Heart disease and stroke
Heart disease and heart attacks Basics of heart disease, heart attacks, heart failure, angina, cardiac arrest. Special thanks to Edward J Perper, MD for help in clarifying certain aspects of this video. Licensed under CC-BY-SA
Heart disease and heart attacks
- 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.
- That is blue over here in this diagram, because that blood does not have carried oxygen
- And it pumps that blood to the lungs where the blood gets oxygenated.
- And then it comes back from the lungs, depicted as red blood, now that it has oxygen in it.
- And then that oxygenated blood is pumped to the rest of the body.
- And I think also, most of us have the general idea that when people talk about heart disease or heart attacks,
- which we learn, are two different things, related but different things, that has something to do with the clogging of arteries.
- so when I was a kid and I first learnt about the clogging of arteries.
- and I knew enough that the heart is all about pumping blood to the body.
- I assumed the artery that people were talking about these big arteries that were coming away from the heart
- to the rest of the body that somehow these things got clogged up.
- so let me draw that, different colour you can see
- so this was my ....this is what I thought
- people were talking about when they were saying clogging of the arteries
- and maybe when they got clogged enough, the stopped blood flow to the rest of the body somehow
- and that would actually kill the person. I want to make it very clear right now.
- 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. It itself needs oxygen.
- So you have these arteries right over here, the red tubes. Those are arteries.
- and then the blue ones are veins.
- They're taking the de-oxygenated blood away from the tissue of the heart.
- And these are called coronary arteries.
- And this one over here at least from the point of view of me or you looks like it's on the right.
- Or from the point of view of the person whose heart it is, it's on the left.
- This right over here is called the left coronary artery or LCA.
- And this right over here in red is called the right coronary arteries or the RCA.
- And so when people talk about arteries getting blocked or getting clogged,
- they're talking about the coronary arteries.
- They're talking about the things that supply blood to the heart.
- So let's zoom in on one of them....Maybe we can zoom in right over here, that part of the artery.
- That's the tube....clear where I am zooming in. I am zooming in right over here.
- So over time, I am not going into the details how this happened. It is subject for another video.
- You can have these plaques build up along the walls of the artery.
- So over time if a 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 lipids, so things like
- fat, cholesterol and also dead white blood cells,
- which is this kind of messy substance right over here. This is what we call a plaque.
- And the formation of these plaques that obstruct the actual blood vessel, that actually obstruct the artery.
- We call it.....make it clear you see that. This is kind of tube over here. Let me draw the blood
- So this formation of these plaques we call atherosclerosis.
- So you can imagine if you have these things build up,
- it's narrowing the actual vessel that's supplying blood downstream from that obstruction.
- So it would be destructing the blood flow downstream right over there.
- In that general process we talk about the restriction of blood flow, that is ischemia that's happening.
- So ischemia is deprivation of blood flow and oxygen downstream from this right over there.
- That's what we call coronary artery disease, or heart disease.
- So this causes coronary artery disease, which is sometimes called heart disease.
- Coronary heart disease would be redundant, because coronary is already referring to the heart.
- This is also sometimes called heart disease. And so you can imagine if downstream the muscle tissue is
- not getting all the oxygen it needs, especially maybe when this person, whoever's heart this is,
- when they are exerting themselves, they need more oxygen. The heart needs to pump a little harder.
- If downstream the cells are not getting all of the oxygen they need,
- you can imagine that the heart maybe not able to provide all of the functions,
- whoever's heart this is, that they needed to do.
- And when that happens that's called heart failure.
- So heart disease is one of the causes of heart failure.
- Now I want to be clear, heart failure does not mean that the heart is stopping.
- That the heart is stopped and 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 well enough to provide adequate function for that person.
- The other symptom that actually might occur when someone has coronary heart disease,
- where they have obstruction or this ischemia
- or this deprivation of oxygen downstream from this obstruction, is that they might experience this kind of strangling chest pain
- That's called angina pectoris or sometimes angina.
