Hemoglobin Binding in Tissues & Lungs

in this video, we're going to begin our discussion on hemoglobin binding in the tissues and in the lungs. And so at this point in our course, we already know that hemoglobin combined to oxygen, however, which you may not have known is that hemoglobin can also bind to carbon dioxide and protons. And so this leads us directly into what's known as the boar effect, which were actually going to talk about in a lot more detail later in our course. But for now, I can tell you that the Boer Effect just describes the effect of the concentration of carbon dioxide or CO two. And it describes the effect of pH. Or, in other words, it describes the effect of hydrogen ion. Concentration on hemoglobin is binding and release of oxygen. And so it's important to note that under low oxygen conditions, hemoglobin is actually going to release its oxygen. But when hemoglobin releases its oxygen, it's actually capable of binding and transporting both carbon dioxide and protons. And so when hemoglobin binds carbon dioxide, we're going to refer to it is just hbc 02 and when hemoglobin binds protons, we're going to refer to it as HB Plus and So Co two and hydrogen ions are both going to act as hetero tropic Allah host Eric inhibitors to hemoglobin, oxygen binding activity. And so recall from our previous lesson videos. Hetero is just referring to the fact that carbon dioxide and protons are different than oxygen. And so these are the Alistair defectors, and the Alistair defectors are different than the lie gone, and that's why it's hetero. And, of course, we know that inhibitors are going to decrease the activity. And so both CO two and protons are going to decrease hemoglobin oxygen binding activity. And so what this means is that both carbonation and protein ation of hemoglobin are going to stabilize hemoglobin T state, which is the 10th state. And of course, the T State binds like and inefficiently so. Hemoglobin. When it's, uh when hemoglobin T state is being stabilized, it's going to cause hemoglobin to release its oxygen. And so, essentially, what we're saying here is that both carbon dioxide and protons are going to cause hemoglobin to release its oxygen. And so if we take a look at our image down below notice over here on the left hand side, What we have is hemoglobin s T state. And when hemoglobin is in the T state like this, essentially, uh, it can be bound to carbon dioxide as well as protons. Now, depending on whether where specifically focusing on carbon dioxide or protons being bound, we're going to refer to this form of hemoglobin as either H B Co two or HB H H B plus, and so notice that when hemoglobin is in its TI state, it's going to be releasing its oxygen now. Specifically, these conditions here, as we can see, are going to exist in the tissues. And so in the lungs. It turns out that, uh, the opposite is reaction here is going to occur. And so in the lungs, uh, hemoglobin is going to be present, mostly in its are state. And so here we have the our state hemoglobin, which we know has a high affinity for its like gin. And so when it's in its our state, it's going to be binding toe oxygen as UH, h b 02 And then, of course, when it's in its our state, it's going to have to release hydrogen ions or CO. Two. So you can pretty much think of this as hemoglobin has an option. It can either bind carbon dioxide in protons, but release oxygen. Or it can bind oxygen and release protons and CO two. And so, uh, as we move forward in our course, we're going to talk about the exact conditions, uh, in the tissues that allow for the T state to be stabilized. A sui see here. And we'll talk about the exact conditions in the lungs that allow for the our state of hemoglobin to be stabilized like we see over here. And so this concludes. Our introduction to hemoglobin is binding to carbon dioxide and protons, and later in our course will be ableto focus, even mawr on this particular binding. So I'll see you guys in our next video.

