Lecture 1 - Introduction to the Cardiovascular System

so I thought to begin our series on cardiac Anatomy and cardiac physiology I thought I'd do a very quick video just looking at the basics of the heart so in order to understand the basics of the heart you need to realize that the heart is just a pump okay now that means that when the heart contracts it will force blood Judith's muscular contraction out and will pump it somewhere in the body now you'll find that when we look at the heart that it's actually split into two sides you have a left heart right left side of the heart or a right heart right hand side of the heart and you find that the left-hand side of the heart deals with oxygenated blood and the right-hand side of the hunt deals with deoxygenated blood okay when that left-hand side of the heart contracts it pushes the blood out and feeds the tissues of the body and that's our systemic circulation when the right-hand side of the heart which has deoxygenated blood in it when that contracts it pushes the blood to the lungs to become oxygenated and that's the pulmonary circulation and we'll talk more about this in future videos but first let's have a look and see how this blood flow all works so I like to start off and very very simply draw what you picture to be some cartoonish drawing of the heart right that's basically what we all imagine now obviously doesn't look like that obviously doesn't look like what if you were to picture the heart you had more so draw it like that now approximately it's the size of your fist you'd put it at your sternum level except you move it a little bit to the left and then you twist your fist so that the line of your knuckles are pointing towards your left hip you find that the heart as you can see has a point at the bottom which we call the apex and that apex of your heart is pointing towards your left hip if you wanted to know where that apex at actually sits just on top of your diaphragm and if you take your two fingers and if you know how to count your ribs you can go to your fifth rib and then the space below that which is the fifth intercostal space towards the left hand of your stone so basically it's underneath your left portion of your chest and you can feel that fifth intercostal space and if you just take a second you should be out of field the apex of your heart contract and that's about fifth intercostal space so that's just letting you know where the heart is actually sitting it regards to your chest but what I want to do today is just focus on this cartoonish picture of the heart now when we have a look at the heart we know that inside the hardness four chambers so what you can simply do is just separate the holiday and this four chose as you can see but two at the top and two below okay now the Chamber's at the top they are called atria or individually they are an atrium atria atria now remember that when we look at these types of diagrams we need to know which ways left which ways right okay now patient left is going to be over here patient rights going to be over here so this is the left atrium that's the right atrium now below the atria we have ventricles we have a left ventricle and a right magical easy you need to know that blood will always flow from atria two ventricles okay so blood will always go down now you need to also remember that and I might as well draw this one is blown and the reason why is because as I stayed at the stuff the right hand side the heart deals with deoxygenated blood so let's draw those blue even though blood that's the oxygenated is not blue it's just a different shade of red but we draw it like that anyway so both atria blood will always enter the heart to the answer okay always so what you can draw then it's a blood vessel that and a blood vessel like that easy and blood will always exit by the ventricles so you draw two more okay easy now anytime a vessel goes towards the hunt is called a vein anytime a vessel goes away from the heart it's called an artery so these two arteries moving away from the heart these two of veins moving towards the heart now when you see this red blood you can see that it's oxygenated and where do we get our oxygen from from our lungs which means that this blood is coming from somewhere that's given an oxygen so that we can then go out which means that this vessel right here going towards the left atrium has just come from the lungs Kasich which means that the lungs has given this blood oxygen the blood comes back to the left atrium now if you want to know the name of this vessel it's easy remember that it is a vein okay so veins going to be in the name and it's come from the lungs and when we look at the lungs or refer to the lungs we often use the word pulmonary so this is called the pulmonary vein pulmonary vein so the pulmonary vein carries oxygenated blood from the lungs to the left atrium that left atrium will contract push blood into the left ventricle that left ventricle will contract and push blood out which means this is an artery now if it's oxygenated blood what do you think it needs to go needs to go to parts of the body that require oxygen which is everywhere so this vessel ultimately will send this oxygenated blood to all the tissues of the body so what you can do is