- All right, today we're going to be talking about the heart and I'm really excited 'cause the heart is one of my favorite things to talk about. So I'm going to start off by giving you a little bit of basic structure of the heart. All right, so to start off I'm going to talk about the basic structure of the heart. Now, please take note that when your heart is sitting in your chest it's a little bit tilted to the right hand side. So it's a little bit at an angle, but whenever I draw it I'm gonna draw straight up just to simplify it for us but take note that it is a little bit tilted at how it actually sits in the body. So we'll start with a little bit of the basics. Now, whenever I draw the heart I'm going to be using two main colors and I will explain why in a moment. One side is going to be blue and the other side is going to be red. The reason for that is blue will be deoxygenated blood. So in this anterior view, I'll label it for us. So here is our right and here is our left. Now take note that the right side of the heart is going to hold our deoxygenated blood. Okay, now the left side of the heart is red because it will hold oxygenated blood. Now from this point on I'll always draw the heart like this just to remind us that the right side of the heart is blue and the left side of the heart is red for deoxygenated and oxygenated blood. All right, so a few other things I'm going to break this heart down. I remember it looks kind of like this heart shape but it's a little less precise in its shape and it's tilted to the right a little bit, but for our reference I'm going to break it into quarters and we're going to label them. Right here is your right atrium. And the abbreviation for that is RA. Now if we have a right atrium what do you think we're gonna have on the other side. That's right, it's gonna be our left atrium. Now, each one of these quarters is basically a chamber within the heart. So it's completely separated. So this black line breaking into fours isn't just for fun. It's actually breaking things into four different chambers and that's why we're naming them all right now. Okay, and the reason why those are broken up in a chain will make more sense later as we explain blood flow going through the heart but just stick with me for now. So on this right side in this bottom area, we're gonna have a different chamber called a right ventricle or RV for short, and then you guessed it, this is going to be our left ventricle or LV so going forward it just takes a long time to write out right atrium, et cetera. So I'll be using the abbreviations going forward but as I describe it, I'll describe it in the true name of those things. Now, I want to draw your attention to another area here. Right here, the bottom, which remember our heart is gonna be tilted to that right side. This bottom area is going to be called the apex of the heart. And it might seem weird for that to be the apex 'cause sometimes when you think about the apex as being the top but apex really just means like peak or point. So that's why it's called the apex of the heart. And then with this tilted a little bit, I'm gonna draw your attention to a different area which is right here. That's going to be the base of our heart, which again seems a little counterintuitive usually I tend to think about the base as being the bottom but in this case it's the right side and a little bit of the left in the superior region of the heart and that's referred to as our base. All right, so now that we have some basic understanding of this, I'm gonna talk a little bit about blood flow and give you one more piece of information of the heart. Now, the heart is sitting in a specific place in the thoracic cavity and there's a name for that. So the name is the mediastinum, which is where the heart sits in the thoracic cavity. Now a few other things that I wanna draw your attention to for in regards to blood flow is we refer to both artery and veins when we're discussing blood flow with the heart. Now I'm gonna give you a little trick. So arteries bring blood away from the heart. So you can remember that because artery starts with an a, and so does away. So a away, artery away from the heart. All right, now the other one that we discussed veins, what do you think those are gonna do? Yep, those are gonna bring blood back to the heart. All right, so here are some basics about the structure of the heart and what we're gonna talk about in terms of this. We're gonna be referring to different arteries and veins that are connected to the heart as we move forward with this. So stay tuned for that, just to remember a away, artery away and keep all of this in mind with the blue deoxygenated blood on the right side and the red oxygenated blood on the left side. Now, before we go through blood flow and how blood moves through the heart in relation to structures of the heart, I wanna talk about lining of the heart and kind of this casing type situation we have so that's what we're gonna talk about next. All right, so we're still in the heart. Now I'm going to draw us a heart just like I talked about where we're instead of drawing it tilt into the right we're just gonna draw it straight up and the right side. This is again an anterior view. The right side is going to be blue and the left side is going to be red. Now this just represent our heart in general. And it gives us a little baseline for some other things we're going to