in this video, we're going to talk about the exact conditions in our muscle tissues that allows for hemoglobin to release oxygen in our tissues. And so, first, we need to note that our muscle tissues are constantly contracting and respond hiring and recall from your previous biology courses that cellular respiration allows our muscle tissues to acquire the energy that they need for a muscle contraction. However, cellular respiration also consumes Ah, lot of oxygen. And so what we're saying here is that in our muscle tissues, oxygen is constantly being consumed and depleted through cellular respiration, leading to a relatively low partial pressure of oxygen in the tissues right around a value of about 20 tours, which is very low, especially in comparison to the partial pressure of oxygen in our lungs, which is five times greater at a value of about tours. And so again, what we're saying here is that in our muscle tissues, oxygen is relatively low now, of course, in our response airing muscle tissues, cellular respiration is going to lead to lots of C production, carbon dioxide production produced by metabolism, and so in our muscle tissues we're going to have quite a high concentration of co two. And so really, this These are the conditions in our muscle tissues that allow for us to get the background that we need to understand. The next five steps that we have down below that lead to hemoglobin is release of oxygen in the tissues. And so, with step number one here, we're going to start off with the high concentration of CO two and our muscle tissues. And so the concentrations of CO two are so high in our muscle tissues that these high amounts of CO two produced by are responding tissues is going to diffuse out of our muscle tissues into the capillaries and into our red blood cells or are RBC s for short and so down below in our image right here. Notice On the far left, what we have is our muscle tissues. Here you can see we have a image of a bicep and noticed that the number one right here also corresponds with the number one up above. So, uh, in our muscle tissues, there's quite a high concentration of co two like we set up above and the high amounts of CO two is going to diffuse into the cap players and into our red blood cell. So all of this co two here is gonna defuse out of the muscle tissues and into the red blood cell, which is, uh, actually represented by this red box right here. Now, way down below. Over here, we also have another representation of, um the steps up above that lead to hemoglobin, release of oxygen in the tissues. So if we take a look at this image down below, notice that we're zooming in specifically on the area of the blood by the tissues and in this image over here on the far left, what we have our our muscle tissues. And then over here, the rest of the image is representing our blood. Cavalleri. And of course, this red circle right here represents the exact red blood cell. And so what you'll notice is that in our muscle tissues, there's quite a high concentration of co two indicated by number one right here, which corresponds with the number one up above as well. And so there's so much co two being produced by our muscle tissues that it's going to diffuse out of our muscle tissues into the blood capillary and ultimately make its way into the red blood cell. So that leads us directly to step number two here. And so inside of our red blood cells, there's actually an enzyme known as carbonic and hydrates, and so carbonic and hydrates. Catalyze is a reaction. Um, where CO two can react with water to form carbonic acid, which is relatively acidic and breaks up into bicarbonate and a proton. And so you can see that the number two right here corresponds with the number two and you can see that the carbonic and hydrates enzyme inside of the red blood cell here is catalyzing a reaction where CO two can react with water to produce carbonic acid h two c 03 which has a PK of 6.35 and is relatively acidic. So it's going to break up into its conjugate base bicarbonate and a proton right here. And so if we take a look down below at our image over here, notice that the number two right here carbonic and hydrates is showing the same reaction being catalyzed where the co two is reacting with water to form carbonic acid, which is going to break up into its conjugate base bicarbonate and a proton. And so there is so much, uh, CO two being produced in the tissues that when it diffuses into the red blood cell, there's also going to be quite a high concentration of CO two in the red blood cell. And, of course, uh, the high concentration of CO two is going to cause this equilibrium right here by lush at liaise principle to compensate for the high Co two by shifting to the right towards the production of hydrogen ions. And so notice that with step number three what we're saying is that this equilibrium shift towards hydrogen ion production due to the high concentrations of CO two in the muscle tissues, along with the fact that muscle tissues produce lactic acid, an idea that will talk more about later in our course together, this lactic acid production and the equilibrium shift towards H plus leads to an increased concentration of H plus in our tissues. And of course, an increased concentration of H plus we know corresponds with a decrease in the pH from a ph of about 7.4 down to a pH of about 7.2 in the tissues, which is actually