How Blood Pressure Works

High blood pressure -- or hypertension -- is elevated pressure of the blood in the arteries. Hypertension results from two major factors. Check out our HowStuffWorks article to learn more about the causes of and treatment for hypertension.

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Episode Transcript

Speaker 1 (00:00):
Brought to you by the reinvented two thousand twelve Camray.
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(00:20):
resolves online fraud safe Secure Visa. Hey, and welcome to
the podcast. I'm Josh Clark Stafford or here at How
Stuff Works dot Com with me, as always is Charles W. Bryant. Chuck.
What's going on? It's good to be here, Josh as always. Yeah, Yeah,
I'm feeling the same way, Chuck. I'm feeling that pretty good.
So you guys might not know this, but Chuck always

(00:42):
kind of keeps me abreast of current events, situations going
on in the world. Would you have for me today, Chuck? Today, Josh,
I have the cause of death results for legendary soulsinger
Isaac Hayes. Yes, the man who scored Shaft died recently.
I'm Jim. Yes he did. He died apparently while jogging
on his treadmill, which is um very sad. Yes, and

(01:04):
it looks like the cause of death is uh stroke
because of high blood pressure. You know, that's funny that
you bring that up, because I've been wanting to talk
about high blood pressure also known as hypertension for a while. Lately.
I'm feeling like this's a good opportunity to do it. Right, Yeah,
let's do it. You know how stuff works. Stuff You
should know. It's not always just fun and games. Sometimes
we want to help people out with a little health advice. Agreed,

(01:25):
So so let's do that, right, let's do it. Well, Chuck,
this doesn't in any way, shape or form qualify me
as any kind of medical professional. But I spent a
trimester in E m T School. Do you know that
about it? Yeah? Yeah, seriously, I had no idea I did, uh,
and I was terrible at it um. For the final
exam for the trimester, uh, the instructor brought in some
of his former students who are now E m T

(01:47):
s and they acted like they were suffering from some
sort of uh terrible medical condition and we had to
figure it out based on the symptoms. Right. Well, I
am a terrible diagnostician. Um, I I landed a victim.
I just made air quotes who was choking? And I
treated her like a burn victim, um, and laid her down,
and I think I started doing CPR or something on her.

(02:09):
And I knew that I had completely missed the mark
when she looked over at the instructor with this what
the heck should I do now? Expression? And He's just like,
keep going, keep going. She grabbed her throat and you
thought that she had burned her neck pretty pretty much. Yeah, yeah,
I failed miserably. Um, But there were a couple of
things I learned. One of them was how important it
is to take care of the old ticker. I mean,

(02:31):
we're we're getting to be about that age, chuck. I
hate to break it to you. I just reached thirty two.
I'm very depressed about that. But five onto that, my friend. Yeah,
so you're pushing forty now pushing, Yeah, and and neither
one of us are in prime physical condition, right, I
think that's a fair assessment. Yeah. Yeah, So I'm no triathlete, no,

(02:51):
And I love bacon. I love it. I love it
so much I can't even begin to tell you. But
one of the problems with bacon is that fat that
we eat and digest gets carried through the blood stream,
and uh, it doesn't always break down like it should know.
It starts to form plaque within blood vessels, which actually
can lead to hypertension. And you want to know how well,

(03:15):
first of all, I think we should just tell people
what blood pressure is, period because people hear the blood
pressure and they don't understand what it is. It's really simple.
Blood pressure actually is all it is is the measurement
of the force of the blood going through your arteries
against the artery walls. Yeah, your your heart actually UM
creates it generates an electrical impulse. The the electrical impulse

(03:37):
travels across the heart and it's picked up by the atria,
which is which contracts. Right, the blood is forced out
of the heart and into the blood vessels. So there
you've got. You've got your systolic pressure, which is the
first number on a blood pressure reading, right, it's something
over something and that's that's the first one, the one
on top. And the optimal for systolic pressure I think

(03:57):
is like one twenty for the average healthy adults once
twenty year or under is what you're looking for right now.
UM to measure this kind of thing, it's it's luckily right.
We don't need trepid nation or any kind of rectal exam.
You can just slap a blood pressure cuff on your arm,
and thanks to our good friend Mercury, we can measure
the pressure exerted on any given blood vessel. Is the

