[Music] the heart needs its own blood supply because it does not have access to the oxygen and nutrients that's inside the heart passing through the chambers as the heart is pumping so the heart needs its own system of arteries veins capillaries to deliver blood to itself so that it doesn't die once you get past the really big arteries in the body blood flow is actually pretty smooth and pretty consistent but the heart beats right so really the blood coming out of the heart gets gets comes out of the heart in pulses in big bursts squirt squirt squirt like that so when the heart contracts when the ventricles contracts it forms a it it it pushes out a whole bunch of blood all at once out into your arteries but if we follow that blood through the arteries into smaller and smaller arteries at some point once we get far enough away from the heart into smaller arteries the blood does not pulse through through the rest of the body the way that it does when it comes out of the heart it's actually fairly smooth and consistent flow that is due to an effect called the wind Castle effect so a wind Castle is structure that you see up here in the picture so in the picture this is with this is with with water right so you have a water source here and you have a pump and this kind of a pump old style pumps and when when you're pumping water it comes out and spurts like blood coming out of the heart but with a wind Castle it's this this device right here that has an air bladder inside and so when you put these two together the pump pumps water and spurts but the wind Castle make sure the water coming out the other side is smooth and consistent and this is good let's say that if you're a firefighter right you don't want the water coming out of the hose in spurts it's a lot easier if the water comes out in a continuous stream that is due to this wind Castle effect and the heart here's how the wind Castle effect works blood flows into the heart Atria contract pushes the blood down into the ventricles but then the ventricle contracts forcing blood out of the heart so we're going to look focus on the systemic circuit here so when the left ventricle contracts it forces a lot of blood out of the heart out into the aorta okay so that blood there's already blood in the aorta right so when we push more blood from the left ventricle into the aorta blood flows through the aorta it pushes on the blood that's already there so we do push blood through the aorta but the pressure is so high that it causes the aorta and other elastic arteries to bulge open so now the left ventricle relaxes after its contraction and then those aorta and other elastic arteries snap back down to take their turn at pushing blood forward so we call this idea elastic rebound when elastic arteries like the aorta right they they expand when the heart pushes blood into them but then the heart relaxes the pressure drops and they snap back down to push more blood forward so in essence it's not just the heart that is pushing blood forward through the systemic circuit the heart takes turn takes turns with the elastic arteries due to elastic rebound and each of them are taking turns pushing blood forward through the body so heart pushes then the arteries push when they snap back down heart arteries heart arteries heart arteries and by alternating like this this ensures that Downstream of those elastic arteries in the smaller arteries and capillaries and in the veins this is going to make the blood move a lot smoother and a lot more continuously compared to how it's coming out of the heart now besides smoothing out the blood flow in the systemic circuit this is also important in coronary circulation this is how we the elastic rebound idea is how we can get blood fed back to the heart to feed the heart itself so when the left ventricle contracts and forces the blood out into the aorta this actually squeezes the osta that lead to the right and left coronary arteries and blood cannot flow to the heart but due to this wind CLE effect the idea of elastic rebound when the heart relaxes the osta open up and the aorta then snaps back down like a balloon and the it's the snap it's the snapping down of the aorta which will help push blood through the osta into the right and left coronary arteries so in a way the aorta is really what's pumping blood to the heart not the heart itself you do not need to memorize the list of all the coronary blood vessels I just incl included them here in the picture we focus on learning these in lab here's a picture of a real heart the blood vessels the arteries and veins though they they've had a red and blue latex die injected in they're not really this color but that just makes them stand out so you can see them on a real heart another type of circulatory system disease is what we call coronary artery disease CAD coronary artery disease in coronary artery disease what happens would be these coronary arteries either get partially blocked or completely blocked and that reduces blood flow anytime not just in coronary arteries but anytime a tissues or organs get reduced blood flow we call that aeia so what causes esea or cor what causes coronary artery disease that type of esia is when you get plaques that form inside like in the walls of the artery so if we look right here this is a normal this is a cartoon but it's a normal view of an artery we see how it's nice and smooth on the inside in a cross-section it's nice and smooth on the inside and really big and open to hold a lot of blood but then with when plaques form these plaques are deposits of cholesterol and fat that kind of build up in the wall and make the wall expand and push into the Lumen the inside part part of that artery so in cross-section we can see that there's a reduced area cross-sectional area in that artery due to the plaque formation and that causes esea one common symptom of having coronary artery disease where the the esema gets so bad is that you get you get pain right so we call this this type of chest pain angina pectoris pectoris like pectoral muscles chest okay so angin pectoris is this type of squeezing chest pain that can also radiate out to different parts of the body like arm back neck those areas those are what people often cight is a common sign of having a heart attack you get some squeezing chest pain maybe that shoots out into your arm maybe left arm neck jaw into your back it is different for different people so the whole left arm pain thing is much more common in men than women women often get that that radiating pain more into like the the neck type jaw area so just because your left arm doesn't isn't hurting doesn't mean that you're you're not having a heart attack it it it manifests differently in different people so the problem with esea is that if tissues cells organs aren't getting enough blood so oxygen nutrients and things like that then eventually the the tissues of the organ will die on top of that when you get plaques that form it also makes it more likely that you'll get blood clots that form on top of the plaques which can cause other problems so up here you see thrombi is plural for thrombus and a thrombus is a blood cloth that forms inside of a blood vessel which would only make matters worse so up here there are some scans of a heart a normal heart and a heart that has