If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:12:21

Heart disease and heart attacks

Video transcript

I think most of us know what the heart does in our body it pumps the blood and in particular it takes in the blood from the rest of the body and it's blue over here or in this diagram because that blood does not carry oxygen and it pumps that blood to the lungs where that blood gets oxygenated it gets oxygen and then it comes back from the lungs and then they depict it as red blood now that it has oxygen in it and then that oxygenated blood is then pumped to the rest of the body and I think also most of us have this general idea that when people talk about heart disease or heart attacks which we'll learn or two different things related but different things that it has something to do with the clogging of arteries and so when I was a kid and I first learned about the clogging of arteries and I knew enough to know that the heart is all about pumping blood through the body I assumed that the arteries that people were talking about were these big arteries the arteries that are coming away from the heart to the rest of the body that somehow these things got clogged up so let me let me draw that a different color you could see so this was my person this is what I thought people were talking about when they were saying clogging of the arteries and maybe once this got clogged enough it stopped the blood flow to the rest of the body somehow and that that would actually kill the person and what I want to make very clear right now is that is not what those are not the arteries that people are talking about getting clogged when people talk about heart disease or heart attacks the arteries that they are talking about are the arteries that actually provide blood to the heart remember the heart itself is a muscle itself needs oxygen and so you have these arteries right over here so these red the red I guess tubes that are depicted on this picture those are arteries and then the blue ones are veins they're taking the deoxygenated blood away from the muscle tissue of the heart and these are called coronary arteries and this one over here that least from the point of view of me or you looks like it's on the right but from the point of the view of the person whose heart it is this is on the left and so this right over here is called the left coronary artery or the LCA and this right over here in red this is called the right coronary artery or the RCA and so when we people talk about arteries getting blocked or arteries getting clogged they're talking about the coronary arteries they're talking about the things that supply the blood to the heart and so let's zoom in on one of them so maybe we could zoom in right over here so if we zoom in right over here that part of an artery that part of an artery that's the tube I just let me zoom in make it a little bit clearer where I am zooming in so I am zooming in right over there so over time and I'm not going to go into the details of how this happens that's maybe a subject for another video you can have these plaques build up along the walls of the artery so if you zoom in over time if the person doesn't have the right diet or maybe they just have a predisposition to it you can have these things called plaques form on the walls of the arteries and the plaques the material inside of them are our lipid so things like fat cholesterol and also dead white blood cells so it's this kind of it's this kind of messy substance right over here and this is what we call a plaque and the formation of these plaques that obstruct the actual blood vessel that actually obstruct obstruct the artery we call this let me make sure make it clear that you see that this is a kind of a tube right over here let me draw the blood draw the blood so this formation of a plaque we call atherosclerosis atherosclerosis a thorough atherosclerosis a flow atherosclerosis and so you can imagine if you have these things build up it's it's it's narrowing the actual vessel that's supplying blood to the rest to downstream to that downstream from that obstruction so it would be it would be disrupting the blood flow downstream so it would be disrupting the blood flow right over there and that general process that we talked about of that restriction of blood flow that ischemia that's happening so schema is a deprivation of blood flow and oxygen downs REME from this right over there that's what we call coronary heart disease or core or Internet actress AK ordinary artery disease or heart disease so let me write this down so this causes coronary coronary artery disease coronary artery disease which is sometimes called heart disease saying coronary heart disease would be redundant because coronary is also already referring to the heart so another way this is also sometimes called heart disease heart disease and so you can imagine if the downstream the muscle tissue is not getting all the oxygen it needs especially maybe when this person's whoevers heart this is when they are exerting themselves they need more oxygen the pump has the heart needs to pump a little bit harder if downstream these these cells are not getting all of the oxygen they need you could imagine that the heart maybe is not able to provide all of the functions that whoever's heart this is that they need it to do and when that happens that's called heart failure heart failure so heart disease is one of the causes of heart failure heart failure now I want to be clear heart failure does not mean that the heart is stopping that the heart is stopped and that the person is dead it literally just means that the heart is failing to do what it should be doing it's failing to provide the needs of that person so it's not pumping hard enough or it's not pumping well enough to to provide I guess you know adequate function for that person the other symptom that actually might occur when someone when someone has coronary artery disease where they have this obstruction where you have this ischemia this deprivation of