follow your heart it's advice that makes no sense at all your heart doesn't have thoughts or feelings or anything that's all in your brain your heart is just a pump it's an important pump and it's going to pump blood throughout your body through your arteries but it's not something to follow unless of course your red blood cell in which case you should follow the path that the heart is pumping you through and that's what this video is about we're going to diagram out the path of blood flow through the heart and through the vessels that connect to the heart and finally at the end you have a couple chances to practice this path of blood flow and get really good at it let's jump to the white board and get started so i have left and right marked on our diagram and before anyone accuses me of not knowing my left or my right remember the person is facing us so their left would be on our right and their right would be on our left i've got the basic outline of most of the heart here everything in dark red is going to be muscle heart is mostly muscle because it's an organ that pumps and it's going to do that by contracting cardiac muscle i also have a couple valves right here and right here and this is going to divide the heart up into these four chambers we have the right atrium and we have the right ventricle and then on the other side on the left side we're going to have the left atrium and then the left ventricle and blood is going to flow from the atrium to the ventricles and then outside of the heart we'll get into that in just a second and of course we have a lot of blood vessels that take blood into and out of the heart which i'm drawing on the diagram now okay so our diagram just got kind of complicated but we're going to take it step by step to follow the path of blood flow through the heart and all these blood vessels so as the diagram is being colored in i want to point out something that everything i label in blue is where oxygen poor blood or low oxygen blood is traveling and everything that i label in red is going to be where oxygen rich or high oxygen blood is going to be traveling now the blood vessels aren't blue and they aren't even red the blood vessels are more of kind of a grayish color and our blood itself is only ever red it'll be a slightly darker shade of red when the oxygen levels are low and a slightly brighter shade of red whenever the oxygen levels are high but it's only ever red never blue and we're just using blue and red on the diagram to indicate where the blood is oxygen poor that's going to be blue and where it's oxygen rich which we'll color in red but again that's just to help us follow the diagram a little bit easier and right away you'll notice something that on the right side of the heart everything is in blue meaning it's low oxygen blood and on the left side of the heart everything's in red meaning it's high oxygen or oxygen rich blood so even though our heart is one pumping organ it's really kind of two separate pumps one half is going to pump the low oxygen blood and the other half is going to pump the high oxygen blood i'm going to start with the right atrium just because we got to start somewhere but i could really start anywhere to describe the path of blood flow so starting with the right atrium the blood is going to flow from there down into the right ventricle and it's going to flow through a valve called the tricuspid valve the whole purpose of a valve is to only let blood flow through one direction like my favorite band and therefore preventing blood from flowing back the wrong direction so whenever blood flows from a right atrium down to the right ventricle and then the heart contracts and pumps blood from the right ventricle through this next valve this previous valve the tricuspid valve will shut closed so that no blood can pass back into the right atrium and that's really important if blood is going back the wrong way then not enough blood is going to get out of the heart to get to wherever it needs to go this particular valve the tricuspid valve you can't see it in the diagram but it really has three points of attachment called chordae tendineae and they're going to connect down to the bottom of the right ventricle whenever that right ventricle contracts and pumps blood out through this artery then the tricuspid valve will shut so that no blood can pass backward into the atrium okay so from the right ventricle whenever the heart contracts it's gonna pump blood up through this valve which is called the pulmonary semilunar valve semilunar is just describing the shape and pulmonary means the lungs so we're gonna see the name pulmonary and a lot of structures right now just remember whenever you see pulmonary it's either going to or from the lungs so right ventricle through the pulmonary semilunar valve into the pulmonary artery again pulmonary means lungs artery means it's moving blood away from the heart just remember artery away the pulmonary artery just means away from the heart and toward the lungs you'll notice the pulmonary artery is going to branch to two sides that's because it needs to go to the left lung it also is going to pass back here to connect to the right lung so blood will flow from that pulmonary artery into the left lung and there the blood is going to receive oxygen from the alveoli in our lungs and it's going to give away the waste products co2 to the alveoli in our lungs so that we can then breathe that out our diagram is about to go from everything being colored blue to everything being colored red because our blood has gained that oxygen meaning that it's gone from kind of the darker red to the brighter red but again our blood vessels aren't blue or red they're really just sort of a gray and we're using that color change to show where the blood has oxygen and where it doesn't from the left lung it's going to travel through the pulmonary veins back into the heart and that'll happen both on the left side and of course on the right side because we have two lungs so all of these pulmonary veins these two right here as well as these two over here which are gonna pass behind the heart those all connect to the left atrium right there from the left atrium the blood is gonna pass through a valve called the mitral valve or it's also called the bicuspid valve because it's got two points of attachment of the coordinate tendineae or the heart strings so left atrium through the mitral or bicuspid valve into the left ventricle now notice something the left ventricle has a lot thicker heart muscle around it take a look at the thickness of that