pretty pretty severely Advanced coronary artery disease so the nice bright colors that you see here in the normal heart picture that's good blood flow that you see how much blood is flowing through these arteries and how much of the heart here The myocardium the heart muscle is getting that blood flow but then over here you can see it's it's there's the color is running through the arteries it's not as it's not as bright red it's thinner right there's a lot of blockages going on in these in these blood vessels here and so you see The ventricle on this side it's like hardly getting any blood flow whatsoever so this is a severe restriction is the esia is gets too bad or happens for too long then you then the the tissue will start to die so this is what we call an infarction an infarction is tissue death due to lack of blood or due to esea if if it happens with your with your heart muscle that's called a myocardial infarction known as an MI or a heart attack and so this is what a heart attack is it's a myocardial infarction so parts of your heart muscle don't get enough blood it's es schic heart muscle dies the the bigger the the artery that gets blocked the larger the patch of heart muscle that dies there are a couple of different ways that we can test to see if someone is in the in the process of having a myocardial infarction or has had a myocardial in infarction and the reason you want to test for this is because there are other things that could happen in the body to make you feel like you're having a heart attack or to cause chest pain severe emotional stress reflux disease where some some stomach acid splashes up in your esophagus right indigestion so there other you know other things that could present like a heart attack so what we do is we test with we monitor the electrical activity of the heart so we call that an ECG an electrocardiogram where we monitor how the electricity is passing over your heart and causing it to contract or when heart muscle cells die they break open and they release enzymes that are unique to them to the heart muscle they release it into the blood so you can also do a blood test and look for the presence of these enzymes that should only be in normal heart muscle cells so how do we uh what do we do about myocardial factions because this is a major cause of disease and and death in the United States one thing we do is what we call risk factor modification right so you try to reduce or eliminate the things that we know increase your risk for forming plaques and causing heart attacks so don't smoke get your blood pressure down to a normal range watch have have a a decently healthy diet try to lower your cholesterol try to deal with your stress all right try to get some more exercise those kinds of things that that most most people are familiar with is is part of a healthy lifestyle if that doesn't work or maybe we you do both of these things at the same time there are also various types of drugs that we could use to try to treat coronary artery disease and and heart attacks so if it's if if you're trying to deal with the blood clots that form on the plaques we can have anti-coagulant medications that we can give there are drugs that can slow down the activity of the heart or how strongly the heart is is working there are drugs that can open up and dilate blood vessels to try to increase the blood flow to the heart if it's blocked and so there's various different types of drugs drug treatments that we can use to deal with coronary artery disease and heart attacks there are surgeries now your textbook calls them non-invasive surgeries I would I would say that they're minimally invasive we still have to cut into the body so two common types of surgeries that that are like minimally invasive anyway are called atherectomy and balloon angioplasty so here's an atherectomy it's basically like a plumber trying to put a a roto roter into a pipe to clean out the blockage so we thread a small tube through the blood vessel and at the end is this device that that can either vibrate or oscillate or spin around and that will help Munch up or clear up the plaque right so we just try to to to break it off another treatment is angioplasty followed by the placement of a stent so in this case we we we thread a tube into that artery the problem is the artery has to be big enough for us to fit the tube in many cases the arteries are too small for this to work so this only works in certain conditions certain types of arteries but if the arter is big enough we thread a little tube here and at the end of the tube is a balloon so we inflate the balloon inflating the balloon will expand the artery so that we can increase the blood flow and then around the balloon is this mesh material called a stent so when the balloon expands it expands the stent this this mesh this silvery mesh material here when you deflate the balloon and pull it out the stent remains behind keeping that artery expanded to try to keep the blood flowing properly so this is angioplasty that's the balloon part and the stent is this mesh part here that keeps the artery expanded if those arteries are very small or there are several of them that are blocked and this the atherectomy or angioplasty just won't work then another an alternative treatment is what we call coronary artery bypass graft most people refer to this as a bypass surgery but it's coronary artery bypass graft in this we will remove a piece of a blood vessel maybe from a the person's leg or something like that you remove a little bit of blood vessel somewhere else in the body that that you're okay without and then we connect one end of that removed blood vessel to a large artery in the body with plenty of blood flow the other end of that removed blood vessel gets connected to the other side of the blockage so let's say that there was a plaque right here blocking the blood flow and if there's a plaque right here in this little bit of red artery if this blood flow gets blocked from the plaque then Downstream of that right these areas here aren't getting blood right due to it's a schemi so then we just bypass this why it's called bypass surgery we bypass that plaque that blockage one end of the blood vessel here right blood flows here through the blood vessel the other end of the blood vessel after we put it Downstream or after the plaque after the blockage and so we can restore blood flow to those affected areas if we have only we only use one blood vessel to bypass one area that's a single bypass if we use two blood vessels to bypass two blocked areas a double triple quadruple so single double triple quadruple bypass surgeries that just refers to the number of blockages we are bypassing with this type of surgery there are many risk factors s for coronary artery disease and heart attacks a lot of it is lifestyle smoking hypertension high cholesterol diabetes age well age isn't lifestyle oops sedentary Lifestyles not exercising okay those types of things um yes there are genetic predispositions to it as well you cannot fight genetics at at this point in time so sometimes it just runs in families and you know you can you can not smoke and you can eat a good diet and you can exercise and all this but you you still could be at a higher risk due to that genetic predisposition but a lot of it is lifestyle