Hypertension effects on the blood vessels | Health & Medicine | Khan Academy

Hypertension effects on the blood vessels | Health & Medicine | Khan Academy


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.