Cardio 1.docx

Transcript So in this series of lectures we are going to be discussing the cardiovascular system and to start with we will be going over the heart. So the end of this section, so the series of lectures on the cardiovascular system, we want you to be able to name, locate, and describe the structures...

Transcript So in this series of lectures we are going to be discussing the cardiovascular system and to start with we will be going over the heart. So the end of this section, so the series of lectures on the cardiovascular system, we want you to be able to name, locate, and describe the structures of the heart. So that's going to be things like our left and right atria, left and right ventricles, the different types of valves and the names of the valves, where they are, what their function is, and the heart wall structure. Right now that sounds probably quite foreign, but as we go through this will make more sense. Our heart is two pumps, so we have the left side and the right side, or the pulmonic and the systemic side, so just being able to say which side does which, and also how the blood flows through the heart and to those different areas. Describe as the blood passes through the heart whether it's oxygenated or deoxygenated and be able to kind of understand the concept of how our body uses the oxygen it goes back to the heart, goes through the lungs to get re-oxygenated and then goes back out to the body. So understanding what the level of oxygenation of the blood is as it's flowing through our body and through our heart. And then our heart itself has its own blood supply, so being able to name those vessels and also to be able to locate them on the heart itself. So for these series of videos we're going to be doing an intro to the cardiovascular system, just go over some terms, things like that. Then we'll do the anatomy of the heart itself, so the different structures, then into the anatomy of the heart wall. So this is sort of going a bit more microscopic, and then how the heart functions to pump blood around the body. So that's how they're going to the lungs, going to our body and then the blood coming back to our heart. So some of these terms and you will potentially hear some of these throughout different parts of the body, different body systems as well. So septum is a partition separating two chambers. So if you think about your nose, you have a nasal septum and that separates your left and your right nasal cavities. Often people will get your nasal septum paste, but in the heart we also have interventricular septums. So inter is between ventricles, ventricular, so between the two ventricles we have a septum. Coronary. So this word comes originally from corona which means crown or wreath and these are the arteries that surround the heart itself and supply the blood muscle there. Sometimes this might help to help you to if you understand the origin of the word or what the word means it might help you to remember the name of it. Oscultate. So if I ever say this is how we oscillate the heart or oscillate the lungs, it's when we're listening to the heart and lungs sounds usually with a stethoscope. So that's oscultation. Pulmonary or pulmonic, you might hear these words interchangeably but anything that has pulmonary or pulmonic is relating to the lungs. Systemic is the circulation to our body, so I always think of the body as your whole system, whereas we have our pulmonary is relating to our lungs, our systemic is relating to our body. Parietal, so there's a couple of terms here, these are also terms that you'll hear throughout other parts of the body, parietal. So often we'll use parietal and visceral as terms relating to connective tissue layers that line body cavities. So parietal is always parietal means wall. So this is going to be the layer that's usually on the outside so it might be lining the body wall in the cavity where an organ sits or it might be on the outer layer of of a lining of an organ whereas visceral is our viscera are our organs so any of our internal organs if you hear the term viscera usually it probably relates probably we use it more in regard to abdominal organs but your viscera your heart and lungs are also viscera as well and so any visceral layer is going to be firmly attached to the organ itself. So these terms once again will probably make a bit more sense as we go through. So our cardiovascular system, often cardiovascular system will be shortened to CVS. It's a much quicker way to write it. So if you see that, then that's what we're talking about. So with our cardiovascular system, our anatomical structures are our heart itself, and then the blood vessels, which are our arteries and veins which extend around the body. We also have the blood that is contained within the heart and the blood vessels. We have two sides to the heart and if whenever we look at pictures, so if we look at this picture you'll quite often see right, parts of the heart are actually on the left and the left parts are on the right and every time we look at a picture of a heart we're going to see that mirror image view. So basically what we're doing is we're looking at if we were looking at an animal front on our left is going to be our right and our right is going to be their left. So every time we look at a heart it's always going to be flipped around so it's like we're looking at the animal that this heart has come from. So remember that whenever we're looking at the pictures of a heart. So we have two sides or two pumps in our heart, One side pumps blood to the body and that takes oxygen and nutrients to our tissues. So remember our cells, our mitochondria need nutrients and oxygen to create energy for ourselves to do things. They'll also need building blocks to do things. So that's our left side of our heart pumps blood out to our body so that our tissues can