hello everybody in this video we're going to cover the heart and I'm going to break it up into two pieces this first half we'll cover sort of the basic anatomy of the heart so in this first video that I'm going to make we're going to learn about the components of the cardiovascular system so let's start out with the location of the heart the heart is located in the medius denum and it is in this pericardial cavity in the pericardial cavity in your thoracic cavity uh the pericardium is the Cirrus membrane that encloses the heart and I like this picture it kind of shows like if the Paris if the Cirrus pericardium you see this like kind of continuous membrane with the cavity with fluid in it and if the heart sort of sits in it and kind of folds it around so you end up with two membranes a outer membrane called the parietal layer and an inner membrane called the visceral layer and you have this fluid in between and a lot of times this visceral layer is just called the pericardium and the oh I'm sorry the visceral layer is called sometimes the epicardium and the parietal layer is just called the pericardium right so you'll see that quite a bit and this um has a it's very important for the heart that it has this kind of cushion this fluid filled cavity around it because the heart is constantly beating and you could imagine that if with every heartbeat the heart pushed against other organs that would be a lot of friction the heart would be encountering every day and probably cells would die quite often because of that friction so this little fluid filled cavity this pericardial cavity protects the heart so that it can beat without uh friction um it's sort of a lubrication so let's look at the layers of the heart wall so like I just mentioned you have your pericardium on the outside and then you have um the visceral layer of the pericardium which is often called the epicardium so the epicardium is sort of this most outer layer of the heart it's very very thin under that you have The myocardium which is going to be muscular it has that myo prefix and of course this is cardiac muscle because it's a heart and this is a very muscular organ it's mostly muscle right and internal to that you'll have this endocardium and the endocardium is made of endothelial cells with connective tissue underneath them and this endothelium it's usually very smooth you don't want blood red blood cells to be damaged as they're being pumped through the heart so it's pretty smooth and slippery to facilitate mov movement of the red blood cells and not damage the red blood cells so let's look at some of the anatomy of the heart we're going to start with the four chambers and kind of go chamber by chamber and take a look um the heart is made of four chambers we have two Atrium or Atria which are superior Chambers and these are sort of receiving Chambers for blood and then we have two vent VES the right and left ventricle which are my pumps right these ones are going to pump blood to leave the heart so that's important to remember and also it's important to remember that this heart is in anatomical position right so left is anatomical left right is anatomical right a couple of these structures we have talked about already uh but the blood that's returning to the heart from the body after it's been delivered its nutrients comes from the inferior venne Cava and the superior venne Cava and blood that's leaving the heart mostly goes through the aorta and then we have that descending aorta in our inferior venne Caba right these kind of ran down the center so let's go through this starting with the right side of the heart and we're going to kind of just go chamber by chamber but I'm going to be pointing out lots of structures besides just the chambers so the right side of the heart in general is part of the pulmonary circulation so the right side of the heart is responsible for receiving blood from the body and sending it to the lungs to be oxygenated all right so that's what the right side of the heart is all about receiving blood and sending it to the lungs so it receives blood from three different vessels just mentioned this in inferior and Superior vava um but then also my coronary sinus right my coronary sinus so this is from the coronary circulation the blood coming back from coronary circulation comes in through here um if you look at the inside of this vessel you can or this Atrium you can also see this fosa ovalis and that's the little remnants from um from when the heart has a hole in it during fetal development so we talked about that in the Le in the previous lecture this is kind of what's left over so you can see that little indentation there so blood's going to come in through your Superior and inferior vava through your coronary sinus and this Atria will fill with blood there is a valve the tricuspid valve when the tricuspid valve is closed the Atria can fill with blood blood when it is open the blood will move from this right atrium into the right ventricle right so this is called the tricuspid valve it's also sometimes called the right AV valve or atrio ventricular valve so from here we go into the right ventricle if you look at the surface of the right ventricle you can see that there are these sort of ridges these are the Tuli carnier they're raised fibers of cardiac muscle they have to do with the cardiac conduction system um the the surface is still smooth but there're these sort of raised fibers you can see the blood is going to flow into this right atrium or right ventricle from the right atrium to do that the valve has to open my tricuspid valve and you can see these cordex tendon right here cord tendon um they're being labeled over