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可汗学院《保健与医学:循环系统》第2期:初识心脏(2)

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And one that kind of jumps to mind is carbon dioxide (CO2).
首先想到的是二氧化碳

So carbon dioxide is waste for this cell.
这个细胞代谢出二氧化碳来

So it's making some waste and for the moment let's imagine that there's no blood flow.
细胞产生废物，假设血管中没有血流

So, even though there's a blood vessel near by, really, no flow is happening, so I'll just write "no flow".
虽然这里有一条血管，但是没有血液流动

So as the little cell, little toe cells making waste.
那么这个脚趾细胞不断产生废物

That waste, let's draw as a little ball right here,
废物我们画成圆球的话

it's going to start accumulating, right?
废料开始不断累积

You're going to start collecting more and more of it since the blood is not really flowing.
废料越来越多，因为血液不流动

And it might start kind of getting all the way around our toe cell.
现在脚趾细胞四周都是废物了

So our toe cell is getting swamped, literally getting kind of covered by its own waste.
这样下去，脚趾细胞就被自己代谢的废物淹没了

And on the flip-side, is it getting oxygen or nutrients? No.
而另一方面，细胞获得氧气和养料了吗？并没有

It's not getting either of these things.
并没有得到任何氧气和养料

So, before very long,
那么，很快

I would say within minutes, our toe cell is thinking,
在几分钟之内，脚趾细胞就会发现

Well, this is not a very happy way to live!
这个生存方式不太合理

This is actually really very sad, this is awful.
是非常不合理

And if this continues the toe cell would die.
如果情况持续下去，细胞就会死亡

So, what a toe cell needs, and what every cell needs,
不光是脚趾细胞

and that could be a finger cell or a skin cell,
甚至是手指，皮肤细胞，所有细胞

or really any cell that's living, needs flow.
任何活细胞，都需要血液流动

Right? It needs this blood to be flowing nicely and smoothly.
需要顺畅流动的血液

And if there is flow, then you get a very different picture, right?
如果这里有血液的话，情况就非常不同了

If there's flow then all the sudden
如果血管中有血液

all this waste product is actually now lifted and taken away.
那么所有废物就被带走了

It's flowing away, and it's a little bit like having someone come by
被血液携带走了，这种情况比较像出门扔垃圾

and pick up the trash, then you don't have trash all over the house.
这样家里就不会堆满垃圾了

So then you have nice flow, and in return, oxygen and nutrients are delivered.
同时，如果有血液流动的话，也可以运送氧气和养料了

So this stuff gets delivered as well.
这些也可以被运进来

So, all of the sudden the cell is going to be very, very happy,
这样，细胞就会非常健康地生存了

and is going to be living just fine.
情况就会非常好

So, really if you want all of the cells in your body to be living just fine like this cell here,
那么，如果想要体内的每个细胞都保持健康的生存状态

you really want good flow throughout the body.
身体中的血液循环一定要顺畅

And so this is really point number one.
这就是第一点

Is that you really need, somehow, to have blood flow moving and pushing blood constantly throught the body.
心脏第一个功能使全身有持续顺畅的血液流动

So, to do this for billions and billions of cells
如果数以亿计的细胞都需要血液

you would need a pretty powerful pump, right?
身体中就要有一个强大的血液泵来控制

Something that's going to be able to pull in all the blood from the body, and then push it back out.
这个泵要能从身体中把血液抽回来，同时再放出去

And that's what the heart is.
这就是心脏的第一个功能

I mean at its core, that's exactly what the heart is doing.
这就是心脏的核心和本质

扫描二维码进行跟读打分训练

心脏位于胸腔的正中央，从胚胎的第四周开始为人体输送血液，直到死亡为止，从不停止，这个过程大约为人体循环输送1.75亿升血液。本系列课程介绍了人体整个循环系统的组成与各部分的功能，主要内容包括：心脏，血管，血压，淋巴，胎儿与成人的循环过程，血压控制，心肌收缩，心脏的神经调节等内容。

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重点单词		查看全部解释
vessel	['vesl]	想一想再看 n. 容器，器皿，船，舰 n. 脉管，血
flowing	['fləuiŋ]	想一想再看 adj. 流动的；平滑的；上涨的 v. 流动；起源；上涨
constantly	['kɔnstəntli]	想一想再看 adv. 不断地，经常地
core	[kɔ:]	想一想再看 n. 果心，核心，要点 vt. 挖去果核
pump	[pʌmp]	想一想再看 n. 泵，抽水机，打气筒，抽水，打气 v. 打
minutes	['minits]	想一想再看 n. 会议记录，(复数)分钟
smoothly	[smu:ðli]	想一想再看 adv. 平滑地，流畅地
cell	[sel]	想一想再看 n. 细胞，电池，小组，小房间，单人牢房，(蜂房的)巢室