receive what they need. Then once they use all of that oxygen and nutrients up and they produce waste products then it's going to come back to the heart and it needs to be filled up again so we need to get rid of the carbon dioxide and take in oxygen again and so that the other side of the heart pumps blood to the lungs so that we can get rid of that carbon dioxide and take up more oxygen into our blood again. And then it'll go back to the heart to be pumped to the body. So it's just this big cycle going around. Sometimes you might hear us talking about a great two vessels and these are usually the big arteries and veins that are leaving or coming into the heart itself. So they're the biggest blood vessels. So on this diagram here we can see that this one is one here, this is our aorta, We've got veins here, we've got another artery here and some more veins here. So those are our grape vessels. It's one that our aorta is coming down here. So the bottom part here is just a continuation of that. Arteries, So arteries are blood vessels that are leaving the heart. So if it's a blood vessel that's pumping blood out of the heart, it's always going to be called an artery. And if it's bringing blood back to the heart, it's always going to be a vein. And if we talk about oxygenated and deoxygenated blood, we go into this more in the blood lectures. The red blood cells in our blood carry our oxygen. So if we say we've got oxygenated blood it just means that our erythrocytes or our red blood cells are carrying oxygen. If we're talking about deoxygenated blood it means those erythrocytes or red blood cells have given up their oxygen to the tissue so they no longer have oxygen. So why do we need our cardiovascular system? So it's really important because as we said before our heart it pumps our oxygenated blood and which has our red blood cells with the oxygen attached to it. It also contains water for keeping our tissues hydrated, electrolytes, nutrients. It returns waste products to be eliminated and also has white blood cells for healing and inflammation, for protecting our body, those sorts of things. And so our heart pumps this blood all around to all the tissues and removes the waste products. So it's really important. Then it returns the deoxygenated blood with the waste products back to the lungs and to other organs that can excrete or get rid of any waste products. And then it will be replenished again to go back to the tissue. So as we said earlier our cells need the oxygen to produce energy and when they undergo their cell processes they'll produce carbon dioxide as a waste product and we need to eliminate that. If they, if it isn't eliminated, you can get quite dire changes which can mean that your body won't function anymore. And it's also really important to understand anesthesia as well as other diseases. So we do regularly see heart disease and heart failure in clinics, but probably more on a day-to-day basis, you'll be monitoring and participating in anesthesia of animals and anesthetic drugs depress our cardiovascular system. So it's really important that we understand the normal so that once we get into our anesthesia we can understand what's happening with our body. If something's going wrong, what is it that's going wrong for that patient and how do we fix it? So if you're to be able to problem solve and understand what's happening, you need to understand the normal first. So our heart anatomy. So our heart is in the cranioventral thorax. So if we remember our terms, cranial is towards the head end, ventral is the lower part of the thorax, so it's at the front and the bottom of the thorax. So it's approximately between the third and the sixth to seventh rip and it has, so it's within the thorax and it has the lungs around it on the outside and then the ribs around that. So the apex beat, you might hear this term throughout your studies, the apex beat is just the point where we can feel the heartbeat the strongest. So if you have a pet whether it's a cat or a dog at home and you put your hand around the area where their heart is, so around that third to sixth to seventh rib and usually I just would put my heart flat against the body wall and you'll be able to feel one area where the heartbeat is the strongest And that's the best place to put your stethoscope is over that apex beat area, because that's where you're going to hear it the loudest. So, and that will usually be around the fifth intercostal space. So remember, inter is between, costal are our ribs, so it's the fifth intercostal space. Often what you can do though is just have the patient in its normal position and usually the heart will be sort of just behind or just under the elbow. So usually what I will do rather than counting the ribs because that would take quite a lot of time when you're in practice. I will have the patient's elbow where it would normally sit, stick my hand kind of underneath there, feel for the Apex beat and then put my stethoscope there. For some of your pets, I know Lauren, who you'll have anesthesia, she has a whip at, and you can see his apex beat. When he's laying down and sleeping, you can see his heart beating because he is quite lean. He doesn't have a lot of fat, so you're able to see it really in really short coat as well, so you can see it really easy. So some of you might have an easier time than others to find heart rates. So these are our normal heart rates for our patients. We usually kind of say normal and averted brackets because it really depends on what is happening with your patient. If you've got a patient that's at rest they will probably have a much lower heart rate than if they're really stressed in a clinic. Sometimes if they have diseases it will go even higher than that so obviously that would be outside the normal range but you can see there is quite a large range for