add. All right, so the first thing I want to draw for you is what's really the muscle of the heart. So like the meaty part of the heart I'm going to draw that in this light blue color. And I'm gonna make it a little bit thicker because this is a thicker part of the heart. So this is actually called myocardium. Myo means muscle. Like if you've ever heard of like myofascial releases those are muscles and fascial releases. And then cardium of course refers to the heart just like cardiac, cardiac disease if you've ever heard of that. So I'm just finishing drawing up this nice, thick area and we're gonna label that as myocardium. And remember that myo means muscle. And remember mm is our abbreviation for muscle. All right, so the layer that is deep to the myocardium or most internal of the heart, is something I'm going to draw in green here, which we are going to call endocardium. Now, cardium remember means heart and endo means inner. So that's kind of how you can break down all these words. They really do make sense. Now the next one I'm going to draw is on the out, it's like an outer covering or like sitting on top of the heart tissue. That was going to be this dark pink color. And this is going to be this outer covering sitting on top of the heart. And we're going to call that visceral pericardium. Visceral remember means organ and peri means around. And you don't really need to know what these technically mean, but I'm just writing out for you because I think it's helpful to know. Now the other name for this visceral pericardium is epicardium. Now epi means on top of, so that makes sense too 'cause it's kind of sitting on top of the heart tissue. Now we're going to have actually a little bit of space in between this epicardium in our next layer. So that's why I'm going to draw space in there for us. Our next layer or actually, we'll talk about that space in a moment but our next layer outside of that space, I'm going to draw on purple and that is going to be our parietal pericardium. Another name for this is serous pericardium. All right, so that's the essentially the middle or the most inner layer in right a superficial to that is what we call our pericardial sac. And this sack just kind of hold the heart. It can help kind of like protect it and keep it in place. Pericardial sac. Now the outer most layer on the very outside is again, a little bit of a protective mechanism. I'm gonna draw this in blue and that is our fibrous pericardium. Now drawing your attention to their names again, visceral remember means organ. So this is around the heart on the organ itself. All of these three words for this outer layer they all have pericardium or pericardial in them which means they're surrounding the heart. And this one, fibrous pericardium is fiber. It's just like the name says so it helps protect the heart because it's a little bit tougher and stronger. Now, remember we drew that space in there, that white space and I'm going to label that for us. That is our pericardial space. And that's important because it actually is a space. It's not quite this thick but there is a space in what's filled up and that space is called pericardial fluid. Now, it's not a huge bucket of fluid in there, right? It's just a little bit of fluid actually about two to three tablespoons of fluid is the amount of normal pericardial fluid to have in that space. And essentially the purpose of that fluid is really to protect and decrease friction when things are inevitably rubbing around as the heart pumps and kind of moves in the thoracic cavity. Now, it's really important that we are aware of this because there are certain disorders where you can have too much pericardial fluid. Like there, you can be as a result of infection. You can also have it with something called congestive heart failure and that congestive heart failure leads to essentially just a lot of fluid backup in other areas as well. And a symptom for that is significant weight gain. Because if you're gaining all this weight you're kind of building up all of this fluid, it's a bad sign. So anyway, we can get more into that at another time but here is all of these coverings of the heart. All right, so now that we have all of those coverings done, now we're gonna get to the fun part which is how blood flows through the heart, okay. All right, this is the best part right here. Okay, so blood flow through the heart. Alrighty, let's get rolling. Okay, so just like always, I'm going to draw the heart here. The right side is going to be blue. The left side is going to be red. I'm going to split it up into our four chambers and I'm just going to actually label them for us as well. So right atrium, right ventricle, left atrium and left ventricle. Now, I'm also going to draw a couple of other things that are important and really closely related to the heart. So up here, I'm going to draw a pair of lungs because our lungs are very closely related to our heart. And down here, I'm also gonna draw a little dude to represent our body because our body is also closely related to the heart in terms of blood flow and how all of that works. Now, the point of the heart existence is to take blood and to pump it around to different parts of your body and to get blood and send it to your lungs. And we have to understand how all that works understand why the heart is so important. So let's take an example. We're going to talk about deoxygenated blood. So what