you can right body enjoy this vessel coming down like that okay what's the name of this vessel this vessel is called the aorta and it takes oxygenated blood to the body now once this blood has made it to the tissues of the body will hand it some oxygen also hand it some nutrients glucose so forth and it will take from those tissues carbon dioxide and metabolic wastes which means that the blood on the other side here is deoxygenated right because it's just handed all that oxygen away now once this blood is deoxygenated and has carbon dioxide and has metabolic waste products there's no point delivering it to the tissues of the body because they just don't need it so we need to take this somewhere where do we take it well we take it back to the heart so you can draw this blood vessel coming back up to the heart because it's coming back to the heart it's a vein and we call it vena cava so this blood vessel is called the vena cava easy now once this deoxygenated blood via the vena cava returns to the right atrium right agent attracts pushes blood to the right ventricle and the right ventricle what does it do with this deoxygenated blood well it has no oxygen but it's got co2 that's pointless for our tissues we need to do something with it we need to get rid of the co2 and take oxygen and take oxygen and bring it into the blood so how do we do that well we need to send it to the lungs so when the right ventricle contracts it brings this blood up and sends it to the lungs here at the lungs it will give away the carbon dioxide and take the oxygen and then the whole pathway begins again this vessel going from the right ventricle to the lungs remember it's going away from the heart they get the a in a way means it's an artery and this arteries go into the lungs which I said we use the word pulmonary so this is the pulmonary artery simple so I recommend before you start drawing more difficult more complex pictures of the heart which we'll do in future videos I suggest you just your very basic images of the heart and just start to label the major or the great vessels associated with it and the respective atrium and vegetables in the next video we're going to have a look at section in the heart and we'll look at some of the internal anatomy of the heart and also in another video we're going to look at more complex external anatomical landmarks such as the anterior and posterior portions of the heart so in this video I'm going to show you how to draw a more detailed diagram of the heart and also labels some more details which we didn't go through and they're very simple basic heart anatomy video that I've just uploaded previously so let's first have a look remember heart is broken up into the left hand side right hand side of the heart I want you to picture that we've taken a heart and we've coronal II sectioned it so that we've revealed the four chambers inside that's how we're going to be drawing the heart today so let's first of all start off with the right hand side of the heart so you know that you're going to have an inferior and a superior vena cava and the inferior and superior vena cava connect with the right atrium and the right a trend you know pushes blood through to the right ventricle and that right ventricle pushes blood up through the pulmonary artery and this pulmonary artery bifurcates splits into two to go to the left and right one respectively okay if you look at the left-hand side of the heart what we can draw up first of all is the left atrium then we can draw the left ventricle and look enjoy the aorta coming off and the a order you're going to see it's gonna go around and in front the pulmonary artery and as it starts to move across like this you're gonna find that there's three superior branches of the aorta which we'll talk about shortly coming off okay Joe like that but now it's just one more thing we haven't drawn we haven't drawn any of the vessels so the veins that are coming in to the left atrium and I'll draw that in a second what I want to first of all draw is the muscle that lines the heart so if we're going to draw some of the muscle that lines the heart and what you're going to find first of all is that if we have a look at the muscles of a myocardium which is the heart muscle for the ventricles you're going to find that the thickness of the left ventricular myocardium is about three times thicker than the left ventricular myocardium I want you to think why that's the case because this left ventricle when it contracts it pushes blood up into the aorta and that goes to the whole body so it needs to be under high pressure the right ventricle when it contracts was it pushing the blood - it pushes it through the pulmonary artery to the lungs not very far away so it's not a high pressure system the left hand side of the heart high pressure system right hand side the heart low pressure system and in my blood pressure video I'll talk about this in more detail okay now let's draw up some very basic lines either side so there's left lung there's the right lung and what we're going to draw now are the final blood vessels that come from the lungs to the left atrium okay so I'm going to draw these in a row it's too that for the left lung and to hear from the right one so what you can see is that