Collecting Duct (CD): Atpase Pump

00:01 Now in the intercalated disc, one step further you must know that this hydrogen that is being pumped out into the lumen or the urine works to the hydrogen-potassium pump. It all begins with the sodium-potassium pump on the basolateral membrane. Now be careful there all that I wish for you to do technically is to work with that hydrogen. One other piece of news that I wish to give to you here is that hydrogen that is being pumped out. Do you see it now versus NH4. That is ammonium, and that is an incredibly important buffer actually most to be hydrogen is buffered through ammonia. Do you remember where ammonia was produced and synthesized? Way back in the proximal convoluted tubule. I told you at that time that we would see here in terms of its buffering effect with hydrogen. So ammonia, NH3 when it takes up hydrogen is now called ammonium or you have titrated acid and that is going to be a phosphate.

01:00 So whenever you have heard in physiology as titrated acid, this then means that this is then going to pick up hydrogen in the hopes of trying to buffer that hydrogen and tell me about that bicarb is this reabsorbed, is it newly synthesized? It is newly synthesized.

01:18 Where every single cell goes through glycolysis, doesn't it? As human beings, we have aerobic glycolysis hopefully majority of the time and so therefore as you go through TCA cycle, take a look at the very left there, you see that carbon dioxide, where is it coming from? TCA cycle. You give outside carbon dioxide. All of this is going to help you contribute to the forward movement and production of hydrogen and bicarb. That hydrogen potassium pump located in the collecting duct , primary site for hydrogen to get rid of. Potassium technically is reabsorbed, but now this is titratable acid. Please know. Pay attention that phosphate to you should mean titratable acidity. Now that is more technical. It is more of a research thing, but know the name, memorize it, please. Is this majority of how hydrogen is buffered? No, no, no. It is one of the ways. This is the majority of how hydrogen is buffered.

02:18 Look and highlight in your head NH3. That is ammonia. It will then pick up the hydrogen and end up forming ammonium and we talked about ammonia in greater detail earlier. We talk about ammonia having a alkaline nature. We talked about the struvite staghorn stone with magnesium ammonia phosphate. Talked about asterixis as well, with liver damage.

02:39 Both titratable acids in ammonia, acidifies the urine. Bicarb is synthesized and reabsorbed into the ECF. This is the primary site for regeneration of a bicarb if need be.