that means is it's blood that has been delivered to a certain part of our body. And once that part of our body uses it we take up all of the oxygen to use it for energy. And once we've used that oxygen up, we're going to send it back to our heart as deoxygenated blood. All right, so in terms of how we're going to get it back to our heart, our deoxygenated blood from the upper half of our body is going to go into the heart into the right atrium through something called the superior vena cava and deoxygenated blood from the bottom half of our body is gonna go into the heart through something called the inferior vena cava. All right, so lets the label those together, superior and inferior vena cava, all right. Now we're gonna have one other way for blood to get into the heart and that's actually going to bring deoxygenated blood from the heart itself that the heart has used oxygen up with. So there is gonna be a little dot here that's gonna represent something called our coronary sinus. And that's important because that again is another way of bringing deoxygenated blood into our heart that the heart itself has used. All right, so through all of those three different ways we bring deoxygenated blood into the right atrium of our heart. Now we need to get that blood from the right atrium to the right ventricle. So how are we gonna do that? We're gonna do that through a valve going from one atrium to one ventricle. All right, so let's draw out that. I'm drawing that valve with three cusps. That is important because it will differentiate it from a different type of valve. We're going to call this try like three in because it has three cusps. We're going to call it a tri cuspid to valve. Now this is one of the atrial ventricular valves and it gets a name because it connects the atrium to the ventricle. So this is also going to be called, our right atrioventricular valve It makes sense right? Okay, so remember that we're in this blue section so we've brought our deoxygenated blood from our right atrium to our right ventricle through a tricuspid valve. Now what good is deoxygenated blood for our body? It really isn't good at all right? So we need to find a way to get oxygen back into some of this blood so it'll be any good to us. Now, where do you think we're gonna send this blood to get oxygen? All right, if you guessed lungs you're right. So we need to get the blood out of our heart and bring it to the lungs. Now, the same way that we transferred it from one chamber to another using a valve, we're gonna use a different type of valve here. I'm gonna draw this valve right here represented by three circles. And that is going to be our pulmonary valve. And this is a type of semilunar valve and it gets that semilunar name by the way that it works and the way that it looks. We can look into some pictures in our session together just to review what that looks like, but just know that as our pulmonary valve for now. Now, if we're taking blood from this right ventricle up to the lungs what we're going to name it after is where it's headed which is towards the lungs. So I'm going to draw the attachment from the pulmonary valve as it's going up here towards the lungs that is going to be called our pulmonary trunk, okay? Now that trunk is going to split into two and it's going to go to both of our lungs. Now what those are called is our right and left pulmonary something. Now this is where our past knowledge comes to a test, okay? So remember we said we have arteries and veins, a goes away from the heart, veins comes back towards the heart. So what do you think this is gonna be called? Pulmonary artery or pulmonary vein? Perfect, if you guessed it, it is called the right and left pulmonary artery because artery starts with an a and a means away from the heart. Alrighty, so we did it. We took our deoxygenated blood and we brought it to the lungs. Now, if we have all this oxygenated blood from the lungs what good is that gonna do if it's just sitting there? So we have to bring it back into the heart. How are we going to do that you may ask? Well, we're going to do that by bringing it from the lungs back in the heart, through something called our right and left pulmonary veins. And those are veins because they're bringing blood back towards the heart, all right? Now all right, so it brought blood back into our left atrium suite. That is great. Now we need to bring it from our left atrium into our left ventricle. Now, how did we do that on the right side? We brought it from our right atrium to our right ventricle with something called a tricuspid valve. Now we're gonna bring it from our left atrium to our left ventricle through something that's very similar but there is actually just going to be two cusps. I'm gonna separate our little list of words down here. That is going to be called you guessed it just like this one was tricuspid this is going to be called bicuspid valve. And this is also known as mitral valve. And just like this is our right atrioventricular valve. This is going to be our left atrioventricular valve because it goes from the atrium to the ventricle. Alrighty, now, all right suite we got our blood in our left ventricle. It's all oxygenated from the lungs. That is perfect. Now, what do we need to do? What good is this oxygen and blood if we can't send it out to our body? It is no good, good answer. So, we need a way to send it out of the heart. Now how did we send it