(04:18):
blood car pumps through it? Right? And I I personally
love those things when you get your blood pressure checked.
Ever since I was a kid, I just thought when
the when it constricts around your arm and tightens up
and you can feel your heart beating in your arm,
I just thought it was really neat. And chances are
if you go to a grocery store a drug store,
you might find me sitting at one of their little machines.
It's a it's a great thing. It's a great way

(04:39):
to pass the time. Yeah, but it's not. Actually, I
did some research. It's not always the most accurate read.
So people need to know this when they get their
blood pressure checked by machine at your local Kroger. Uh.
It may have been accurate when they first installed it,
but it needs to be maintained and recalibrated over the years,
so if it's not, it may be off you. You
might can get a good idea that you should look

(05:00):
into it further, but you shouldn't, you know, make any
medical decisions based on what you uh, what you get
when you're picking out your hot dog buttons and you're
we we hear how stuff works. Strongly advise you to
console the physician for just about anything, including blood pressure readings.
But yeah, at the very least, it's it's kind of
a joy to have your arms squeezed by a robot.

(05:22):
You never know if if the thing's gonna go berserk
and just snap your arm right off. I think, yeah,
that's part of the fear, is that it will take
on a mind of its own and sever my arm off. Yeah. Yeah,
I think that's everybody's fear. So what about diastolic? That's
the bottom number, right uh, And I think for a
healthy adult eighties a good reading. Um so, the the

(05:42):
the good blood pressure reading, a very healthy blood pressure
reading is one eight. That bottom number represents what the
normal relaxing or relaxed pressure on a vessel, uh is
when the heart is at rest, when when the blood's
not being four wors through. It's just you know, the
hearts at rest blood vessels just sitting there like oh,

(06:03):
I'm waiting for the next pump, you know. Uh, so
eighties good? Um. And the thing is is those numbers
can change just a little bit and make some really
you know that it can be it can be really
bad with just a couple of numbers being off. Right. Well,
tell me more, Well, I will tell you more, Chuck.
Let me tell you about the third kind of pressure reading.
It's called pulse pressure. Uh. It's not uh necessarily widely

(06:27):
accepted yet, although it's really gaining traction. So pulse pressure
is just the difference between the systolic and diastolic pre
pressure readings. Right, So if one twenty over eighty is
optimal health for blood pressure reading, then forty would be
the optimal pulse pressure. It's the difference when eighty got you.

(06:47):
If it's uh, if it's a high, or if the
difference is high, uh, you've got problems. It can mean
that your your blood vessels are hardened, that they have
lost elasticity. There's there's all sorts of problems with it.
It can also mean that your heart is getting a
little too buff. Hypertrophy, all right, buff in this case
is not good. No, it's good for the bicep not

(07:09):
good for the heart because an overly buff heart can
can fail a lot more easily. Yeah, so we've got
the pulse pressure difference, and and I read that every
ten um millibars of mercury, which is the pressure reading difference,
actually increases your chance of stroke by like eleven percent.

(07:29):
So so it's important to keep an eye on your
blood pressure and and to keep an eye on whether
or not you're you're hypertensive or pre hypertensive. Um. And Uh, again,
the best way to find that out is to just
go visit your doctor regularly and get some blood pressure reading, right,
because hypertension a k A. High blood pressure. There's pre
high pertension, which you mentioned, which is before it's a

(07:50):
real problem, but it's when you can really correct it
with your diet and things like that. And then um,
secondary hypertension and hypertension or when things get out of hand,
when you're in danger of maybe a cardiac arrest or stroke. Uh.
And then the other thing I want to talk about,
which I thought was kind of interesting, was white coat hypertension.
Give it to me, this sounds interesting. Yeah, this is when, uh,

(08:12):
your your blood pressure actually elevates when you go to
the doctor. Oh, from from being nervous. I'm not sure
if it's from being nervous or not, but it's you
have a different blood pressure. White coat obviously it's what
the doctor wears and the doctor's office and you at home.
And I guess you know, my easy answer would be
don't come into doctor and you won't get high blood pressure.
But that's that's no good advice. And you should also

