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Hypertension effects on the blood vessels

Learn about how hypertension can cause damage to the large/middle sized arteries as well as the small arteries and arterioles. Rishi is a pediatric infectious disease physician and works at Khan Academy. Created by Rishi Desai.

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Video transcript

Now, we've talked about hypertension, and you know that it means that you have high blood pressure. So the next logical thing to think about is why is that bad? Why is it a problem to have high blood pressure? And I like to think about high blood pressure from two different perspectives-- one would be the perspective of the heart, and the other is the perspective of the blood vessels. And so here you can almost divide it up as the thing that's making the pressure or generating the pressure, which is the heart, and the thing that's receiving the pressure. So generating versus receiving pressure, and each of these two areas has some serious consequences for the body. So let's just divide it up here. Let's just draw a dashed line, divide up our screen, and we'll talk about both areas. So let's start with the receiving pressure side. So we have the large and middle sized arteries-- and specifically I mean arteries that are between, let's say, 25 millimeters in diameter all the way down to about one millimeter in diameter. So primarily these are the vessels that are going to get blood from the heart to the different organs that it needs to get to. And then you of course have the small arteries and arterioles. And these are going to be at the high end. They're going to be one millimeter. But they're going to go all the way down and get smaller and smaller to about 0.01 millimeters, so about 1/100 of the size. They're very tiny. And these are receiving pressure. Both of them are receiving pressure. These I'll draw as-- I'll leave the drawing up above, and these are kind of very, very narrow ones, right? So both of them are receiving the pressure, and they're going to have problems. So for example, if you have, let's say, a large or middle artery that is-- let me draw it in a different color. Let's say here it's very elastic-- over time if you keep exposing this elastic vessel or tube to high pressures, over time what would happen is this becomes very firm, like a pipe. So that's one change. And in fact, that change from being elastic to firm, we call that arteriosclerosis. I'll write that in white-- arteriosclerosis. And in fact, a very similar thing happens on the other side with the small arteries and arterioles. They also have very similar kind of change. They can go from being very elastic-- I'm trying to draw it so it's got some springiness. That's obviously kind of tricky to draw. These become very firm as well over time, and they lose that elasticity. And when it happens in the small arteries or arterioles, we call that arteriolosclerosis-- a very similar word, but slightly different-- arteriolo-- an extra L and an O-- sclerosis. So this is the difference, right? They're very similar things, kind of similar processes, but one is in the smaller arteries and one is in the larger and middle sized arteries. So this is one of the things that can happen when you have lots of high blood pressure constantly exposed to the vessels. They can become firm. OK, going back to the large and middle arteries, you also can have a situation-- I'll draw it here-- where you have an artery, let's say-- actually, let me write what it is first. You can have an aneurysm. And an aneurysm is where you have a vessel-- let's say this is my vessel, and it's taking blood through it. So blood is going through it. And because of the constant blood pressure that's going through this vessel, the wall starts to get weak. So at one spot, it starts to get weak. Let's say right here instead of being like that, it starts to look like this. And you get this little area of weakness. I'll try to draw it like that. And because it's weak, the blood will start going, and hitting, and bouncing off the walls, and making it a little bit bigger. So it looks like that. And over time, it might do this. It might become a big sack. And that's an aneurysm. And actually that aneurysm, if it's a sack of blood, can actually burst and break. And that blood can spill out, and we call that hemorrhage. So you can actually have an aneurysm because of a weak vessel wall. Now, looking at the small arteries or arterioles, you can also have, not necessarily aneurysms in the same way, but you can have breaking or hemorrhage. And here I want to show you or remind you that these vessels, these tiny ones anyway, they're usually not sitting out there on their own. They're usually within an organ. So this tiny vessel-- remember, it's one millimeter to a hundredth of a millimeter. So it's actually sitting inside of a kidney or sitting inside of an eye. And so these organs have inside of them these arterioles and small arteries. And so when they're in that situation, if you have a break, let's say-- actually, let me rewrite this slightly differently. If you have a break in the vessel, we actually get organ damage. So this could be because the vessel literally breaks right here and blood spills out. And it could also be because these tiny vessels are necessary to make the organ work. For example, the kidneys require that these small arteries and arterioles are working properly. And if they're not, you start getting some problems with being able to do the job of the kidney. And so you can get kidney damage. Or if it's in your eye, you can get what we call retinopathy, basically meaning that the retina is not working properly. So you can have kidney damage or retinopathy. You can have aneurysms, arteriosclerosis, or arteriolosclerosis. And these are all related to the fact that the blood vessels are breaking or they're becoming more firm. And this is all on the side of receiving pressure.