- Very few people say the pectoris part. Sometimes you hear people say oh angina.
- Angina pectoris, which is really chest pain, angina literally comes from meaning this kind of strangling feeling,
- and pectoris is in the chest. This is strangling feeling in the chest.
- This is a symptom of heart disease. Now this is already not a situation you want to get into
- because already your body is not able to function as well as it maybe could be, as maybe it could.
- Sometimes as I might describe here is a plaque.
- Some plaques are actually unstable. These plaques just grow and grow and grow.
- It makes probably heart disease worse and worse, heart failure worse, and angina pectoris worse.
- These plaques are unstable. It can actually rupture.
- You can imagine all these blood flows, as plaque grows, the blood flows become a little turbulent around these plaques.
- It has to go really fast through this narrow section. It comes out turbulent on the inside and
- creates these friction and all the rest. At some point, you can imagine this plaque is unstable.
- It could actually rupture. Let me draw ruptured plaque over here....let me draw the same one....I am gonna draw the ruptured.
- Now this plaque has rupture. It got so big. Maybe the turbulent blood flow helped stimulate this and whatever else.
- For whatever reason, it ruptures.
- When it ruptures, now it sudden i am doing a simplification of the process right over here.
- Now the content of this plaque: the lipid, the cholesterol, the fat, the dead white blood cell.
- Now it sudden is exposed to the blood flow. in particular to the clotting factor in the blood.
- This is highly thrombogenic material. Thrombogenic, very fancy word.
- That just means, that tends to cause blood clot. Thrombosis is a blood clot.
- What happened is, as soon as this type of things happened, it can literally happen in seconds or in minutes.
- All the sudden you could have these clotting factors form a clot right over here right at the actual plaque.
- As this happens, it starts to really really really obstruct the blood vessel.
- Sometimes it can even completely obstruct the blood vessel.
- When it happens, you are significantly depleting the blood flow going downstream from there.
- You might even be shutting it off. When you do that, the cells downstream will no longer get oxygen.
- They will die. This right over here, is called an infarction. an infarct is actually a dead heart tissue.
- You can imagine when heart tissue begins to die, this is even worse than what we were describing with coronary heart disease.
- Not only coronary heart disease just is not getting enough oxygen, now they are actually dead.
- They are turning into dead tissue. This process of completely or almost completely depriving cells of oxygen so that they die, this is a heart attack.
- Let me completely obstruct this artery to make the point clear. this right over here is a heart attack.
- This is the primary cause of heart attack.
- It's less likely but sometimes a plaque could also go downstream, kind of form a thromboembolism.
- It would be this thrombogenic material, the clots around it.
- It would actually go and block the artery further downstream and be embolism.
- That can also block the artery and cause tissue to die. But the main cause is this intense clotting that can
- occur pretty quickly and completely obstruct the artery. There is one last word i want to touch
- sometimes mixed in with all the other words, that is cardiac arrest. That's because sometimes we use them in the same context.
- one thing can lead to another. Heart attack is not cardiac arrest. Cardiac arrest is the actual dying of the heart.
- What I just described in a heart attack, people can have a heart attack. They will have some part of their muscle tissue die.
- Some part infarct, that's what they called myocardial infarction. Myocardial means the tissue of heart or the muscle of the heart that's dying.
- Sometimes it is called myocardial infarction. That is not cardiac arrest.
- Cause you can have some of your heart tissue die and you can survive. Your heart would be impaired.
- But you will continue to live. Cardiac arrest is literally your heart stopping.
- This would obviously cause someone to die. If you have a bad enough heart attack,
- if you have enough of the tissue get starved of oxygen so that it dies, infarction occurs.
- Then it could lead to cardiac arrest. It always won't lead to cardiac arrest.
- Frankly, heart attack is not the only thing that can cause cardiac arrest.
- I also want to once again differentiate cardiac arrest from heart failure, because they sound the same, sound like heart is failing.
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