(08:35):
be wary of any doctor that doesn't wear a white coat, right, Yeah, yeah,
that's that's good advice too. That is interesting. They've also
found that um pregnant women can often demonstrate higher blood
pressure just because of their pregnancy as well. It can
be normal before the pregnancy, it can be high during
the pregnancy, and then go back to normal afterwards. To
the impression I got was that we didn't have a

(08:57):
really good read on exactly why that happens. We just
know it does happen, much like the white coat blood
pressure exactly. And uh, I've got some other stats for
you if you just want me to do. You know
how I feel about stats, Chuck, don't tease me, give
me to me. Well, uh, they did some studies on
percentage of adults twenty years over that have high pertension

(09:18):
or that are taking medication for hypertension. And overall thirty
percent of men and women are following into that category,
which really, yeah, which is more than I thought. Over
twenty I would think that the maybe a stat over
forty or fifth women come in and right at the
thirty percent mark. Men a little bit less believed or
not at pent and uh, the stat I thought was

(09:38):
interesting is that poor people are thirty at thirty four percent,
whereas non poor or twenty eight percent. Well, it makes
a lot of sense, you know. Um the uh, the
poor usually have less access to a healthy diet, right, Uh,
usually less time to eat well or take care of
themselves since they're working. Cheaper packaged foods and I are

(09:58):
loaded with sodium and podium and salt. It's a big
contributor to high blood pressure. So that kind of does
make sense. Well, Chuck, why don't you tell us some
ways that we can avoid hypertension? And if you have hypertension,
I mean, what can you do? Well? Uh? Kind of
like with everything else, the doctor tells you eat healthy,
lose weight, lay off the salt, limit alcohol, and quit smoking. Yeah,

(10:19):
and I looked into smoking. Uh, you know, it turns
out that smoking I thought it would stimulate the heart
and would wear it out faster. It turns out that
doesn't happen. Smoking actually goes in and injures your blood vessels.
That's how smoking can cause heart disease and hypertension, which
I found interesting. But yeah, you want to stay away
from the cigarettes, the cigars, any kind of smoking is

(10:41):
going to be bad for your heart, right, And as
far as your diet goes, they have something they recommend
called the DASH diet d A s H stands for
Dietary Approaches to Stopping Hypertension. And uh, what you want
to eat is whole grains, poultry, fish, nuts. You want
to limit fats and red meat. So not some much bacon, huh,
not as much bacon, steak, stuff like that. Yeah, it's

(11:04):
a nice it's a nice treat, but that shouldn't be
your regular, agreed, chuck. So what happens if you do
have hypertension? I mean obviously that there's a there's a
lot of medications out there in the market for people
who are hypertensive, right, Yeah, there's a lot of medications,
but a lot of these have side effects too, so
it depends on how higher blood pressure is as to
whether or not a doctor thinks it's worth it to
get on these meds um and potentially suffer some side effects.

(11:27):
So it's a few points here and there. They'll probably
recommend that you take care of it through diet and
exercise if you have a real problem. Um, there's all
kinds of anti hypertensive drugs, diuretics, uh, sympathetic inhibitors UH,
calcium channel inhibitors, a C inhibitors, and you know they'll
do a good job. But you know side effects like sedation, nightmares, depression, vertigo, uh,

(11:52):
stuff like that. The effects. Yeah, my favorite side effect death. Yeah.
I love it when they say that as pharmaceuticals. Well,
you mentioned sympathetic inhibitors. Is that that would have to
do with the sympathetic nervous system, right, Yeah, that would
control your fight or flight response correct, right, which is
something that we like to talk about under fight or

(12:13):
flight response. Well, if you do have hypertension and you
are being treated for it, take hope. I read somewhere
that six of people who suffer from hypertension recover from it.
They gain control of their blood pressure. It's goods. Go
see your doctor, eat well, quit smoking, watch the booze
all that, and Uh, if you want to learn a

(12:33):
lot more about hypertension, read hypertension in depth on how
stuff works dot com and stick around to find out
how Chuck and I know that the world about in
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(13:15):
You want to tell everybody how we're privy to the
information that the world's about to end, well, Josh, is
not because we're smarter than everyone else, because that's not true. Uh,
it's because we read the article. Are frogs on the
brink of extinction? That's true. Frogs are an indicator species,
and when they start disappearing, everybody else at the top
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(13:36):
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