oxygen downstream from this obstruction is that they might experience this kind of strangling chest pain and that's called angina pectoris sometimes angina very few people say the victorious part you'll sometimes hear people say oh he has angina so that's that could also lead to angina pectoris which is really just which is really chest pain and in China literally comes from meaning kind of strangling feeling and then the pectoris is in the so it's literally a strangling feeling in a chest and this is a symptom of of heart disease now this is already not a situation you want to go get into because already or your body is not able to function as well as it maybe could be as maybe as well as it could but sometimes so what what I've just described here is a plaque but some plaques are actually unstable so this plot could just grow and grow and grow and it would make probably the heart disease worse and worse than the heart failure worse than the in China pectoris worse but if this plaque is unstable it can actually rupture so you can imagine all this blood flow as this plaque grows the blood flow becomes a little turbulent around it the blood flow becomes turbulent around this plaque I'm drawing the blood kind of you know because it has to go really fast through this narrow section and it comes out turbulent on the other side it could create all these frictions and all the rest and at some point you could imagine that this plaque is unstable and it could actually rupture so let me draw a ruptured plaque over here so let me draw try to draw the same one but I'm going to draw it ruptured so now now this plaque has ruptured it got so big and maybe the turbulent blood flow helped stimulate this and whatever else but it's some of whatever reason it ruptures so it ruptures and when it ruptures now all of a sudden I'm doing a simplification of the process right over here now all of a sudden this the kind of this the the contents of this plaque the lipids because the cholesterol the fats the the the dead white blood cells are now all of a sudden exposed to the blood flow and in particular to the clotting factors in the blood and this is highly thrombogenic material thrombogenic very fancy word thrombogenic but that just means that it tends to cause blood clot so thrombosis is a blood clot so what happens is is as soon as this type of thing happens and it could literally happen in seconds or even minutes all of a sudden you could have these clotting factors form a clot form a clot right over here right at the actual plaque and as this happens it starts to really really really obstruct the blood vessel at all and sometimes it could even completely obstruct the blood vessel and when this happens you are your your you are significantly depleting the blood flow going downstream from there or you might even become you might even be shutting it off and when you do that the cells down flow the cells downstream I should say the cells downstream will no longer get oxygen and they will die and this is this right over here is called an infarction or they are so that is an infarction infarction an infarct is actually dead heart tissue and so you can imagine once heart tissue begins to die so then when the heart tissue begins to die this is even worse than what we were describing with coronary artery disease now not only were they with coronary artery disease they're just not getting enough oxygen now they're actually dead they're turning into dead tissue and this process of completely or almost completely are completely depriving cells of oxygen so that they die this is a heart attack this right over here so let me let me completely obstruct this artery to make the point clear this right over here is a heart attack this or this is the primary cause of a heart attack there's someone there's some it's less likely but sometimes a plaque could also go downstream and kind of form a thromboembolism so it would be a code it would be a clot it would be a it would be this the thrombogenic material that clots around it and then it would actually go and block an artery further downstream and be an embolism and so that could also block the artery and cause tissue to die but the main cause is just this this intense clotting that it can occur pretty quickly and completely obstruct the artery now there's one there's one last word I want to touch on because it sometimes is mixed in with all of these other words and that is and that is cardiac arrest and that's because sometimes they're used in the same context and they are these things can lead one one thing can lead to another but cardiac arrest a heart attack is not cardiac arrest cardiac arrest is the actual is the actual dying of the heart what I've just described in a heart attack people can have a heart attack and they will have they will have some part of their of their muscle tissue die some part in infarct and that's why they call it a myocardial infarction myocardium is is the tissue of the heart is a muscle of the heart and it is dying so they call it sometimes the heart attack is called a myocardial infarction that is not cardiac arrest because you can have some of your heart tissue die and you can survive your heart will be impaired but you will continue to live cardiac arrest is literally your heart stopping and this would obviously cause someone to die so cardiac arrest is literally your heart stopping so if you have a bad enough heart attack if you have enough of your tissue get get starved of oxygen so that it dies so that it so that it becomes it farc ssin occurs then you could lead it could lead to cardiac arrest but it always won't lead to cardiac arrest and frankly a heart attack is not the only thing that can cause cardiac arrest and I also want to run it once again want to differentiate cardiac arrest from heart from heart failure because they sound the same sounds like the hardest failing but cardiac arrest is the heart stopping heart failure is essentially just saying that the heart cannot provide all of the needs for the body