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Video transcript

- [Voiceover] Have you ever tried to memorize all of the different types of anemias? If you have you know that that's a really, really hard thing to do. And that's because there are lots of different types of anemias. So to make the job a little bit easier for us, what they've done is they've split up all of the different types of anemias into three large categories. So just to catch up everybody to speed, anemia refers to when you have too few red blood cells. Too few red blood cells in the body. And like I said, there are three large groups of anemias. The first group. First group of anemias is called the microcytic anemias. The second group is called normocytic anemias. And the third group, the final group is called macrocytic anemias. And these three groups are split up according to the size of the red blood cell. So what do I mean by that? Well in microcytic anemia, you have micro, small, cytic cells. So you have small cells. Small red blood cells. Well how small is small? A normal red blood cell is anywhere between 80 to 100 micrometers cubed. So in microcytic anemia, you end up with red blood cells that are less than 80 micrometers cubed. The second group is a normocytic anemia. So normo means normal, cytic means cell. So these are red blood cells that are normal in size. So their size ranges anywhere between 80 to 100 micrometers cubed, okay? And finally, you have macrocytic anemia. So macro means large, cytic means cell so you have large red blood cells in this type of anemia. So these red blood cells are greater than 100 micrometers cubed. So these anemias are split up according to the size of the red blood cells. And it turns out that that has a lot to do with the cause of the anemia. With the underlying cause of the anemia. In this video, we're gonna talk about the microcytic anemia. So these guys right here. And I'm just gonna go ahead and put it all out there. I'm gonna tell you that all microcytic anemias, all of them are due to a problem. They're due to a problem in making, making hemoglobin, okay? So all microcytic anemias are due to a problem in making hemoglobin. And I guess I can't just say that. I should explain it a little bit, right? So let's start from the very beginning. What is hemoglobin? Well we do know that red blood cells, red blood cells are full of hemoglobin. Are full of hemoglobin. Okay and I know I'm spelling that a little funny. So red blood cells are full of hemoglobin and hemoglobin is actually what binds to the oxygen. So it's what gives a red blood cell the ability or the capacity to carry oxygen. So what is hemoglobin? Well I spelled it a little funny here to show you that hemoglobin has two main components. Two sub units, the first is heme. And the second as you may have guessed it is called globin. And globin is a polypeptide. So what that means is it's a chain of amino acids. And this chain isn't big enough or it isn't complex enough to be called a protein so it's called a polypeptide. And globin comes in two flavors inside hemoglobin. So there are two flavors of globin. The first is alphaglobin. And the second is called betaglobin. So these are the two main types of globin molecules inside hemoglobin. So the second component of hemoglobin is heme. And that itself has two sub units. Or two components. The first is protoporpherin. This is a picture of protoporpherin. And you can tell that it's a really complex molecule and it has this ring shape. It has this ring shape. And in the center there's this space. And that space is reserved for the second component of heme, which is iron. So in this space you're gonna find iron, okay? So in a nutshell that is the structure of hemoglobin, the different sub units to hemoglobin. But what does any of this have to do with binding oxygen? We said that hemoglobin is what binds the oxygen so where's the oxygen in this picture? Well it's actually found over here bound to the iron, okay? So iron serves a really, really important role in not only the structure but also the function of hemoglobin. So like I said, microcytic anemias, all the microcytic anemias are due to a problem in making hemoglobin. So what are some of the different ways in which you could end up with a problem in making hemoglobin? Well let's start from the bottom with the globin molecules. So if you had a problem with making globin, right? That would lead to a problem in making hemoglobin. And when we have a problem in making hemoglobin we end up with microcytic anemia. So those group of diseases in which you have a problem in making hemoglobin tend to be hereditary. They tend to be genetic. And they're referred to as the thalassemians. So these are a group of microcytic anemias in which you have due to a problem in making globin. Well moving up, what if we had a shortage of iron in the body? Okay. That would lead to a problem in making heme and hence a problem in making hemoglobin leading to microcytic anemia. Well that disease in which you have a shortage in iron leading to microcytic anemia is called iron deficiency anemia. I know very clever name, right? So iron deficiency anemia. Another very similar disease is anemia of chronic disease. And this is a type of microcytic anemia once again in which the body has enough iron, but for some reason or another, the red blood cells aren't able to access that iron to make hemoglobin. And so you end up with a microcytic anemia. Finally, if the body had a difficult time making protoporpherin, that would once again lead to a problem in making hemoglobin, subsequently causing a microcytic anemia. And that disease in which you have a problem in making protoporpherin is called cyteroblastic anemia. So these are different types of microcytic anemia. And we're gonna flesh out the details of these different anemias in later videos. But for right now it's good to know the different ways in which you could end up with a problem in making hemoglobin. So I guess the one thing I really haven't adressed to this point is why is it when you have a problem in making hemoglobin you end up with a microcytic anemia? Or an anemia where you have really small red blood cells. Well to explain that I'm gonna draw a normal red blood cell. And let's say this normal red blood cell has I don't know let's pick a random number like six. Let's say it has six hemoglobin molecules. So that's three, four, five, and six, okay? In a microcytic anemia, we would end up with a red blood cell that has too few hemoglobin molecules, right? Because we have a problem in making hemoglobin. So let's say instead of six we have four. Three, four hemoglobin molecules, okay? Well the body looks at this red blood cell and says that's a problem. We can't have that. We can't have this big old red blood cell with too few hemoglobin molecules inside it. And it says that if we can't have a good number of hemoglobin molecules inside each red blood cell, we should at least, at the very least try to get the concentration of hemoglobin molecules inside the red blood cells as close to normal as we can. And it does this by allowing the red blood cells to undergo essentially an extra, an extra division. Extra division. And this isn't exactly what happens but it's a really good way of thinking of it. So the red blood cell undergoes this extra division and you end up with two smaller red blood cells and each of them is gonna have two hemoglobin molecules inside. So as you can see from this picture, you end up with small red blood cells and each of those red blood cells has a fewer number of hemoglobin molecules inside. But as you can imagine, the concentration of hemoglobin inside these cells, because the cells are smaller, is closer to normal than with the cell over here. And so that's why, when you have a problem in making hemoglobin, you end up with a microcytic. A microcytic anemia. Or an anemia in which the red blood cells are much smaller than normal, okay? And like we discussed, these are the different types of microcytic anemia. The different ways in which you can end up with a problem in making hemoglobin.