Online College Courses for Credit

2 Tutorials that teach Blood Pressure
Take your pick:
Blood Pressure

Blood Pressure

Author: Amanda Soderlind

Understand how blood pressure is measured and regulated, as well as common disorders.

See More
Fast, Free College Credit

Developing Effective Teams

Let's Ride
*No strings attached. This college course is 100% free and is worth 1 semester credit.

46 Sophia partners guarantee credit transfer.

299 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 33 of Sophia’s online courses. Many different colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.


Source: Video and Images Created by Amanda Soderlind

Video Transcription

Download PDF

Welcome to this lesson on blood pressure. Today we will be identifying what blood pressure is, as well as factors that can effect blood pressure. So blood pressure is just the pressure that's exerted on the walls of your vessels by your blood. So as blood moves through blood vessels, it's exerting this pressure on the vessels. And that pressure is what we call our blood pressure.

So heart contractions are actually what produce this blood pressure. As blood is pushed out of the heart and into the vessels, it produces this blood pressure. And blood pressure is actually highest in the aorta. So right as it's being pumped out of the heart into it aorta is where it has the highest pressure. And the pressure will decrease as it moves throughout the rest of your vessels.

So there's actually two types of blood pressure we're going to discuss, systolic and diastolic pressure. So if you've been to the doctor's before and they've taken a measurement of your blood pressure, they'll report that measurement with two numbers. It'll be one number over a another number. And those two numbers refer to the systolic and diastolic pressure.

So your systolic pressure is the highest pressure in the aorta while blood is being pushed into it as the left ventricle contracts. So basically, as that left ventricle contracts, it's going to push blood up into the aorta. And that's where the pressure is going to be the highest.

It's coming right from that ventricle as the ventricle has contract. So it's going to have a high pressure at that point in time. And that's what we call our systolic pressure.

Diastolic pressure is the lowest pressure in the aorta, when the heart is relaxed. So when we're measuring our blood pressure at the doctor and they report that number, they're reporting the highest pressure in the aorta over the lowest pressure in the aorta.

So the healthiest blood pressure is under 120 over 80. So that first number there is our systolic pressure, or the highest pressure in the aorta. And the second number is the diastolic pressure, or the lowest pressure in the aorta.

So hypertension is a condition where a person would have chronically high blood pressure. And having this chronically high blood pressure can lead to various types of illnesses, which can lead to atherosclerosis. It can lead to having increased risk of heart attack, et cetera.

So some risk factors that can cause a person to have hypertension include things like smoking, or obesity, an unhealthy diet, a diet high in cholesterol, their lifestyle, how often they exercise, as well as age. So these are all different types of risk factors that can lead a person to have higher than normal blood pressure, which can lead to other serious health effects.

So high blood pressure is called hypertension. There is actually another condition called hypotension, which is chronically low blood pressure. So those are kind of the two ends of the spectrum of blood pressure disorders, chronically high and chronically low.

So our blood vessels can manage our blood pressure by constricting or dilating. So our blood vessels have this smooth muscle that surrounds them. And they're made of kind of an elastic tissue, which allows them to either constrict or dilate. And they do this to help manage our blood pressure. So I'm not talking about a person who has chronically high or chronically low blood pressure. But if there are instances in which for some reason the blood pressure increases or decreases, our blood vessels can constrict or dilate in order to help manage this.

So let's take a look at an example here. So if we have an increase in our blood pressure, our vessel will dilate in order to help maintain homeostasis. So this is called vasodilation. So vasodilation is when a blood vessel will dilate in response to an increase in blood pressure. So if there's an increase in blood pressure in this vessel, the vessel will dilate in order to help maintain homeostasis, to maintain or to regulate a normal blood pressure.

So on the other hand there, we have vasoconstriction. So this is in response to a decrease in blood pressure. So if for some reason our blood pressure were to just drop, our vessels would be able to contract, or to constrict. And then this would allow again homeostasis to be maintained. It would allow those vessels to regulate our pressure. So if our blood pressure were to drop, by constricting, it's providing a smaller area for that blood to move through, and therefore helping to increase the blood pressure back to a normal state.

So that's vasoconstriction and vasodilation.

So this lesson has been an overview on blood pressure, as well as factors that can influence our blood pressure.

Terms to Know
Blood Pressure

The pressure that blood exerts on the wall of a vessel that is measured in units of millimeters of mercury (mmHg). Blood pressure is the driving force that creates blood flow throughout the vessels of the body.

Diastolic Pressure

One of the two measures of blood pressure, diastolic pressure is a lower pressure that occurs when the left ventricle of the heart is in diastole (resting) which causes the pressure in the systemic arteries to drop.


The clinical term for high blood pressure, a person is considered to be hypertensive after three consecutive measurements of 140/90 mmHg or higher.

Systolic Pressure

One of two measures of blood pressure, systolic pressure is a higher pressure that occurs when the left ventricle of the heart is in systole (contracting) and pumping blood into the arteries, causing their pressure to increase.


A term used to describe when the muscular walls of a vessel tense, causing the diameter of the vessel to decrease. Vasoconstriction increases blood pressure and makes it more difficult for blood to flow through a vessel.


The term used to describe when the muscular walls of a vessel relax, causing the diameter of the vessel to enlarge. Vasodilation decreases blood pressure and makes it easier for blood to flow through a vessel.