here actually but you can see there are some in the right ventricle as well and these are um colloquially called heartstrings and they're what holds the um the little cusps of the valve into they they they pull the cusps of the valve sort of into The ventricle so that they never go up into the Atria right so when this valve opens you want it to open into the ventricle but not up into the Atria so they kind of anchor those the parts of the valves in place so that this happens The ventricle is a pump so when this ventricle contracts it is going to shoot blood up through another valve right here called my pulmonary valve it's also called a semi lunar valve through this pulmonary valve into this pulmonary artery so take a look at this left pulmonary artery right here then I have a right pulmonary artery so there's this just pulmonary trunk that branches off into a left pulmonary artery which is going to go left lung and a right pulmonary artery which is going to go to the right lung take a look at them they are colored blue and they're colored blue here to signify that they are still C carrying deoxygenated blood even though they are arteries that are moving blood away from the heart they're carrying deoxygenated blood so these left pulmonary artery and right pulmonary artery are going to carry this blood to the lungs it's going to get oxygenated in the capillaries of the lungs and it's going to come back to the heart through these pulmonary veins through these pulmonary veins in the pulmonary veins you can see our color Ed red so here's an example of oxygenated blood returning to the heart uh through veins so just remember that when it comes to veins and arteries it's um the correct definition of them is arteries are taking blood away from the heart veins are taking them towards the heart here you can see that the idea of them being oxygenated or deoxygenated are flipped right I'm carrying oxygenated blood towards the heart through veins I'm carrying deoxygenated blood away from the heart through arteries okay so that's my right side of the heart blood comes into the right atrium uh from the rest of the body goes into the right ventricle and then is pumped to the pulmonary system to the lungs to be oxygenated when the blood comes back from the lungs it is going to empty into the left Atria Atrium the left atrium over here so you can see I've got my left pulmonary veins my right pulmonary veins bringing oxygenated blood into the heart and I don't have it in the slide but look in your book it's a good idea to look at this part um from the back the the posterior View and you can see a little better those pulmonary veins right but the pulmonary veins are coming back to my left Atria they're going to fill up and then again I have another valve this valve is called um oops WR this called valve is called my bicuspid valve or my mital valve and that's going to prevent blood from flowing down to the left ventricle before we are ready for it to so once it's time the blood will flow from the left atrium through that bicuspid or mitro valve into the left ventricle the left ventricle so the left ventricle is larger than the right ventricle and this picture here does a great job of showing that it also is much much stronger in terms of the cardiac muscle that surrounds it you have much thicker cardiac muscle surrounding your left ventricle then you do your right ventricle and that is because when the left ventricle contracts it is going to push blood up through another valve it's going to push BL uh blood up through this aortic valve here oh and into the Atria I thought my pen wasn't working but it's because it's red and I'm trying to draw on red so just couldn't see it um but yeah the blood's going to be pumped from the left ventricle through this aortic valve into the arch of the aorta and then out to the rest of the body so it makes sense that it has to be stronger because it has to send blood much much further so in reality these two systems are working at the same time so the reason I kind of included this GIF is so that you could see that the left and right Atria are filling up together and the left and right ventricle are Contracting together to expel blood they're just s sending them to different places but they're doing this together at the same time so with each heartbeat you're sending blood to the lungs and to the rest of the body and it's coming back from the lungs and the rest of the body and the yellow fibers here this is part of the cardiac conduction system which will be in the next video but I'm just going to be quiet right now and let you watch it for a couple Cycles all right so you guys can pause here and work on your notes so describe the pericardium and its function what are the three layers of the heart and what are they made of describe the flow of blood through the chambers of the heart including any valves that the blood passes through and any arteries or veins that it passes through you guys can go ahead and pause here and then press play when you're ready to move on another important feature of the heart is its fibrous skeleton uh so this is sort of this connective tissue this fibrous uh core that sort of holds together the valves in the heart so when we look at all four of my valves they have this fibrous ring around them and they're all actually connected to one another so even though there's this is a really interesting cut of the heart I think uh without the Atria and you can see all four valves um but this fibros skeleton it serves as a point of insertion for different types of cardiac muscle bundles it prevents over stretching of these Valves and it acts as an electrical insulator as our um