muscle compared to the thickness of this muscle that's because the left ventricle has to pump blood throughout the whole body all the way up to your brain to your fingers and your arms all the way down to your toes it's got to pump blood pretty much everywhere so it'll have to have thicker stronger muscle in order to get it throughout the whole body whereas the right ventricle if you remember that just pumped the blood to the lungs and the lungs aren't that far away so it doesn't need to contract as strongly and so it's got thinner muscle around the right ventricle so the left ventricle is going to pump its blood through a valve we can't see right there but it's behind that blood vessel called the aortic semilunar valve again semilunar is just describing its shape and aortic because it's going to pass through our biggest artery called the aorta the aorta is going to go up and over in what we call the aortic arch and then it's going to go down behind the heart through what we call the descending aorta the aorta like i said is the biggest blood vessel in our body and all of the blood that comes out of the heart is going to pass through that except for the blood going through the coronary arteries now i don't have the coronary arteries labeled on our diagram but here's another image of the coronary arteries they're tiny arteries they actually branch off from the aorta there and there and they're going to take blood to the muscle in the heart basically they'll give blood to this muscle right in there and there all around the heart and that's really important if one of those coronary arteries gets blocked then we have a heart attack because the muscle in the heart isn't getting the oxygen that it needs and that tissue is going to start to die off so just remember the coronary arteries branch off from the aorta they wrap around the heart like a crown which is what coronary means and they provide the heart muscle with blood if they get blocked that's a heart attack but most of the blood is going to travel through the aorta some of it's going to travel through these three branches that branch off the aortic arch and that's going to connect to the upper body's tissue capillaries that would be capillaries in your brain in your shoulders and your arms and your hands everything basically above the heart those three branches are going to take blood to all those different parts so in those tissue capillaries the blood is going to give its oxygen to all of the cells there they all need to undergo cellular respiration to produce usable energy in the form of atp and they need oxygen to do that but they've also produced co2 as waste so the red blood cells are going to grab that co2 so that they can bring the co2 back to the lungs so that we can breathe it out now from those tissue capillaries all the blood is going to return to the heart through this large vein called the superior vena cava now while that's happening blood is also flowing through the descending aorta to all of our lower body that's going to include like our legs and our torso and everything again the red blood cells are going to be delivering their oxygen and gathering co2 and that blood is going to return to the heart through the inferior vena cava now a quick note about the heart here it's really only the arteries that the heart pumps the blood through blood gets returned to the heart through these veins but the veins are just going to use smooth muscle that's on the outside of the veins as well as gravity for the superior veins to bring blood back to the heart so the heart pumps blood away from itself but it doesn't pump blood back to itself we use smooth muscle and the movements of the body in order to get that blood back to the heart and so at this point all the blood has returned back to the right atrium which is where we started from okay that was a lot the only way to learn all of this is to practice going through the stages of it on your own over and over again i'm gonna recap everything a little bit quicker now and then you'll have a couple chances to practice after this we started just because i chose to in the right atrium from the right atrium blood is gonna pass through the tricuspid valve into the right ventricle when the heart contracts blood is going to pass from the right ventricle through the pulmonary semilunar valve through the pulmonary artery which is going to branch to the left and right lungs the blood is going to receive oxygen and give off its co2 and then the blood will return to the heart newly oxygenated through the pulmonary veins pulmonary veins from both sides connect to the left atrium from the left atrium the blood's going to travel through the mitral or bicuspid valve into the left ventricle the left ventricle is going to pump the blood through the aortic semilunar valve that blood's going to travel up through the aorta it's going to connect to the coronary arteries to supply the heart muscle with blood but most of the blood's going to travel up through the aortic arch either through these three branches which connect to the upper body capillaries or down through the descending aorta which is going to connect to the lower body tissue capillaries in those tissue capillaries the blood is going to give off its oxygen and take carbon dioxide and travel back to the right atrium either through the superior vena cava or through the inferior vena cava that brings us back to the right atrium which is where we started one more time even quicker right atrium tricuspid valve right ventricle pulmonary semilunar valve pulmonary artery the lungs pulmonary veins left atrium mitral or bicuspid valve left ventricle aortic semilunar valve aorta aortic arch upper body the descending aorta to the lower body and then back through the inferior and superior vena cavas to the right atrium all right before we go i want to give you a couple more chances to practice take a moment pause the video starting with the right atrium see if you can name all of the chambers valves and blood vessels that the blood passes through in the correct order all right finally for an added challenge see if you can do the same thing now with the diagram not labeled and if you get to the point where you can do that on your own then you know this stuff pretty darn well hopefully this video helped you learn the path of blood flow through the heart one quick fun fact before we go a lot of people think that the heart sounds that your heart makes a lot of people think that's your heart pumping but technically it's not it's actually the sounds of your valves snapping shut