all right. So here we have our membrane transport map of our lesson. And so, so far we've explored are left branch with molecular transport. And we've talked a lot about passive transport, differentiating simple versus facilitated. And in our last lesson video, we talked about the differences between carrier slash transporters and poor and slash channels. And so in this video, we're going to talk about where we're headed next, which is talking about very specific types of carrier slash transporters. And we're going to talk about the Aretha, recite glucose Uni Porter glute one and are very next video. And then after that, we'll talk about the ARY throw site chloride bicarbonate, Anti Porter. Then after that, we'll zoom out and talk about some specific types of porn slash channels. And so this year concludes this video and I'll see you guys in our next video where we'll talk about theory. Throw site glucose unit. Porter Glue one. See you guys. There

So a classic biological example of facilitated passive transport are a re throw site or red blood cell glucose transporters called glute one. And so glute one because it is a transporter, we already know that it must undergo confirmation all changes in order to transport a molecule across the membrane. And that is exactly what glute one does. So glute one confirmation Aly changes as it transports glucose down its concentration Grady int across the membrane and glute. One is able to do this as a uni porter, which, you might recall, just means that it transports one molecule at a time in a specific direction. Now, due to glucose metabolism inside of cells, glucose is constantly being broken down and used to create energy. And so glucose concentration inside of cells generally is going to be kept relatively low with respect to the blood glucose concentration. And so if we take a look at our image down below right here, notice we're showing you the glute one uni porter. And of course, we're zooming into the plasma membrane of the R E throw site or the red blood cell. And in the plasma membrane of the Aretha Row site or red blood cell. That's where we can find this glute one unique porter. And so notice that on the inside of the cell, which we have marked with the yellow background, there is a lower concentration of glucose again due to glucose metabolism inside of cells. That glucose concentration is kept low, as we indicate here. And, of course, on the outside of the cell. Up here there is a higher concentration of glucose and the blood. And so, because again glute one is a transporter, we know that it's going to bind to one of the glucose molecules and then undergo a confirmation. Allchin change here to allow the glucose molecule to be released to the inside of the cell. And, of course, once it releases that glucose molecule to the inside of the cell, it can revert back to its original position, where it can again continue this process and take in another glucose molecule. Now what's also important to note is that there are actually several different types of glucose transporters that exist, and they exist in different tissues with varied, functional roles. And so as we move forward in our course, we will talk about other types of glucose transporters as well. Here in this video, we talked about the glute one transporter. And so in this table you can see the type of glucose transporter in this column, the tissue that the glucose transporter is expressed in this column and the biological role that the transporters have in those tissues. And so the glute one transporter notice that it is actually ubiquitously expressed. And so it is going to be expressed pretty much everywhere in all cell types, including a re throw sites, our red blood cells and its biological role is for basil glucose uptake, essentially just bringing in glucose into the cell now moving forward in our course later, Uh, in our course, we'll also talk about other glucose transporters, like glued to and glute four. And so here we're just introducing that there are other glucose transporters and there are, of course, more than just glued to and glue before, but moving forward, glued to and glute four are the ones that were specifically going to talk about later in our course. And so don't worry too much about the tissue expression and the biological roles. Uh, this is just here for context, and we will revisit glued to include four again later in our course. For now, what I want you guys to see is that glute One is a classic example of facilitated passive transport. And it is found in a wreath Oocytes, a Zaid Glucose Uni porter. And so this year concludes our lesson on the Aretha Oocyte glucose unit Porter glute one and will be able to get a little bit of practice in our next video. So I'll see you guys there.

