All right, you guys, welcome back to another video lesson. My name is Eddie Watson, and this is ICU Advantage, where the confidence to succeed begins here, making critical care topics easy to understand. Now, if you don't want to miss out on any future critical care lessons that I do, make sure and subscribe to the channel down below. Make sure you hit that bell icon, though, and select all notifications so you never miss out on a new lesson.
All right, let's begin. In this lesson, let's take a quick look at the flow of blood through the heart. And the heart is really the powerhouse of the circulatory system.
It's continuously moving blood throughout the entire body, providing oxygenated blood and nutrients, while also carrying away waste and returning that deoxygenated blood back to the lungs. Understanding the flow of blood through the cardiac system is vital to being able to understand the problems and conditions that can come up along the way at various points. We do though need to start off with some basic foundations before we begin. So when I'm talking about veins, I'm talking about blood vessels that are carrying blood towards the heart, and then arteries are then blood vessels carrying blood away from the heart.
And then for the sake of our drawing, blue is going to be used to signify deoxygenated blood, and red is going to be our oxygenated blood. So with that out of the way, let's go ahead and take a look inside the heart so we can see some of the structures here. There are four main chambers, two upper chambers called atria.
and two lower chambers called ventricles. And we have one of each on each side of the heart. We have the right atrium, the right ventricle, the left atrium, and the left ventricle. And the atria help to fully load the ventricle before it then ejects blood away from the heart.
The heart can also be divided up into the right and left sides. The right side is going to be responsible for deoxygenated blood going right to the lungs. and then the left side is responsible for oxygenated blood that has just left the lungs. There's also four heart valves that you need to know, one at the exit of each of the four chambers. Exiting from the right atrium, we have the tricuspid valve.
Then exiting from the right ventricle, we have the pulmonic valve. And then exiting the left atrium, we have the mitral valve. This is something that also is known as the bicuspid valve.
And then finally exiting the left ventricle, we have the aortic valve. Each of these valves act as a one-way valve to prevent backflow of blood in the system. And normal valves have three leaflets with the exception of the mitral valve which only has two, hence the name bicuspid.
And then finally there are the blood vessels which bring blood to as well as carry blood away from the heart. The inferior vena cava which has blood originating from the trunk, visceral organs in the lower body, and the superior vena cava which has blood originating from the head and upper body. which these two together bring most of the deoxygenated blood from the body back to the heart and empty into the right atrium. Next, we have the pulmonary artery, which is going to carry the deoxygenated blood away from the heart and then to the lungs to be oxygenated.
From here, we have both the right and left pulmonary veins, which are bringing the oxygenated blood back to the heart and emptying into the left atrium. And then finally, the aorta carries the oxygenated blood away from the heart to the rest of the body. Alright, now that we've covered the structures, let's actually see how the blood flows through the system.
We start with the deoxygenated blood returning to the heart via the inferior vena cava and the superior vena cava. This blood empties into the right atrium. The right atrium then contracts the blood through the tricuspid valve into the right ventricle. The right ventricle then contracts, ejecting the blood through the pulmonic valve into the pulmonary artery.
Now remember, this is an artery because the blood is going away from the heart. but it's also blue here because this is still deoxygenated blood. The pulmonary artery branches and carries blood to the left and the right lungs to receive oxygen and release carbon dioxide.
After the blood leaves the lungs, the oxygenated blood is going to return to the heart via the pulmonary veins. Again, remember that these are veins because they're carrying blood towards the heart, but they're red here because this is now oxygenated blood. The pulmonary veins empty the blood into the left atrium. The left atrium contracts the blood through the mitral valve into the left ventricle.
The left ventricle then contracts, ejecting that blood through the aortic valve, into the aorta, and onto the rest of the body. So one more time, let's just talk through that again. We start with the deoxygenated blood returning to the heart via the inferior vena cava and the superior vena cava. This blood empties into the right atrium.
The right atrium then contracts the blood through the tricuspid valve into the right ventricle. The right ventricle then contracts, ejecting that blood through the pulmonic valve into the pulmonary artery. The blood then travels to the lungs and then returns back from the lungs via the pulmonary veins, which then empty into the left atrium.
The left atrium contracts that blood through the mitral valve into the left ventricle. The left ventricle then contracts, ejecting that blood through the aortic valve to the aorta and onto the rest of the body. And remembering the order of the heart valves can be difficult.
The mnemonic TPMA can help. Toilet, paper, my asset. Tricuspid, pulmonic, mitral, aortic. Alright, that's all I got.
That's the blood flow through the heart. If you guys liked this lesson, please leave a comment or a like down below. It really goes a long way to help support this channel.
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