relatively acidic in comparison to the blood ph of 7.4, which is where the blood pH is normally at when it's not near the lungs or near the tissues. And so we have the number three right here to correspond with the number three down below to show that there is indeed a pH decrease down to 7.2, and we have that same number three down below right here, showing the equilibrium shift to the right towards hydrogen ion production due to the high concentrations of CO two. And so because H plus is being increased, the blood pH in the tissues is being decreased down to a value of about 7.2 and so moving on to our step number four here. What we need to recall is that near the tissues, him a global is actually going to bind carbon dioxide and bind protons. And the reason for this is because in the tissues again there's a high concentration of CO two lots and lots of CO two, and there's an equilibrium shift towards H plus, so H plus is being increased. So we have lots of H plus and lots of CO two in the tissues. And there's so much co two and H plus in the tissues that hemoglobin is just bound to bind to all of this co two and H plus when it's near the tissues. And, of course, we know from our last lesson video that CO two and H plus act as hetero tropic Alice Terek inhibitors to hemoglobin, oxygen binding. So when hemoglobin binds to CO two and H plus in the tissues, it's going to cause, uh, hemoglobin to release. Uh, it's oxygen. And so, essentially, what we're saying here is that in the tissues hemoglobin is going to go from being in, it's our state when it's bound to locks of oxygen, and it's going to shift into its T state in the tissues. And so when it's in its T shaped T state, it's going to bind co two and hydrogen ions while releasing oxygen. And so if we take a look down below at our step number four, you'll see our step Number four is right. Uh, here. And so what you can see is that upon arrival to the tissues. Hemoglobin is bound to oxygen in its our state, and so we have the our state hemoglobin here bound toe oxygen. But as soon as hemoglobin encounters the high concentration of hydrogen ion and the high concentrations of CO. Two again, there's so much co two and so much h plus that it's bound to react with the hemoglobin here, and it's bound to bind to the hemoglobin. All of the CO two and H Plus is bound to bind to the hemoglobin, which is going to stabilize the tea state of the hemoglobin. And, of course, the T state of the hemoglobin has a lowered affinity for oxygen. So it's going to release the oxygen. And that's exactly what we have here is released oxygen now and step number five. What we need to recall from our previous lesson videos is that myoglobin abbreviated as M B. Is, uh, its function is, um, in the tissue. So notice that myoglobin is over here in brown, and it's correlating with step number five here, and so myoglobin recall from our previous lesson Videos has a smaller K D and therefore a stronger oxygen affinity than hemoglobin and So this means that myoglobin, when it's present in the tissues like this, it's going to facilitate oxygen diffusion into the tissues. And so, essentially, what we're saying is hemoglobin is going to release this oxygen, and then this oxygen diffusion into the tissues here like this, is being facilitated by myoglobin high affinity for oxygen. And so again, over here on the left, we have this circulatory system where we can see that the blood ph in the tissues is 7.2. Um, and the blood pH at normal levels is around 7.4, and then the blood pH in the lungs is around 7.6. And so now that we can understand better, How exactly? These five steps right here lead to hemoglobin is release of oxygen in the tissues, and our next video will be able to talk about how hemoglobin is able to bind oxygen in the lungs. So I'll see you guys in our next video

So now that we know that hemoglobin releases oxygen in our muscle tissues in this video, we're going to talk about the exact conditions in our lungs that allows hemoglobin to bind oxygen in our lungs. And so, really, these conditions in our lungs are going to be pretty much the exact opposite of the conditions in our tissues. And so what we need to realize about our lungs is that we're constantly and repetitive Lee breathing in and out. And so we're constantly inhaling lots and lots and lots of oxygen, meaning that in our lungs were going to have a relatively high partial pressure of oxygen right around a value of about 100 tours, which is again fairly high, considering that the partial pressure of oxygen in our muscle tissues is on Lee about tours. And so we also need to realize that in our lungs, with every breath that we breathe out, we are exhaling lots and lots of carbon dioxide or CO two, meaning that we're going to have a relatively low concentration of CO two in our lungs. And so what you'll note is that these here are the conditions that are required in our lungs to understand the next five steps that allows hemoglobin toe bind oxygen in the lungs. And so, just like we started our last story with concentration of CO two in this video, we're also going to start with concentration of CO two. And, of course, in our lungs. We know that there's a low concentration of co two do two x elation. And so if we take a look at our image down below, we can better understand thes steps that we have and so notice that we're zooming in on the bloodstream by the lungs. And