite direction to the fluid in the loop and so when the water from the loop goes out to the intersticium its almost instantly ,,drained,, by the vasa recta due to its high osmolarity in it. So thats why the osmolarity in the intersticium doesnt change (it does, but its changed back immediately due to the water flowing to the vasa recta).

[@Suepearly95]

+Mary ann E HI. I had the same question, when I read Guyton it says 'Interstitial osmolarity is maintained at 400mOsm/L because of continued transport of ions out of the thick ascending Loop of Henle'. Hope this helps :)

[@drmjmrboh]

Hey Ruz, this is a very helpful video, I just wanted to ask a quick question about something that seemed strange to me: Why the numbers representing lets say the top two rows in the medullary interstitium keep returning to a value of 300mOsm/L? I'm not talking about the filtrate advancing in the lumen of the loop, but the interstitium.. After the equilibration at 3:17 for example the top value of the interestitium is 400mOsm/L, then the next time it shows up at 3:41, the top four values are back to 300mOsm/L? This part is the only thing unclear to me, as things in the interstitium are not supposed to move like in the loop? Thanks!

[@SamiK951]

Did you ever get an answer to this? This is confusing me big time

[@edthoreum7625]

perhaps this video is not perfect, but it visually helps us understand the loop of henle action?

[@icha_lim656]

i wanted to ask the same thing at all, why didn't the interstitial osmolarity stay the same as what the what descending limb just achieved

[@abbaskamil9016]

This is confusing me if someone know the answer please

[@hundle98]

i believe because it automatically transitions into equilibrium with the new filtrate coming down the descending limb, right before the ascending limb pumps out salt

[@cymaxo]

You are a legitimate superhero.

[@sincerelyernest]

Short simple and sweet. Great video. Thanks

[@nnlh413]

I only have one question if someone could help to answer. When the water diffuse out of the descending loop of Henle into the the surrounding salty medulla, why does it not change the osmolarity of the medullary intertistial fluid? I thought osmolarity is the measurement of the total number of solutes in a liquid solution, so when you increase the liquid solution, the osmolarity would be diluted, therefore decrease as more and more water enters the medulla?

[@sarvagyaverma9337]

From descending limb water is getting absorbed and from ascending limb electrolytes in almost equal proportion aas that of water are absorbed so osmolarity remains constant.

[@rq4740]

Other explanations here are wrong. The pumps in the ascending limb pull water out of the descending limb by concentrating the interstitium, such that the pumps continue to act until they have raised the osmolarity IN BOTH COMPARTMENTS to the limiting difference

[@PRAVEENKUMAR-yj6kk]

How at 3.49 you have showed interstitial fluid 's osmolarity as 300 at top ? earlier it was 400 .new filtrate is coming but the interstitial fluid is stationary na?or it is also moving?

[@usmansajid9888]

Same confusion here 🙄🙄

[@kulvirpandher4683]

Same question

[@AKapaTal]

You so brilliantly explained this, I'm thrilled at how well I understood this :)

[@tejasvisakhamuri1380]

There cannot be a better video explaining this. Thank you

[@leorio7416]

why does the osmolarity of the interstitial fluid changes when new filtrate enters the loop (300 osm.) ? @3:40

[@ahmetkeyan3346]

same questiion

[@bistdushejn]

same question here too

[@rq4740]

That segment is permeable to water so the tubular fluid and adjacent interstitium act like the same functional compartment w.r.t. osmolarity.

[@flightjarret4758]

5 minute video worth more than 50minute lecture.

[@S24W2]

Absolutely awesome video, thank you

[@Casualbystander]

This was absolutely incredible. Thank you so much oh my goodness. I have a midterm in two days and I have so much to go over lol. You made this exponentially easier than my textbook. Thank you.

[@AmonCastro]

She sounds like Sansa Stark

[@jackieheartseevee838]

An explanation behind the ''equilibrate'' would've been nice cause i'm still confused. What is the mechanism behind it?

[@DevilBesideYouu]

water moves out of the descending limb via osmosis :)

[@badranmohamed5772]

The descending and ascending limbs of the loop of Henle have different properties but the most important you should know about for the sack of your question is that the descending limb is highly permeable to water whereas the ascending limb is not. Because the descending limb is permeable to water, water can diffuse down its concentration gradient from an area of low solute concentration (the tubular lumen) to an area of high solute concentration (the renal interstitial fluid); this passive diffusion of water molecules is known as osmosis, and it occurs either transcellularly (through the epithelial cells of the descending limb) or paracellularly (through the tight junctions between the epithelial cells of the descending limb).

