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本集视频介绍了心脏中的膜层结构和概念名称，帮助观者熟悉心脏的构造和工作原理，巩固基础知识。
n. 印章，封条
n. 海豹
v.
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- So you're probably feeling pretty comfortable with the diagram of the heart,
- 大家已经熟悉了心脏的构造图
- but let me just go ahead and label a few things,
- 这里我们再介绍一些名词
- just to make sure we're all on the same page.
- 加深大家对心脏构成的理解
- Blood flows from the right atrium to the right ventricle,
- 血液从右心房到右心室
- then it goes to the lungs and then the left atrium to the left ventricle.
- 然后进入肺，而后进入左心房，回到左心室
- So that's usually the flow of blood.
- 这就是血液流动路线
- And one of the things that keeps the blood flowing in the right direction we know is the valves.
- 而保证血液顺流，方向不出错的就是瓣膜
- Two of the valves I'm actually going to name, I'll give you new names,
- 给大家介绍两个瓣膜的新术语
- something slightly different from what we've been referring to them by
- 跟之前介绍的略微不同
- These are the atrioventricular valves.
- 这些都叫房室瓣
- You can take a guess as to which ones I'm referring to.
- 大家可以想一下，房室瓣指的是哪些
- Atrioventricular valves are the two valves between the atria and the ventricles.
- 房室瓣指的就是心房和心室之间的两个瓣膜
- One will be the tricuspid valve and the other the mitral valve.
- 一个是三尖瓣，一个是二尖瓣
- And just to orientate us:
- 标记一下
- this is the tricuspid, the T; and this is our mitral, our M.
- 三尖瓣用T标记，二尖瓣用M标记
- And the atrioventricular valves, these two valves
- 大家看这些房室瓣
- if you look at them, they're both kind of facing downwards.
- 看起来是面朝下的
- And one of the things that you might be wondering is
- 大家可能会想
- 'How is it that they aren't just flopping back and forth?'
- 为什么这两个瓣膜不会被血液冲得前后运动呢？
- And these valves in particular have a very interesting strategy,
- 这些瓣膜，有一个特征
- and that is that they're actually tethered- they are tethered to the walls.
- 它们其实是附着在心脏壁上的
- So they're held down here, like that.
- 像这样
- And they have on the other end of those tethers, a little muscle there.
- 另一端也有一小块肌肉附着在心脏壁上
- Now this makes perfect sense if you think about it.
- 大家想一下，这是非常合理的
- Because the ventricles are very strong, right?
- 大家都知道，心室是非常有力的
- We know the ventricles are really really strong.
- 是强有力的
- And so if the ventricles are squeezing,
- 如果心室挤压室内血液
- there's a good chance the blood is going to shoot up in any direction it can go. Right?
- 那么很有可能血液要向各个方向流散
- It's going to go back perhaps through the mitral valve,
- 可能会通过二尖瓣
- it can go there, or it'll go through the tricuspid valve, if it can go there.
- 又或者可能的话，通过三尖瓣
- But the reason that it won't, is that these papillary muscles are basically kind of sending out little life lines,
- 但之所以不会逆流，就是因为这些乳突肌
- these chordae tendinae life lines to keep the valve from flipping backwards.
- 这些腱索阻止了血液回流
- So these chordae tendinae, these cords are important for that reason. Right?
- 所以这些腱索是非常重要的
- They keep the valve from flipping backwards.
- 阻止了血液的回流
- So these are all the chordae tendinae and these are the papillary muscles
- 这些是腱索，这些是乳突肌
- And these are particularly important and we can tell for when you're trying to make sure that the ventricles don't screw up the valves.
- 这些是非常重要的，确保心室血液不会回流
- And now let's say that by accident our ventricle was just too strong, too powerful,
- 假设心室力量太大
- let's say it broke one of these cords.
- 假设把其中一条腱索拉断了
- Let's say it broke this one right here.
- 假设把这条拉断了
- And that's because our ventricle was just forcing too much blood back and it just snapped the cord.
- 因为心室要把血液全部挤压出去,可能拉断了一条腱索
- What would happen?
- 这时会发生什么呢？
- This would basically kind of start flipping back and forth,
- 可能瓣膜抵抗不了血液冲击了
- it would flip this way and this way.
- 可能会像这样上下移动
- And then on the next heartbeat, blood would start going the wrong direction, right?
- 那么在下次心跳中，血液就可能逆流
- Because this valve is not able to keep that nice tight seal.
- 因为瓣膜不能完全关闭了
- And so blood would basically kind of go this way when it wasn't supposed to.
- 所以血液可能出现逆流的情况
- And all of a sudden our flow of blood is now going in the wrong direction.
- 血液可能会逆流
- So the chordae tendinae and the papillary muscles do a really really important job in preventing that from happening.
- 因此，这些腱索和乳突肌起到了防止血液逆流的关键作用
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