out of the heart on this side? Perfect, it was through a semilunar valve. We're going to do the same thing with a different semilunar valve on this side. And that it's going to be called our aortic valve which is another type of semilunar valve. And that is going to give a way to something called our aorta which is essentially gonna come from this valve and we're gonna talk in more detail about the aorta in a bit but just we're gonna call it just the aorta for now and that's gonna come all the way down, back to our body. Alrighty, so we did it. We brought our blood all through the heart. Now, what I want to review with you is essentially an overview of how that worked. I'm going to do that using some arrows. All right, so we're going to take blood cells from the top half of our body and from the bottom half of our body. Now, remember after we've used all these blood cells up, we use up all of the oxygen from them and we're sending them back from the heart or towards the heart, excuse me. So we're gonna bring blood from the top half of our body. And we're going to bring it up in through our superior vena cava, into the right atrium. We're gonna bring blood from the bottom half of our body and through the inferior vena cava into the right atrium. We're also gonna have deoxygenated blood directly from the heart and through the coronary sinus. Now that blood is gonna go from our right atrium through our tricuspid valve, into our right ventricle. Then from our right ventricle, it's going to go through the pulmonary valve, through the pulmonary trunk and into our right and left pulmonary arteries that's gonna bring it into the lungs. Now we're gonna take that blood in the lungs and we're gonna fill it up with oxygen and turn that deoxygenated blood into oxygenated blood. Once we do that, we're going to bring it back through the right and left pulmonary veins. Remember cause a is away, the veins is towards and we're gonna bring it into the left atrium. Now from the left atrium, we're gonna go through the bicuspid valve into the left ventricle. And now we have all of this great oxygenated blood. We need to figure out how to get it out of here. We're gonna take it from the left ventricle through the aortic valve, into the aorta and it's gonna make its way back towards our body. And that is all of the structures or the main structures that are attached to the heart and how the blood flows through them. All right, so now that we covered that, we're going to break it down a little bit further, and we're going to go into some more detail regarding the aorta and the branches off of it as well as a couple of different blood vessels that supply the heart itself. Alrighty, so let us draw the different blood vessels in the heart. We're going to start this out as we always do by drawing just the heart structure to start off. Now I'm gonna hold off on drawing the left part for just a moment 'cause I'm gonna draw out some cool vessels coming out of here first. All right, we're almost done. We have a few more vessels to draw here. The heart is only important if we realize what it does and what these important vessels are that extend out of it. All right, sweet. So we've got a bunch of these cool vessels here and oops, let me draw in the left side of the heart here. Bam, there we go. Let us also cut this into quarters like we always do. And let me add in a few extra vessels there Alrighty, so you know how we talked about the aorta in general, coming out of the heart from our aortic valve right there? We're gonna break that aorta into a bunch of different parts and we're gonna talk about the different vessels that branch off of it. So let's start with these little vessels down here. Now this is remember how we're transporting our oxygenated blood and our heart is only good if it can actually pump things. So. we are going to label the vessels that actually provide blood to the heart itself. Alrighty, so we're going to start off with a vessel we're gonna make bright pink over here. This is our left coronary artery giving blood to the left side of our heart. All right, we got our left coronary artery. What do you think we're gonna have on the other side? You got it. Our right coronary artery bringing oxygenated blood to the right side. Now we're gonna have a really important branch coming off of that left coronary artery and it's called our left anterior descending artery. And those are the most important blood vessels for you to know that actually give blood supply to the heart itself, okay? Now let's label the different parts of the aorta that we were just talking about before. We're going to label this first part here the ascending aorta, because it's part of the aorta that bring blood up for it's ascending. Now we have something called the aortic arch which is this arch right here. And then it's going to turn into our descending aorta. Now I'm going to draw something here. It's going to represent our diaphragm. And remember, 'cause we have that diaphragm muscle sitting in our chest and above the diaphragm, it's going to be our thoracic aorta because it's sitting in the thoracic cavity and then below will be the abdominal aorta because it's sitting in the abdominal cavity. All right, now lets label all of these different branches that are coming off of the aortic arch. The first one here, is going to be called something that is our brachiocephalic trunk. And the name is named that for