Countercurrent Multiplier Mechanism of Urine Concentration in Kidney | Countercurrent Mechanism

[@solace8773]

Why does CCM stop when the inner medullary interstitial osmolarity reaches 1200 mOsm/L (or 2400 in camels) instead of going on continuously to result in even greater osmolarity?

[@NonstopNeuron]

Look at it this way: A dilute filtrate is continuously entering from the top of the descending limb. It keeps getting concerned as it descends. The deeper it goes the more concerned it gets. Based on depth in humans, it reaches up to 1200. Then it starts ascending, and the concentration starts falling. I hope it helps.

[@solace8773]

@@NonstopNeuron I understand that, but when the fluid at the thin descending limb reaches 1200 osmolarity, wouldn't the thick ascending limb continue to pump out solutes to make the surrounding interstitium even more concentrated than 1200 mOsm? How does the loop of Henle length affect this process?

[@NonstopNeuron]

No. Because simultaneously dilute fluid from the top keeps moving down and keeps diluting the fluid on the lower side.

[@NonstopNeuron]

Both things are happening simultaneously. Concentration by ascending limb, and dilution by fluid from top. Final concentration at any level depends on the equilibrium of two.

[@solace8773]

​@@NonstopNeuron Thanks for the explanation!

[@HappyDsp189]

10:50 but diluted fluid in top of the ascending loop right?

[@adrianpurcea8453]

Thank you very much for this video!❤❤. I have physiology exam (cardiovascular, respiratory and urinary systems) on Monday and urinary lecture was the last! You've really saved me!🎉

[@NonstopNeuron]

Most welcome

[@periand.4897]

One small critique - in the beginning when reabsorption is shown, with solutes moving from the tubule lumen to the interstitium, the renal tubule cells should have their luminal (apical) membranes facing the lumen, not the interstitium. You can tell its presented "backwards" because tight junctions are apical (which indicates the luminal membrane).

[@NonstopNeuron]

Oops... How did I miss that...! Thanks for pointing it out. Will note it down for future updates.

[@periand.4897]

@@NonstopNeuron I think your video does a great job at presenting one of the most challenging concepts of renal physiology, esp. for undergrads.

[@muqtarjamaegal6071]

Waiting long time this is treasure to me self study 📖 is better than what ever✋️ ❤

[@nerdyalien9906]

Very underrated

[@Hera_070]

Thank you so much for the great explanation. Please Ma'am When you say equilibrium does that mean the values of Osmolality must be exactly the same?? I thought it meant fluid movement is occuring at the same rate and the conc. in mosm. Doesn't have to be the same??

[@LimenhWale]

Thank you mis.

[@SKANDA295]

Sir If possible Please explain Route of drug administration theory+ objective wise and Enzyme induction and inhibition topic....

[@anuuu6901]

Does counter current multiplier mechanism occurs only in juxtamedullary nephrons

[@NonstopNeuron]

No. But for the inner medulla, it is more important.

[@aliakgun3237]

at minute 8 must the equilibrium be 350.... why is it 400 mosm/l

[@NonstopNeuron]

Please don't isolate any step from others. If you do so, the confusion is bound to happen. To give you a conceptual model, I have to mention them one by one. There is no other way of explaining. But in reality everything is happening simultaneously.

[@aliakgun3237]

thank you very much

[@Hera_070]

Thank you so much for the great explanation. Please Ma'am, When you say equilibrium does that mean the values of Osmolality must be exactly the same?? I thought it meant fluid movement is occuring at the same rate and the conc. in mosm. Doesn't have to be the same??