with these veins these pulmonary veins we have for pulmonary veins okay let's let's write a little list first of all what you're going to find is we have if we start with the deal to do blood that's coming back from the body if it comes back to the heart so I remember right hand side of the heart if the deoxygenated blood comes back to the right hand side of the heart from above the heart it comes down via the superior vena cava if it's coming back to the heart from below it comes via the inferior vena cava so let's write this as step one Duke's a generator blood it's coming back so let's write it down here one vino okay now just remember we could start one anyway because it's a circuit it goes all the way back around so we're just starting with deoxygenated blood at the vena cava this the oxygenated blood comes in to the right atrium which is going to be step 2 right a true okay that run a chicken tracks and pushes blood into the lap into the right sorry metric oh now point three is not the right magical because the blood must move through a set of valves okay these valves just like any other valves are one-way so these don't separate the right atrium from the right ventricle and you can see that they open down like this so the blood can move from the right atrium down into the right ventricle they open up when that right ventricle contracts and makes a lot of pressure all this blood pushes up and closes these valves now the valves on the right hand side of the heart which I'm gonna write here is number three these valves and separate the right nature from the right ventricle are called the tricuspid valves tricuspid valve okay then it moves into the right ventricle and then that right ventricle contracts and pushes blood up into the pulmonary artery but before it goes through the pulmonary artery it has to go through another set of valves so I'm going to put five here indicating this set of alves okay now this set of valves here I called semilunar valves and that's because they look like little presents little present motors okay semilunar now you'll find that there's three of these little presents placed here within the pulmonary artery if you look down into the pulmonary artery they look that little Nets because when the right ventricle contracts are pushes blood up under contraction pushes blood up through these valves when the heart relaxes the blood wants to come back down we do not want the blood to come back into the right ventricle so these valves catch it like in this and they are the semilunar valves but because we're on the right-hand side though the pulmonary semilunar valves okay then that blood moves throat into the pulmonary artery now this is the pulmonary trunk and you can say the pulmonary trunk bifurcates meaning it splits off into two pulmonary arteries so we can write six pulmonary trunk and then we can write seven pulmonary arteries okay now the pulmonary arteries are going to push this the oxygenated blood to the lungs which is number eight now you know that this blood has no oxygen but it does have carbon dioxide which means that as this blood gets some the lungs gives the lungs carbon dioxide takes oxygen okay which means now this blood becomes oxygenated it has to come back to the heart becomes oxygenated has to come back to the heart and how does it come back well it always comes back to the heart via veins leaves the heart by arteries back to the heart by veins because they're the lungs they're going to be called the pulmonary veins and you can see there are four one two three four pulmonary veins so this is step not pulmonary bags okay now this oxygenated blood enters the left atrium this is going to be step 10 left atrium left atrium will contract and push blood through into the left of ventricle but it must move through another valve similar valve to what's on the right hand side so not the tricuspid over here it's called the bicuspid or the mitral valve bicuspid or mitral okay then it moves through so let's go to being 11 moves through to the left of the ventricle which is 12 then that left ventricle contracts all that thick myocardium of the left ventricle contracts and forces the blood up into the aorta however just like when the right ventricle contracted and push the blood into the pulmonary artery it has to go through about us and again this semilunar valves pulmonary semilunar a otic semilunar so number thirteen of the aortic semilunar valves okay then it moves into the a order and that a or the will start to branch and branch a branch they owners going to the a auto sorry is going to branch so many times that it goes from this penis big thick elastic artery to smaller smaller arteries and smaller smaller arterioles which are less elastic but more muscular and then they branch even further to capillary beds we're at the capillary beds the different tissues get fed they give the oxygen they give the glucose and then what happens it comes back to the heart by the inferior superior vena cava now these three little outlets here I'll talk about in a future video where I highlight some of the most important arteries and veins of the body but just know that at the moment they are just branches of the aorta taking the blood somewhere that needs to be fed so hopefully this