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Now you may be wondering
大家可能要问
'How on the world do you get a layer that has a gap within it?'
为什么会存在一个间隙呢？
So let me actually try to show you what happens in a fetus.
我来画一下胚胎的情况
Let's say you have a little fetus heart,a tiny little heart like this.
假设这是胚胎的心脏，这时候心脏非常小
It gets a little bit bigger, like this.
然后慢慢长大
And finally it gets into an adult heart, something like that.
最后这是成人的心脏
This would be the adult heart, right?
这是成人的心脏大小
Well, at the same time that the heart is growing,
那么，随着心脏长大
you also have a sac, almost like a balloon. Right?
这里会形成一个囊腔，就像一个气球
This balloon actually begins to envelope the heart.
这个囊腔把心脏包围起来
This growing heart kind of grows right into the balloon.
心脏在气球状的膜内生长
This balloon starts going around it, like that.
膜把心脏包围起来
And you get something like this.
就像这样
Eventually, as the heart gets really big, you get something like this.
最后，当心脏成型之后，就变成了这样
You basically have this kind of inner layer of the balloon that's pancake dot.
气球内层
It doesn't even look like a balloon anymore. It's very flat.
不再像气球了，而是变平了
Then it folds back on itself, like that, and it comes all the way around.
然后自己向后翻折,像这样全部包裹起来
Now you can see why- even though it's continuous,
大家可以看到，这是连续的膜
I mean, it's not like it breaks, it is continuous here,
膜本身并没有破损
you can see how, if you actually just were to look at at chunk of it,
如果大家看其中的一部分
like we're looking at right here, you could see how it would look like a pancake.
比方说这里，大家会看到，这就像一张薄饼
On our heart it actually- it literally would be something like this, like a very thin kind of pancake.
而心脏就像这样，非常像一张薄饼
And I'm not doing a very very good job making it look thin,
我画的不是太薄
but you can imagine what it is,
大家想象一下就可以了
that it could look like if I were to zoom in on it, basically something like that,
如果我们放大来看的话，这里就像这样
where you have two layers that are basically just kind of turned in on themselves.
两层膜就像这样
Both layers put together are called your pericardium.
这两层膜就叫做心包膜
There are actually separate names for the two layers.
实际上，两层膜分别有自己的名字
For example, the layer that's kind of hugging up against the heart,
包围心脏的这层膜
this layer that I'm drawing now, this layer is called the visceral pericardium.
也就是我在画的这层，这个叫做心外膜
So you call that the visceral pericardium.
这层是心外膜
The name visceral, this right here would be visceral,
这是心外膜
the reason it's called visceral is because viscero- means organs.
前缀viscero-意思是内脏
So that's called the visceral pericardium.
这层膜叫心外膜
This outer layer, the one I'm drawing now, is called the parietal pericardium.
而这外边的一层是心包壁层
That's the layer that actually is on the outside.
也就是在心脏外层的这层
Let me label that as well. So that's this guy.
我标一下，这是心包壁层
That would be the parietal pericardium.
这是心包壁层
Now you can actually see the layers of the heart, the endocardium, myocardium and pericardium.
大家现在可以看到心脏的层次结构了，分为心内膜，心肌层，心包膜
And actually just to throw you a curveball, becasue I'm pretty sure you can handle it,
再给大家出个题目，相信大家能够解答
this visceral pericardium, another name for it, just because you might see it sometime, is the epicardium.
大家可能会看到，心外膜有别的术语名称叫epicardium(心外膜)
Sometimes you might see it, the epicardium.
大家可能会遇到
Don't get thrown off; it's really just the visceral pericardium.
不要混淆，这就是心外膜
It's just the outermost layer of that heart before you get to the parietal layer.
指的就是除了心包壁层以外，心脏最外面的一层