Action potentials are being sent through the cardiac muscle cells right so this is a pretty cool picture you should just I don't know it's just very neat I think you can see your pulmonary valve here you could see your aortic valve here so these two are both the same kind of valves they're semi lunar valves and then you can see your bicuspid valve and your tricuspid valves so let's talk a little bit more about those valves because they're actually extremely important uh they open and close mostly in response to changes in pressure right as the different chambers of the heart contract and relax pressure changes are created and this is mostly what opens and closes these valves so we had two kinds of valves really we had the left and right atrio ventricular valves um this was my trius bit in bpid Valves and then I had my left and right semi lunar valves which was the pulmonary valve and the aortic valve right um so if we take a look at these we can see this is a this is the bicuspid valve but it would be the same for the tricuspid valve they are built a little different um this guy's got little cusps so it's called by cuspid I think you can see the cusps a little better in this image or you can see it maybe in this image but they're called bicuspid or tricuspid because there's like two cusps that's why it's called that right so you can see them I think you can see them best right here right like two little cusps um so when the valve is open the strings are holding the flaps Into The ventricle so that the the cusps don't go back up into the Atria and blood only flows down into the ventricles when they're closed blood won't be able to get through the other two valves the pulmonary valve and the aortic valve are semi lunar Valves and these ones kind of work similarly to the valves that we looked at that in the veins of your legs where they close as BL as um Blood Falls back and fills up these cusps so you can imagine you know blood gets shot through here as soon as the heart relaxes the blood kind of pulls back fills these cusps and it they end up blocking the vessel so that it can't go backwards at all right and the way that this blood moves forward is as the pressure changes from chamber to chamber so for this one this is the aortic valve uh when the pressure is greater in the left ventricle than the aorta then the blood will flow from the left ventricle into the aorta so that's going to happen also as the because of the left ventricle Contracting so this uh picture is very nice kind of looks like that other one but it also shows you the opening and closing of these valves and my little GIF kind of showed how the two ventricles are Contracting almost at the same time in the two Atrium so you can see that they're sort of open as a set the bicuspid valve and tricuspid valves will be open at the same time letting the blood go from The Atrium Atria to the ventricles and then my pulmonary valve and aortic valve the two semi lunar valves would be open at the same time as The ventricle contract and shoot the blood out the right ventricle sending it to the lungs and the left ventricle sending it to the rest of the body so we've talked about this a couple times but I do like this diagram so I just wanted to include it again uh but this is our systemic and pulmonary circulation right so we've got our the blue here is showing all the de the pathway of deoxygenated blood to the heart and through the heart and the red is showing the oxygen rich blood which is part of the systemic circuit it's going to go to the rest of the body right and next week we'll talk about the respiratory system so we'll learn a lot more about what happens to the blood when it goes to the lungs as part of this pulmonary circulation and then the third uh type of circulation we're going to talk about here is coronary circulation because actually the the heart itself is a very energy intense organ it's always beating right and it has been since before you were born so it needs a constant supply of oxygen and food and other nutrients to keep those muscle cells going um so actually you have these coronary arteries this right coronary artery and left coronary artery that Branch off of your aorta almost immediately so as blood goes from left ventricle to aorta some of it is going to go into these right and coronary arteries and left coronary arteries right and then the arteries Branch off to um kind of cover the whole heart so that all the different cells of the heart get the oxygen and the nutrients that they need and then we'll have coronary veins that take away all the waste and the carbon dioxide and carry the deoxygenated blood back and they all converge at that coronary Sinus I showed you where that entered the right atrium and you can kind of see it in this picture so this picture actually you can see a little better the right coronary artery coming off the aorta and the left coronary artery coming off the aorta and then they Branch into smaller and smaller arteries eventually capillaries and then they'll go into veins and go back and you can see this coronary sign it's actually on the posterior part of the heart which is what they're trying to show in this image that's why it's like faded so you can like see on the other side of the heart and that will drain into the right Atria all right so go ahead and pause here and explain how the two types of heart valves open and close and how they keep circulation moving and not backf flowing uh describe the pulmonary and systemic circulation and describe coronary circulation and this actually where I'm going to end the video and I'll make a second one that covers cardiac muscle tissue and uh the conduction system