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
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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.