these. And you might have a dog who is a large breed dog who is relatively fit and they might have a slower heart rate when they're at rest at home. They're not stressed. They're sleeping so they don't need a lot of blood and oxygen to be pumped around their body so they might even have a lower heart rate. It doesn't necessarily mean it's abnormal. But in the clinic, this is probably, probably we would expect to see these values in our patients. I've put down here, if our patients are anesthetized, then obviously these are going to change quite a bit because as I said our anesthetic drugs depress our cardiovascular system so they slow everything down, they stop it working as well so these values will be quite different under anesthesia. So some directional terms and these will be important for in the lab. So we have our base which is the widest part of the heart and this is going through our apia. Then we have our apex which is the smallest part so the tip of the heart and that's going to be where the tips of our ventricles are. I kind of think of it as an upside down pyramid. If we had this as a triangle we flipped upside down the piece is usually the widest part, the apex is the tip so what our heart is just being flipped upside down. Just a reminder about those directional terms, so cranial is towards the head of the animal, portal is towards the tail of the animals, we use some of these terms with naming our buffessals, and whenever we look at pictures in the heart it's always going to be a mirror image so our right is on our left and our left is on the right and when we dissect our heart as well we're going to hold it that way around so that the right is on our left side. So heart chambers, there are four heart chambers. There's two atria or atrium would be a singular, so if we're talking about one it's an atrium. When we're talking about pleural it's atria and then we have two ventricles. So our atria are these smaller chambers up the top, one and then we've actually hidden by this. So here we've got an atrium here and an atrium here and then we've got our two ventricles. So these are lower down, the chambers are our ventricles. And we have some valves separate from our ventricles. And all of our heart chambers, so for our atria and ventricles, there is cardiac muscle in the wall and that's what enables our heart to act as a pump. So when that cardiac muscle contracts, it pushes blood forward through the blood vessels or through the heart to be passed on. So cheers, so they receive blood either from the body or the lungs. So they always receive blood from outside of the heart when they relax. So when they relax, they fill up and they'll be filling up from blood from outside the body and when they contract both of them will pump blood into the ventricles. So they receive blood from outside the heart when they contract they push blood into the ventricles. On our right side, this receives blood from our body. So if we remember our blood has been out to our tissues, it's gotten rid of its oxygen, it's collected carbon dioxide, and it's going to be coming back into the heart. You can see it's kind of often a blue colour and that represents our deoxygenated blood. So this is going to be deoxygenated from the body coming into our right atrium. Then when it contracts it'll go into the right ventricle. And then our left atrium, you can see this is nice and red. So this is received blood from the lung. So our lungs, when we breathe in, we breathe in oxygen, we pass our oxygen into our red blood cells and it's going to then go into our left atrium. When that contracts it's going to plug into the left ventricle. So we then move on to our ventricles. So remember they are at the peaks of the heart, so the pointy part of the heart. And we have left and right sides. And they are divided into a ventricular septum. So remember, the inter is between the ventricles and its septum, so it's a dividing wall. So that's our interventricular septum there. And our ventricles always receive blood from the atria and then when they pump, when they contract, so when that cardiac muscle in our ventricular walls contracts, It pushes blood out through our great vessels. So from our left ventricle, so remember this is our red side, so that's going to be our oxygenated blood, that's going to go up our aorta and that's going to go to the body. Our right side you can see this is kind of purpley colour so this is our oxygenated blood so that's going to need to get some oxygen so that one when the ventricle contracts it's going to go out of our pulmonary arteries to our lungs. So remember anything with pulmonary in it means lungs. So when this contracts it's going to go up to our lungs. Then it's going to click the oxygen, come back into our left atrium. It contracts, goes into our left ventricle. It's nice and oxygenated here, so that's going to go to the body. You can see we'll do this cycle quite a few times throughout the set of lectures. So as you saw in the previous pictures, we've got heart valves. And the function of all of the valves is to prevent backflow of blood during the contraction and relaxation of our heart. And what that means is that it prevents the blood from flowing backwards. So everything comes from our body into our right atrium. If that contracts and it pushes blood into our right ventricle, if there wasn't something stopping it here, When this contracted it would probably just go straight out this way. So that way we have this valve which then closes so that when this contracts it always goes forward into the pysilves. And our valves are made up of leaflets or cusps and that is how some of our valves are named but you can sort of see there's leaflets or cusps and this is probably part of the same one here and there are two locations of our valves. We have atrioventricular valves, so if we look at that