November 12, 2019


In this video we are going to dive into hypertension
pathophysiology. But before we get started, don’t forget to
download the free med-surg checklist I have for you, that walks you through, step-by-step,
how to study med-surg in nursing school. That link is down below for you to download
it. And while you’re at it, make sure you SUBSCRIBE
to this channel and click the little bell icon to get notified when we post a new video. Now, let’s talk about the pathophysiology
of hypertension. Alrighty, so hypertension just means high
blood pressure. And blood pressure means exactly what it says
it does: it’s the pressure of blood in the blood vessels. And there are 2 numbers that you need to look
at: the systolic blood pressure and the diastolic blood pressure. I know these numbers can be a bit confusing,
so let’s break it down. The systolic blood pressure is the top number,
and that indicates the pressure of blood in the vessels when the heart contracts. So each time your heart beats, it’s contracting
and pushing blood to the lungs and to the body. So the systolic blood pressure is the measurement
of the amount of pressure the blood is exerting on the blood vessels during that heart contraction. Now on the flip side, diastolic blood pressure
is the bottom number, and that is the pressure the blood puts on the vessels when the heart
is relaxed and in between contractions. So when the heart is at rest and relaxed,
how much pressure is the blood putting on the blood vessels? And that is the diastolic blood pressure number. So I’m not going to dive into the blood pressure
criteria here or give you actual numbers. They have actually changed recently, so you’ll
want to check with your nursing school and clinical facility to see what exact numbers
they use to define high blood pressure. I don’t want to steer you the wrong way if
the numbers I use are different from the one’s your school uses. So check with them. So that systolic blood pressure number is
the top number, and we would expect that to be greater than the diastolic number, or the
bottom number because that systolic number indicates the amount of pressure the blood
is putting on the blood vessels during heart contractions, when the heart is actually pumping,
right?. Whereas, the diastolic blood pressure number
indicates the pressure in between heart contractions, when the heart is more relaxes. so that higher number should be greater because
there is a higher pressure. Okydoky, so let’s really get down into the
pathophysiology here. Because we know that blood pressure is the
pressure the blood exerts on the vessels, blood pressure changes when the PRESSURE changes. And some things that can impact the pressure
are: the amount of blood that the left ventricle pumps out (this is called the stroke volume),
the size of the blood vessels (which changes the peripheral vascular resistance), and the
heart rate. So any changes to these 3 things can cause
changes in the blood pressure. So let’s talk about each one of these a little
bit more. So in the case of stroke volume, this means
the amount of blood that the left ventricle pumps out to the body, so if stroke volume
increases, meaning the amount of blood the heart is pumping out increases, what’s going
to happen to the blood pressure? It’s going to go up, because the amount of
blood increased. Now let’s put a visual to this. I like to think of blood pressure as a hose. So, when you turn the hose on just slightly,
it just trickles out right? That represents a low stroke volume because
there’s LESS water coming out. Now, if you try to have a water fight with
just a small trickle of water, it’s not super effective right? Because there’s just not enough pressure. You can’t spray someone enough with just a
trickle of water. So if the stroke volume is lower, we would
expect the blood pressure to be lower. Now, on the other hand, if you crank the water
hose way way up, it spews out everywhere and there’s a ton of pressure right? You’ve changed the VOLUME or the AMOUNT of
water coming out. So with a higher stroke volume, we would expect
a higher blood pressure. If you’ve had a water fight before and this
example is making sense to you, write LOVE in the comments below. I want to hear from you! Now, let’s talk about the size of the blood
vessels. The size of the blood vessels impacts something
called peripheral vascular resistance. When you hear this phrase, “peripheral vascular
resistance,” all I want you to think is to how much is the heart going to need to work
to push the blood out. That all. So, back to our hose example, if the water
hose itself is smaller, or more narrow, what will happen to the pressure? (thumb up) It will increase right? I know you’ve had a water fight at some point
in your life, so what do you do if the water hose can’t reach the person you’re trying
to spray? You put your thumb on it, right? And that makes it spray farther because the
PRESSURE is greater. So you made the hole in the hose smaller,
you increased the resistance, and that increased the pressure. The heart is the same way. If the blood vessels are more narrow, there
is more peripheral vascular resistance, and the blood pressure will be greater. On the flip side, if the blood vessels are
dilated or larger, there is less peripheral vascular resistance, and therefore, the blood
pressure will be lower. And finally, heart rate is the last factor
here. The faster the heart pumps, the greater the
stroke volume, and therefore, the greater the blood pressure. And the slower the heart pumps, the stroke
volume will be less and less, and therefore, the blood pressure will decrease. To remember this, I just like to think about
that water hose having 3 water spikets all going into one hose. So just imaging you’ve got 3 water faucets
or water spikets, and they all lead to the same place. So the more faucets you have, the greater
the pressure, the less faucets you have, the lower the pressure. Heart rate is the same way, the faster the
heart beats, the greater the blood pressure. The slower the heart beats, the lower the
blood pressure. I hope all of that makes sense. Now if this is all clicking for you, write
LOVE in the comments below to let me know. And that is the pathophysiology of hypertension. Now if you want to go even further with this,
and dive into the physiological processes that balance blood pressure, things like the
RAA pathway, baroreceptors, and fluid changes, then you’ll definitely want to join the NursingSOS
Membership Community, where we talk about those processes in depth and how they relate
to blood pressure. So if you need to know how the kidneys and
baroreceptors impact fluid volume and blood pressure, you’ll definitely want to jump into
the NursingSOS Membership Community.

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