[@rq4740]

That segment is permeable to water so the tubular fluid and adjacent interstitium act like the same functional compartment w.r.t. osmolarity.

[@jamesmcclatchy7466]

One of the best tutorials I have seen. Well done

[@jasontong3918]

Thank you so much, these videos are excellent! Looking forward to seeing more!

[@revatibhand3572]

thank you so much for this!! this is honestly the best breakdown ive ever seen

[@jessicacard8805]

Great presentations...you've changed how I will teach these. I love the simplicity of your drawings and explanations. You really break it down to layman's terms. Thanks!!!!

[@leahsumin12]

I was so stressed about the countercurrent multiplier while just reading the textbook and now listening to your lecture, I feel great!!! thank you so much!

[@NadavGafni]

RUZ, great explanation!!!

[@zahirabernardi4357]

Thank you SO MUCH for this video! You won't imagine how much it helped me understand!

[@nilzadecatarina6916]

A round of applause for you! THANK YOU SO MUCH.

[@carlramponi91]

Dude. I don't think you could've made it any clearer... you're a godsend.

[@biomedsessions]

I'm glad that its helped you Carl 😊. Thank you for watching and commenting ^_^

[@quele5285]

Your 5:50 video explained the confusion I had in 1 hour lecture. Thank you!

[@soniia_aka3462]

Doing this in a levels and after several months I finally understand. Thank you 😊

[@MayaIslam12]

Perfect ! Your videos always save my life ! Thanks !

[@alyssatiambeng3]

this was a beautiful explanation, THANK YOU SO MUCH!!

[@krapsi1101]

I need more of these high quality videos, please make more of these! :)

[@ThanakritGu]

Best explanation out ther for counter current multiplication!

[@fallowme147]

Thank you so so much! I had my lecturer explain it to me twice and I was like ??????? What? But your video - i finally got it! You're an angel. Thank you for your work!

[@aliakram270]

Just amazing explanation!!! Thanks

[@shmoon64]

Best video to explain the countercurrent multiplication mechanism! Thank you so much! subscribed!!

[@audreyjacob6378]

This is outstanding. Well explained

[@abiekumar8139]

I watched other explanations of CC but yours really made sense thank you ❤

[@boredperson82]

This was amazing!!! A very lucid explanation!

[@awong8861]

I honestly did not understand the Loop of Henle and the whole renal medullary osmotic gradient until now THANK YOU!!

[@mathewhindi3163]

Very good explanation. Thanks!

[@baami8696]

Very informative and explicit video; cheers and keep up the good work!

[@nnlh413]

Thank you so much! Very very helpful! Best explanation of the countercurrent multiplication out there

[@juos11]

This is seriously a top notch explanation! Hope you make a comeback soon and make more videos! You have a talent for teaching, no doubt.

[@biomedsessions]

Thank you Juos :) I am hoping to make a comeback ^_^

[@richymt20]

Can’t believe I could grasp this confusing topic in just 20 minutes with this video, very thank u!

[@DietistaGabrieleFasulo]

Congratulations, extremely clear

[@pato20995]

Finally someone that explains it well, thanks

[@leinaessakalli9541]

AMAZING VIDEO!!! CONGRATS

[@bhimavarapushyamsundar5651]

u have explained it crystal clearly in this video and its the best.

[@RabehAlEnazy]

useful video, good job Rose

[@ifrafatima4211]

Oh my God it's amazing I just love this way of teaching Thank you thank you soooo much. I have been searching many many videos for last 1 year but couldn't find a video for better understanding and you made it May God bless you... Thank you soooo muchhhh 😍😍😍

[@VISHALBIOLOGY]

Excellent explanation!

[@chuckfukinnorris]

You seriously are the best !!! I hope you continue with these videos!

[@biomedsessions]

Oh wow, thank you Daniel! I'm glad they are useful to you. Yup there are more to come! ^_^

[@happyhormones_24]

Amazing explanation!

[@AC-nv5gm]

WONDERFUL. Thank you so much, Ruz.

[@angelinemerzier682]

This was very helpful! I was so confused in class! perfect explanation

[@zainabchaudary7477]

Please make more videos! You are an amazing teacher!!

[@papagenaa2972]

Studying for my next physiology exam, and this video is low key so helpful !

[@aarondavis176]

Well done, that was a huge help

[@nived8476]

Fantastic, thanks so much for the video!