word, atrioventricle, so these are the valves that go between our atria and our ventricles, and found between our atria and our ventricles. And then we have another type of valve called our semi-lunar valve. If we look at that word, semi means like part, lunar means moon. And if we have a look at this picture here, this is kind of like a half moon or if you know like you know it's not not a full moon shape if you went out halfway through the moon cycle and these are valves that are in the arteries that leave the heart so we have our a pulmonic valve so in our pulmonary artery and there's a little one hidden in here as well, which goes into our aorta. So we have two lots of valves, our atria ventricular valves between our atria and our ventricles, and our semilunar valves, and there are now arteries that leave the heart. Oh, So this is a picture. So if we look at this, it's kind of like a half moon, a semi-luna shape. And then if we compare it to these, this is just a diagram, but these, this one's in our pulmonary artery, this one's in our aorta. You can see that these parts of the valve look like half moons, four-part moons. So our valves do have names and it is important to know the different names because quite often disease will occur in certain areas and if we want to understand a patient with heart disease, what's happening there, then we need to know the names of the valves. So on our right side, so in our, if we start with our atria ventricular valves, on our right side, so between our right atrium and our right ventricle, we have tricuspid valve. So if we look at that, tri means three, cuspid is cusps. So this valve has three cusps. So our right side is our tricuspid. On our left side, We have our left AV valve or left atria ventricular valve. This one has two cusps and it Is also known as the bicuspid the most common term that we call it is the mitral valve. I've left out a cuspid so it's one less thing for you to learn because in practice we really just call this the mitral valve. So we have the tricuspid is the right atria ventricular valve and our mitral valve is our left atria ventricular valve. And then our semilunar or our half moon valve, These are in our arteries leaving our heart. So we have our aorta and our pulmonary artery, the two we go over these in a bit more depth soon and these ones are named abezia. So these valves are used to prevent backflow so when our ventricle contracts it's going to push blood into our pulmonary artery and when it relaxes it's kind of going to suck blood back. So we want it to take from our artery, we don't want the blood to go into the artery and then come back into our ventricle. So it stops back flow from our artery into our ventricle. These ones are named much easier. So our valve in our pulmonary artery is our pulmonic valve and our valve in our aorta is our aortic valve. So those are easier to remember. So we have our atrioventricular valves are our tricuspid on the right, mitral on the left and then our semilunar valves are our aortic valve and our aorta and our pulmonic valve and our pulmonary artery. Let's have a little video here that goes over how the valves work. So definitely recommend checking that one out because you can then have a visual and sort of see how the valves all work together. So the next structure that we're going to be looking at is our cordae tendinae. So if we kind of look at this, this word or this name, we can kind of break it down. So cord, so they're going to be like cords tendinae, it's tenderness. So they're kind of like cord like tendons. And so when we look at the heart, if we kind of can look at that name and figure out what the description means, we probably can figure out that it's these parts here that we're talking about, these stringy cord-like tendons. And they run from valve cusps down to polyurethane muscles down here. So they just help to support part, oh So I kind of think of these as like guy ropes on a tent. They don't make the valves work but they just help to prevent them from everting or the the valves from not working when under a lot of pressure from the blood flowing through the heart. So these are only in our atrioventricular valves, not in our semilunar valves. You'll see that when we dissect the heart and they're attached to these papillary muscles. So papillary, If we look at the word that means nipple and when you dissect your heart you will see that this is a little raised area on the inside of the ventricle and these are muscles that can contract a little bit but they don't really sort of pull on those heart valves. It's just once again it's that stabilizing effect to help prevent the valves from flowing backwards. So our blood vessels, we go into more depth with this in the next lecture but we will discuss it a little bit here so that we sort of understand the basics. So arteries always carry blood away from the heart. So arteries are away and they usually carry oxygenated blood. There is one exception for each of the arteries and veins that we need to know about. So we'll go over those shortly. But most of the time, our arteries will carry oxygenated blood away from the heart. Our veins, these usually, almost always, once again there's one exception we need to know about, carry deoxygenated blood towards the heart. So veins are towards the heart, arteries are away from the heart. So the exception are our pulmonary arteries and veins. And this is because when we look at the structure of our heart. So we have our deoxygenated blood coming back into these veins here, into our right atrium, our deoxygenated blood is pumped into our right ventricle. This needs to be oxygenated. So remember our right ventricle, when it contracts, it's going to send blood out through the lungs to get oxygenated. So it still has to leave the heart so that's going to go out through our pulmonary artery.