so another classic example of facilitated passive transport are a re throw site or red blood cell chloride bicarbonate anti porters. Now, before we talk Maura about thes chloride bicarbonate anti porters, I first want to point out that this image that we have down here should look familiar to you guys from our previous lesson videos. Specifically, where we talked about hemoglobin is binding activity in the tissues versus in the lungs. And so if this image does not look familiar to you guys, be sure it and go to go back and check out those older lesson videos before you continue here. Now that being said, there are a few things that we're going to review in this video from those older lesson videos. And so the first thing that I want you guys to recall from those older lesson videos is that CO two or carbon dioxide that's produced by our response airing tissues is going to defuse into our A re throw sites. And on the inside of our re throw sites is where we can find an enzyme called carbonic and hydrates that will convert the CO two and water into the bicarbonate, and I on that we see here h c 03 minus, which plays a really, really big role in the chloride bicarbonate anti porter that we're going to introduce here shortly. And so let's take a look at our image down below to remind ourselves of a few things. And so, first, I want to remind you that the entire left hand side of the image over here is pretty much dedicated to our blood near the tissues. And so here in the middle, on the left hand side, we can label this as being near the tissues. And, of course, the entire right hand side of the image all the way over here is dedicated to our blood near the lungs. And so over here on the right hand side, we can label this as near the lungs and so you can see that this dotted black line that we see here is really separating what we want to focus on and separate the blood near the tissues versus the blood near the lungs. And so, as we mentioned up above our response, Irish tissues are producing lots and lots of CO two, and so there's a high concentration of Co two in our tissues. And, of course, the CO two is going to defuse out of the tissues and into the blood and make its way into our or re throw site, which is our red blood cell right here and once the co two is inside of our re throw sites. That's where the enzyme carbonic and hydrates can convert the CO two and water into carbonic acid, which will disassociate in, break apart into the car by carbon it an eye on and ah, hydrogen ion And, of course, the bicarbonate. And I in here is going to play a really big role in the chloride bicarbonate anti porter, which is this blue structure that we see right here that will talk about here very shortly. And so now that we've reminded ourselves that by carbon it is definitely found in our blood, we can now focus our attention on chloride, bicarbonate, anti porters and so chloride bicarbonate. Anti porters are going to passively transport as their name implies chloride and bicarbonate in opposite directions. And of course, we know that that's exactly what anti porters do. They take two molecules and they transport them across the membrane in opposite directions. And so, as the chloride is being transported and one direction and the bicarbonate is being transported in the opposite direction across the membrane, this shift of chloride and bicarbonate is commonly referred to as just the chloride shift, even though by carbon it still plays a really big role in this process. And so again, this chloride shift is really just referring to the phenomenon of chloride and bicarbonate exchange near the tissues and near the lungs, and the way that this chloride bicarbonate exchange works is going to be different near the tissues and near the lungs. But we'll talk more about exactly how the chloride shift works and more detail once we get to this section down below. But first I wanna let you guys know that the chloride and ion, uh, really is just acting as a counter ion toe. Help balance the charge across the membrane when the bicarbonate is pumped across the membrane. And really, it's the bicarbonate that has the most important functions off the chloride shift. And so the bicarbonate really has two roles. First, it helps, uh, it acts as a buffer to maintain blood. PH, which is important for maintaining the structure of enzymes in our blood. But also the chloride shift and the bicarbonate shifting also has another MAWR important role, which is that it increases the blood's capacity to transport carbon dioxide from the tissues to the lungs. And so, really, this increase in the blood's capacity to carry carbon dioxide is really the main function that the chloride shift provides. And so now let's focus mawr in on How exactly does this chloride shift work? So we can help clarify some of the ideas that we've talked about? And again, the chloride shift is going toe work differently when it's near the tissues and when it's near the lungs. And so when it's near the tissues, as we mentioned over here already by carbon it, an ion is going to be produced, and so there's gonna be a high concentration of bicarbonate and ion inside of the cell near the tissues, and so the high concentration of by carbon it is going to defuse down its concentration Grady int and make its way to the outside of the cell. And so you can see that the bicarbonate and I in here again, which is in high concentration on the inside of the cell, near the tissues is going to defuse to the outside of the cell here, uh, near the tissues. And it's gonna do that via the chloride bicarbonate anti porter, which is again, this blue structure that we see right here. And as the bicarbonate gets pumped out of the cell, the chloride an ion is being pumped into the cell in a 1 to ratio. And so, uh, near the lungs, this all works a little bit differently. And so what you can see is near the lungs. There's actually a low concentration of CO two, which is the opposite of what we have near the tissues. And so what happens is this reaction that's catalyzed by carbonic and hydrates is going in the opposite direction as it was here. And so you can see that the by carbon it is actually being converted to co two. And the co two is making its way to the lungs where it can be exhaled. And so what needs to happen near the lungs is that the bicarbonate an ion is actually going to be transported into the ary throw site. where it can be converted into the CO two and then ultimately exhaled. And as the bicarbonate gets shifted into the cell near the lungs, the chloride, an eye on that was originally shifted into the cell is now going to be shifted back out of the cell, reversing essentially what happened near the tissues. And so this can happen in a cycle. So essentially, what happens near the lungs is pretty much the complete opposite of what happens in the tissues. The opposite events occurred, and so, just to be clear on this idea, near the tissues by carbon, it leaves the cell and chloride comes into the cell. But near the lungs by carbon it is going into the cell, whereas the chloride ion ion is leaving the cell once again. And so really, this here concludes our introduction to the Aretha recite chloride bicarbonate, anti porter and the chloride shift, and we'll be able to get some practice applying these concepts in our next couple of videos. So I'll see you guys there