is something that you can draw by yourself and helps you label the important anatomical features of the heart hi everybody dr. Mike here I want to talk about heart muscle that we call the myocardium Myo means muscle car diem is referring to heart and what you can see is the heart muscle varies in width or throughout the heart specifically when we look at the ventricle so the ventricles are the two bottom chambers of the heart when they contract or I should say when the myocardium that surrounds these hollow chambers contract so there's the left ventricle there's the right ventricle you can see I performed a transverse section through this heart when they contract they push blood out of the heart now the left ventricle pushes that blood out via the aorta and the right ventricle pushes that blood out via the pulmonary arteries now what you can see here is the left ventricle and the right ventricle myocardium heart muscle varies in thickness now the question is why do they vary in thickness and the answer is because when that right ventricle contracts it simply needs to push blood by the side that is to the lungs so it doesn't require a lot of pressure doesn't require a lot of force but when that left ventricle or myocardium of the left ventricle contracts it needs to push blood out to the entire body that's the top of the head to the tip of the toes and that means it requires a lot of pressure and that's a lot of force and in order to do that we need a lot of muscle and that muscle contracts it squeezes like a tuba toothpaste it actually begins at the bottom and squeezes upwards and then it squirts that blood out by the aorta to the entire body this is important clinically because if somebody has a myocardial heart muscle infarction death that resulting death of the myocardium and it can happen anywhere throughout this my account and predominately happens at the ventricles because they push blood out to the body so we get the most notable most noticeable effects there and think about it if the death of the heart muscle happens on the left hand side it's could only going to have the worse effects because it means that heart muscle can't contract deliver blood to the whole body person dies very quickly and the right hand side if it happens well it doesn't need to generate a huge amount of force to send that blood to the lungs so the left-hand side seems to be the most deadly side when it comes to a myocardial infarction and when this heart muscle dies it can just be a little bit of a heart muscle or go the entire width of the heart muscle that's called transmural if it goes through the entire width of the heart muscle or just a part of it you can notice these changes on an ECG also known as an EKG an electrocardiogram so this is a quick run-through of heart muscle hi everybody dr. Mike here in this video we're going to look at surface anatomy relating to the heart and also heart sounds that lub-dub lub-dub that we often refer to so first thing is we know that our hearts it's within our chest specifically an area termed the mediastinal and it sits behind our ribcage behind our sternum and we have our lungs either side now if you take your fist place it at your sternum then shift it a little bit towards the left and then tilt your fist so that you can draw a straight line down your knuckles to your left hip that's approximately the size and placement of your heart within your chest now what you can see is the top of the heart what we termed the base funnily enough that sits at around about the second rib and the apex will the pointy bottom that's pointing towards your left hip that sits at around about the fifth intercostal space now if you want to find this fifth intercostal space what you can do is go midclavicular get your left clavicle go midline down midline across move down towards your nipple and as you get to your nipple midclavicular feel the first intercostal space this is the first space between your ribs just below your nipple this is approximately the fifth intercostal space and if we just pause and feel that you should be able to feel your heart at that fifth intercostal space that's because the apex of your heart is beating against your chest wall so the base sits at the second rib approximately and the apex sits at the fifth intercostal space all right now what I've drawn up here is that heart sitting within the ribcage now what I've actually done is move the heart to sit more superficially so sits outside the ribcage but we know that the heart sits within and the sternum is protecting predominately the heart and you've got the ribs as well here's the clavicle or clavicles I should say a couple of things I want to refer back to the valves of the heart remember that you have two atria of the heart at the top two ventricles down the bottom blood always enters the atria and then the atria contract push blood down into the ventricles the ventricles contract to push blood out of the heart now in order for blood to move from the atria to the ventricles they need to move through valves either side the right-hand side from the atria to the ventricles have valves the left hand side has HRM ventricles okay and valves in between if we look at the right hand side going the right atrium to the right ventricle