Placeholder Image

字幕列表 影片播放

  • 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.

  • Cardiac arrest is heart stopping. Heart failure is essentially just saying that heart can not provide all of the needs for the body.

I think most of us know what the heart does in our body.

字幕與單字

影片操作 你可以在這邊進行「影片」的調整,以及「字幕」的顯示

B2 中高級 美國腔

心臟病和心臟病發作 (Heart Disease and Heart Attacks)

  • 216 18
    Grace Chien 發佈於 2021 年 01 月 14 日
影片單字