so over here on the far right, what we have is our lungs. And then, of course, we have our bloodstream, our blood capillary over here on the left with our red blood cell here in this circle. And so one thing to note is that this equation that we talked about in our last lesson video right here is actually being flipped. And that's actually OK because we have these equilibrium arrows, and it's totally possible for these reactions to go in the Ford and reverse direction. And so we did flip this reaction here, so keep that in mind. And so what's important to note is that in our lungs were constantly exhaling co two. So there's going to be a very, very low concentrations of co two, and this low concentration of CO two is going to translate backwards here into our red blood cells. So we're going to have a very low concentration of CO two here in our red blood cell. And so if we have a low concentration of CO two, of course, by the shot liaise principle, this equilibrium here, controlled by carbonic and hydrates, is going to compensate for this decrease in CO two by shifting to the right, and so it's going to be shifting towards the production of C 02 And so that is exactly our number one up above. So the number one corresponds with this equilibrium shift. And of course, the Low Co two and our lungs is going to cause the reaction equilibrium to shift towards co two production. And, of course, if it's shifting towards CO two production, that means that the concentration of hydrogen ions is going to decrease. And so if we decrease our concentration of hydrogen ions, of course that's going to correspond with an increase in the pH up to about a value of 7.6 in the lungs. And so notice over here. What we're saying is that the pH in the lungs, the blood ph in the lungs is going to be right around a value of 7.6, which is slightly basic in comparison to the blood pH the normal blood ph of 7.4 as well as the blood pH in the tissues, which we already know slightly acidic at 7.2. And so again, what we need to realize here is that in our second step, this low concentration of CO two in our lungs, again via X elation, is going to cause the CO two diffusion into the lungs. And so if we take a look at our image down below again, we have a very, very low concentration of CEO to here. And so, uh, recall that the way that diffusion works is that it goes from high to low concentration. And so if we have a low concentration here, that must mean that we must have a higher concentration of CO two out here, and so that is going to cause CO two to defuse into the lungs. And that is exactly how we have step number two right here, which corresponds with again step number two here, diffusion of CO two into the lungs. And that allows us to breathe out all of the CO two in our lungs, which is going toe leave our bodies and go into the atmosphere. And so this leads us to our third step right here and in our third step. What we need to realize is that in our lungs were also constantly inhaling lots and lots of oxygen. So we have a very high concentration of oxygen in our lungs. And so here what we can say is that we have high oxygen in our lungs via inhalation. Um and this is going to cause oxygen diffusion into the capillaries and into our red blood cells or are RBC s for short. And so again, the way that diffusion works is it goes from a high concentration to a low concentration and upon arrival to the lungs, hemoglobin is going to be in its de oxygenated t state, and so that means that it's not going to be bound toe oxygen. And so it's gonna have relatively low oxygen in the red blood cell and again high oxygen in our lungs with every inhalation. And so it diffuses from high to low. And so, uh, you can see that the number three right here corresponds with oxygen being diffused into the capital areas into our red blood cells. And so that leads us to step number four. Which, of course, we know that when hemoglobin is near the lungs, hemoglobin is going to bind all of that oxygen that's present and available pretty much endlessly with every single breath that we take. And, of course, if it binds onto the oxygen, that means that the our state is going to dominate. And when hemoglobin is in the our state, it's going to release, Ah, carbon dioxide and hydrogen ion. So essentially, what we're saying is that near the lungs, hemoglobin is going to transition from its T state to its our state. And, of course, in its our state, it's going to have a high affinity for oxygen, and it's going to be bound to oxygen. And so, in step number five, all of this oxygenated hemoglobin is ready to deliver oxygen to the tissues, and so you can see that in the lungs, hemoglobin becomes oxygenated, and then eventually it will make its way down to the tissues where it can deliver that oxygen and then go back to the lungs to acquire oxygen again and then go back to deliver oxygen. And this is a constant cycle that allows hemoglobin to be an excellent oxygen deliver and transporter. And so one thing to note here about the lungs is that myoglobin does not come into play because myoglobin is really only going to be significant in the tissues and not in the lungs. And so this here concludes our lesson as Thio. Why exactly? Hemoglobin binds oxygen in the lungs, and we'll be able to get some practice utilizing all of these concepts as we move forward in our course. So I'll see you guys in our next video.