in this video we're going to start off by looking at what the circulatory system is and see why most mammals like ourselves have a double circulatory system then we'll take a closer look at the heart and cover the names of the different chambers and vessels now the circulatory system which is also sometimes called the the cardiovascular system is an example of an organ system which means that it's made up of a group of organs that work together to perform a common function in this case those organs are the heart the blood vessels and the blood and the role they're performing is to transport substances around the body more specifically the blood is the fluid which carries all of those substances such as oxygen and nutrients cells and waste products then the blood vessels hold the blood and direct it around the body and the heart pumps the blood to ensure that it keeps flowing through the vessels in this video we're going to focus on the heart but we'll cover the blood and blood vessels in other videos so first of all why do we call it a double circulatory system well basically it's it's because it contains two separate circuits there's this top one called the pulmonary circuit where blood flows from the heart around to the lungs and then back to the heart again and then there's the systemic circuit where the blood flows from the heart around to all of our body tissues like our muscles brain liver and so on and then flows back to the heart so to put all of that together blood's pumped from the heart around the lungs and back to the heart and then it's pumped around the body and back to the heart and that process keeps repeating and repeating if we take a closer look at the heart now this is an organ and you can basically think of it as a big muscular pump inside the heart are four chambers these two at the top are called Atria and these two on the bottom are called the ventricles then in between the Atria and ventricles on either side are the atrio ventricular valves which ensure that blood only Flows In One Direction from the Atria into the ventricles now whenever you look at an image of the heart like this one it's as if the heart belongs to another person who's looking at you front on so when we label the left and right side of the heart it's actually their left and their right that's important not ours this means that the left side of the heart is over here on our right and the right side of their heart is over here on our left so just remember that the left and right seem to be the wrong way around but this is why so putting that together the four chambers are the right atrium and the right ventricle with the right Atri ventricular valve between them and then the left atrium and the left ventricle with the left Atri ventricular valve between them also you might notice on some diagrams that the left ventricle has a thicker muscular wall than the right ventricle this is because the left ventricle has to pump blood all the way around the body whereas the right ventricle only has to pump it to the lungs which are much closer the next thing we need to look at is all of the blood vessels that enter and leave the heart in your exam you probably won't get a diagram this complex instead you'll be given a simpler one like this and you'll often see the whole circulatory system represented like this too and you'll need to be able to identify each of the structures and blood vessels so starting here let's label each part as the blood travels around this first blood vessel is the venina Cara which is the body's largest vein and is where deoxygenated blood flows from the body into the heart the deoxygenated blood is now here in the right atrium and as the right atrium fills with blood it contracts and pumps the blood down here into the right ventricle the right ventricle then also contracts and pumps the blood into this blood vessel called the pulmonary artery which carries the blood to the lungs where it can become oxygenated the blood then leaves the lungs VI the pulmonary vein which carries it here to the left atrium once it's full the left atrium contracts pumping the blood down into the left ventricle which after short delay then also contracts and pumps the blood into this blood vessel the aorta which is the largest archery in the body the blood from the aorta then travels around the body to our tissues where it exchanges gases and nutrients and then comes back to the heart VI the reava to restart the cycle All Over Again One Last Thing Before we finish is that the heart muscle itself also needs its own supply of oxygenated blood and it gets this from small arteries that Branch off the aota called coronary arteries these vessels encircle the heart and make sure the muscle tissue gets all the oxygen and nutrients that it needs to keep Contracting if these coronary arteries get blocked though then it could lead to coronary artery disease or a heart attack if you haven't heard yet you can find all of our 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