the velvet-- moves through something called a tricuspid valve now the tricuspid valve is this valve right here and like I said you're moving blood from the right atrium to the right ventricle through the tricuspid valve this is deoxygenated blood now on the left hand side we've got blood moving from the left atrium to the left ventricle through another valve called the bicuspid valve also known as the mitral valve and this is the Marshall valve here left ventricle the left atrium through the valve left ventricle all right so these are those two valves that we term the Atrio ventricular valves because they sit between the atrium and the ventricles now we need to talk about another set of Valve's called the semilunar valves now when those ventricles contract when the right ventricle contracts it pushes blood out of the heart to the lungs via the pulmonary artery and the pulmonary artery more specifically the trunk has a valve there called the semilunar valve it's called the pulmonary semilunar valve okay now the pulmonary semilunar valve you can see is sitting right here so when that right ventricle contracts it pushes blood up to go to these pulmonary arteries through the pulmonary valve all right pulmonary semilunar valve now on the left hand side when blood goes from the left ventricle out through the aorta it needs to go through a valve semilunar valve the aortic semilunar valve and that's this one right here okay why am I telling you about these valves it's because you can see say where they sit predominately and they sit put on the behind the sternum okay now this is important clinically because sometimes we need to listen to heart sounds why because there's two predominant heart sounds that lub-dub lub-dub lub-dub to the lub is termed the first heart sound and what happens is this as blood goes from the atria to the ventricles blood moves through the atrioventricular valves then the ventricles contract right and those valves are closed and blood turbulent blood dynamic blood moving blood hits those closed doors that closed a Chavan tricular valve doors which means the first heart sound is due to closure of the HR ventricular valves so when you listen to the first heart sound auscultation is the term that we use for listening so when you listen to these heart sounds and you listen to s1 you to whether there's any murmurs associated with closure of the AV valves perfect the second heart sound the dub is when the blood moves from the ventricles out of the respective arteries whether it's the pulmonary arteries or whether it's the aorta has to go through the pulmonary semilunar valve and the aortic semilunar valve and as it moves through they then close and as the blood wants to come back in the blood hits the wall turbulent blood hits the closed doors therefore the second heart sound the dub is due to closure of the semilunar valves all right and again auscultation of these valves can tell you whether there's a problem or a murmur a murmur is simply disrupted turbulence of blood through the heart now because they sit behind the sternum it's difficult to listen to it because it's muffling that sound it's blocking it but there's other parts of the heart we can listen to to hear those valves this is what this part of the lecture is about so if you want to listen to the mitral valve that's the valve that separates the left atrium from the left ventricle instead of going here behind the sternum you can go to the apex of the heart and I told you the apex of the heart sits at the fifth intercostal space on the left hand side right there perfect if you want to listen to the tricuspid valve you can stay at that fifth intercostal space move more medially towards the middle and you'll be able to hear the tricuspid valve what about the semilunar valves well the base of the heart sits at the second rib if you go to the second intercostal space on the left hand side you should be able to hear the pulmonary on the right hand side you should be able to hear the aortic so this is surface anatomy relating to the heart and this is the heart sounds as well in this video we're gonna look at the coronary arteries so remember the heart as a muscle it may contract and pump blood around the body and the lungs to feed it give it oxygen give it nutrients but remember the heart itself needs oxygen and nutrients and it gets it via the coronary arteries so that means the heart does not just pull oxygen and nutrients from within it actually needs its own dedicated blood supply again these are the coronary arteries now there's two major branches of coronary arteries there's the left and right coronary arteries and you can see that both of them come out at the trunk of the aorta here's the aorta here those three superior branches coming off and you can see that you've got the left coronary artery and the right coronary artery coming out now the important point is when the left ventricle contracts and pushes blood out via the aorta when that left ventricle relaxes called diastole systole is contraction pushing blood out relaxation is diastole in relaxation when the heart relaxes the blood wants to fall back down but it gets caught by what we call the aortic semilunar valves now when the blood gets caught in the aortic semilunar valves