a reason. It's going to bring blood up to outer arm, which is brachio, and cephalic remember means head so it's gonna help facilitate blood going to our head and our arm. Now the first branch off of that is going to be, let's find a color, here we go. Is going to be our right common carotid artery right here. And I'm just gonna abbreviate aa for artery and this like two artery right here is going to be called our right subclavian artery. And actually you know what, let's right slash left. Let's label our right and left so for reference, our right is here, our left is here and our left subclavian on this side is actually gonna be directly off of the aorta coming off right here. And the subclavian artery continues the end of border of it is a lateral border of your first rib. And then it'll turn into actual your artery but anyway, I just want you to know the direct branches which is the subclavian artery on the right and left side. Now I'm gonna go back and label this as right and left common carotid. So here is our right common carotid because it's on our right side and here is our left common carotid. And I'm just gonna draw a little cutoff point right here in gray. That's how we differentiate between our right and left side. So to review right and left common carotid, right and left subclavian. And we're gonna have another important branch off of both of those. And let's see, let's make that blue. We're gonna have a branch right here and a branch right here. And that is gonna be our right and left vertebral arteries. And remember we learned about those vertebral arteries before we learned about them. Do you remember what they travel through that we learned pretty a little earlier before the midterm? That's right, they travel in the transverse foramen of the cervical spine. So now you know where they come from. So this is the heart and the major blood vessels that come off of it leading to other important parts of our body. Now, up here, we talked a lot about things going into our arms, the descending aorta and abdominal aorta is gonna go turn into some other things that will give blood supply to our legs instead. All right, so we have one other part of the heart that I wanna review with you before we finish it. It's gonna be some stuff on the inside of the heart. All right, what are we gonna do? Like always, we're going to draw the heart again. The right side and the left side. You split it up or just another reminder this heart is actually tilted on the right side when it's sitting in the mediastinum. Now let's label these guys again just like always. Right atrium, right ventricle, left atrium, left ventricle. All right, so there is our heart. We're gonna label a couple of different things. This green part is going to be our inter meaning between, interatrial septum. That's essentially what's going to separate the two atriums. And we're gonna have the same thing down below for ventricles. That's going to be our interventricular septum. All right, so now we're gonna look at the inside of the heart so this is gonna be essentially a coronal cut and oh, a couple of other things I forgot that I wanted to mention. Two little things coming off The sides are called auricles and in them they have something called pectinate muscles. Now, if we're looking at that coronal cut of the heart, we're gonna draw our attention to some internal stuff. So what actually makes these valves work and the muscle work itself. Now let's draw. We're gonna draw some like squiggle part of the heart which actually really does look like a squiggle when you're looking at the inside. That's going to be called our trabeculae carneae. Now sitting on top of that is our little muscles that we have. You'll be able to see these pretty distinctly in the models if you look it up online. Those are called papillary muscles. So just for reference, this is gonna be on both sides but I'm only gonna draw it on the left. Now just so we have a little bit of a point of reference, here I'm gonna draw in our bicuspid valve. And the way to kind of remember that the tricuspid valve goes on this side and the bicuspid valve goes on this side here I'll draw the other one in, just for kicks. Tricuspid valve. You're gonna try something like clothes. You're gonna go try cool clothes on before you buy it. So blood is always gonna go through the tricuspid valve on the right side before it goes through the bicuspid valve because you have to try it before you buy it. Alrighty, so the point in me drawing that valve in is I wanna show you a really important connecting piece that plays a significant role in connecting our papillary muscles to that valve. We have some attachments and those are called chorda tendineae. Now this is all really important. These are all connected because our valves have to open and close to allow or inhibit blood flow from coming through from atrium to ventricle. What happens is, is these papillary muscles, I'm gonna write a little note, they contract to close valves. So these little guys, they contract, they pull on the chorda tendineae which are attached to the valves and when they pull on it they're gonna close those valves. So these are really important for the function of the heart. Now we went over the basic structure, the blood flow, the different branches of the aorta, and now the internal structures with this coronal cut of the heart and that will wrap up our discussion of the heart for today.