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Now let's move on again to one final thing I want to point out,
好，我還要強調(diào)一點
which is I want to zoom in on the wall.
我們來看這個壁
So here in a grey box I'm going to kind of highlight what's going on in this wall
在這個灰色長方形里，我畫一下壁的構(gòu)成
and how many layers there are in this wall.
這個壁是由好多層構(gòu)成的
Let me draw out a little rectangle to correspond to that little rectangle I drew on the heart itself.
我用矩形來表示一下心臟上畫的這個小矩形
So there are 3 layers to the heart muscle.
心肌有三層
And actually I'm going to go through all three layers,
我給大家介紹一下這三層分別是什么
and we'll start from the inside and work our way out.
我們從內(nèi)層開始，逐層向外
On the inside you have what's called the endocardium.
最里邊的是心內(nèi)膜
I'm actually going to draw the endocardium all the way around here,
我畫一下心內(nèi)膜沿瓣膜，
it goes all the way around the valves.
這樣延伸
So now you've already learned that the valves now have endocardium.
現(xiàn)在大家知道，首先是心內(nèi)膜
It goes around the ventricle and, as I showed you in the beginning, also around the atrium.
包圍心室，剛我也介紹了，也包圍心房
It goes all the way up and covers both the right and left side.
把左邊和右邊都包圍起來
The endocardium is very very similar in many ways to the inner lining of the blood vessels actually
實際上，心內(nèi)膜跟血管內(nèi)膜是非常相似的
So it's a really thin layer, not a very thick layer.
都是非常薄的一層
And it's definitely, it's the layer that all the red blood cells are kind of bumping up against.
血管內(nèi)膜是紅細胞可以緊密接觸到的一層膜
When the red blood cells are entering the chambers of the heart,
一旦紅細胞進入心臟
the part that they're going to see is going to be the endocardium.
首先接觸到的就是心內(nèi)膜
So this is what it looks like,
就像這樣
and this is that green layer all the way around that I've drawn now.
就像我畫的這個綠色的膜
So if I was to draw kind of a blown up version, it might look like this. Right?
畫一個放大版的，就是這樣
It's a few cell layers thick.
這層膜只有幾個細胞的厚度
And like I said on the inside you have some red blood cells bumping along.
紅細胞可以緊密接觸到這層膜
So manybe this is one RBC,
所以這可能是一個紅細胞
this is maybe another one and they would bump into that endocardium.
這是紅細胞，它們可能會撞擊心內(nèi)膜
If you go a little bit deeper to that endocardium, what do you get to next?
或者來到這里，那么再向外是什么呢？
Next you get to myocardium.
下一層是心肌層
That would be, I'd say, the biggest chunk of our wall.
這是心臟壁中最大的一部分
And that would look something like this.
就像這樣