that's when the blood drains out via these coronary arteries this is important because it's very different to the way other vessels feed tissues they feed them under systole here the heart is being fed under diastole now as the left or right coronary arteries are receiving blood let's just focus on the left coronary artery okay now what we can see is the left let's label this we've got the left coronary artery and the left coronary artery continues down and as you can see there is the first major branch that comes off at the front now this front branch and anterior branch descends down and this anterior descending coronary artery which is what it's called goes down the interventricular septum now this is a septum this is an area that separates the left ventricle area from the right ventricle area has been the interventricular septum in actual fact you've got the two atria two ventricles you've got the atrial ventricular septum down here also known as the atrioventricular sulcus you can see that both the left coronary artery and the right coronary artery moves down the HR ventricular sulcus now with the left coronary artery we've got that first anterior descending branch that goes down the interventricular septum and it's called the left anterior descending coronary artery let's label that that's called the left anterior descending coronary artery the lad let's write the full word out left anterior descending coronary artery also known as the anterior descending coronary artery or the anterior interventricular coronary artery I know there's a lot of names but it's okay just remember the lad left anterior descending as we can and I'll tell you what it feeds in a second now as we keep going down the left coronary artery we spoke about that first branch that first left anterior descending you can see it goes all the way down to the apex of the heart and then moves behind the heart you can see that the lad moves behind the heart and feeds the majority of the interventricular septum and the majority of the left hand side the left atrium and left ventricles the muscle of that left hand side so the lad is very important as we continue with the left coronary artery we've got the circumflex artery so this is a branch called the circumflex which goes around the back circumflex and the circumflex coronary artery you can see moves behind the heart and feed some of the musculature behind the left-hand side of the heart then a branch of the circumflex here is what we call the marginal artery or the left obtuse will called the left marginal artery and you can see goes down the margin on the left-hand side of the heart feeding the musculature of that left ventricle okay so what we've got are these for the left coronary artery these are the three major arteries I need you to know it's the ladder left anterior descending the circumflex and left marginal most important point here is the lad because it feeds most of the left-hand side of the heart most of the left musculature of the heart it's the most important when it comes to a heart attack if there's a blockage of the lad most of left hand skillett ah will die off okay and this is going to lead to a my occuring faction with increased risk of death all right very important now if we look at the right coronary artery let's label that right coronary you can see that the right coronary actually flips behind the heart as well and you can see it moves behind the heart but before it moved behind the heart hit up in another branch and this branch is the right marginal artery so we had a left marginal artery now we've got I should probably write the correct side right marginal artery here's the left marginal go down the left margin here's the right marginal going down the right margin feeding the musculature of the right margin of the heart the left the right coronary which branches behind has an important branch at the back here this was the anterior descending this is the posterior descending now you can see that the posterior descending coronary artery may join together with the left anterior descending coronary artery and that's called an anastomosis an anastomosis is where blood vessels join together okay now this is common for us to have an anastomosis here from the posterior descending and the left anterior descending at the back of the heart it's more common in those people who have coronary artery diseases because if there's a blockage somewhere you want to increase the likelihood that the whole heart gets fed so coming together and joining used to your benefit okay reduces risk of myocardial infarction okay so what are the coronary arteries you need to remember for the left hand side you've got the circumflex the left marginal and the left anterior descending this is the most important for heart attacks for the right coronary artery we'll get the right marginal and the posterior descending and you may have an anastomosis at the back so this is a quick run-through of the coronary arteries you

Channel: Dr Matt & Dr Mike

Views: 64,910

Keywords: cardiovascular, system, cardio, heart, blood, movement, chambers, ventricles, valves, contraction, myocardium, sounds, coronary, arteries, pathway

Id: 5NRVOCBoDyc

Length: 37min 53sec (2273 seconds)

Published: Wed Jun 17 2020