未登录,请登录后再发表信息
最新评论 (0)
播放视频

免疫系统

Immune System

《阿米巴姐妹》
An overview of all of the major body systems is nice,
将人体各大系统作为整体来观察固然不错
but something remarkable happens
但当深入探究某个系统时
when you explore one body system at a time in a bit more depth.
你就会发现一些不同寻常的事情
And—in our opinion, one of the most fascinating systems of all is the immune system.
例如在我们看来 免疫系统是最奇妙的系统之一
Why?
这是为什么呢?
Because it features cells in your body that work—day and night—
因为免疫系统的细胞日夜不停工作
together to protect you from a constant threat of pathogens trying to bring mayhem.
协力保护你免受病原体持续威胁所带来的伤害
And most of the time, you don’t even know it.
而大部分时候 你甚至察觉不到它们的活动
Most of the time.
大部分时候
By pathogen, I could mean a lot of things.
病原体有很多种
A line-up: Viruses. Bacteria. Fungi. Protists. Parasitic worms.
比如:病毒 细菌 真菌 原生生物 寄生虫
We could go on…
除此以外还有很多种……
Your body has external protection against these things. Like your skin.
人体有外围防护线 比如皮肤 来抵御病原体
We call that a first line of defense
我们称之为第一道防线
because it’s the first line against letting these pathogens inside your body.
因为这是防止病原体进入体内的第一道屏障
Mucous membranes too,
粘膜也属于此类
like the lining of your nose will keep pathogens from getting inside.
比如你的鼻黏膜会阻止病原体侵入
This first line of defense is nonspecific,
第一道防线属于非特异性免疫
because it’s not selective about what it blocks from getting into your body.
因为它不会有选择性地阻止哪些东西入侵
But this is all not full proof and sometimes they do get in.
但这并不万无一失 有时病原体还是会入侵体内
And when they do, your immune system has all kinds of ways to deal.
当它们入侵时 你的免疫系统就会采用各种方法来应对
After all, this is not its first rodeo.
毕竟 这也不是第一次了
So let’s say they break through our first line of defense.
所以 我们假设它们突破了第一道防线
Well, the 2nd line of defense, includes the inflammatory response.
第二道防线包括炎症反应
To explain it very simply—
简单地解释一下——
let’s say you step on a sharp stick.
假设你踩到了一个尖尖的棍子
And there’s some bacteria on that stick
并且棍子上有一些细菌
in your foot.
会进到你脚中
The initial damage of this stick into your foot
这根棍子最初对你的脚造成的破坏
can cause certain types of cells, such as a mast cell, to react.
会导致某类细胞的反应 比如肥大细胞
These cells are filled with substances that
这些细胞体内充满了多种
work with allergic responses and inflammatory responses too.
与过敏反应和炎症反应有关的物质
One substance that they contain is histamine.
它们含有的其中一种物质叫做组胺
If they are triggered to release histamine,
如果它们释放了组胺
the result is that this will cause blood vessels to dilate —
就会导致伤口附近的血管扩张——
meaning they widen—near the injury.
这意味着血管会变宽
Histamine also contributes to making these blood vessels leakier.
组胺也会使这些血管发生渗漏
The dilation and the leakiness of the blood vessel
血管的扩张与渗漏
makes it easier for many types of white blood cells
使得各种白细胞更容易到达这些区域
such as certain types of macrophages to reach the area.
比如 某些类型的巨噬细胞
And macrophages do what macrophages do best.
而巨噬细胞会做自己最擅长的工作
They consume the pathogens.
它们将这些病原体吞噬掉
Additionally, your body has a complement system.
另外 你的体内还有补体系统
The complement system is not what it sounds like.
这个补体系统并不是它听起来的那样
It basically works to help or complement the actions of the immune system.
它的主要工作是帮助或配合免疫系统的行动
It can work with non-specific or specific responses.
它可以作用于非特异性和特异性反应
In this situation, the release of complement factors
在这种情况下 它会释放补体因子
in this case can further attract macrophages to the area to consume pathogens.
来进一步引导巨噬细胞到达该区域并吞噬病原体
When all of this signaling stops,
当这些信号都消失时
the damaged area can return to normal.
受伤的区域就可以恢复正常
The pathogen has been terminated.
病原体已经被消灭了
However, that also was a nonspecific response.
然而 这也是非特异性反应
Who knows what was on that stick?
谁知道那个棍子上有什么?
So that takes us to the 3rd line of defense.
这就要说到第三道防线了
The specific line of defense.
即 特异性免疫
If you had a cold virus spreading throughout your body,
如果感冒病毒在你的全身蔓延
you may need your response to be targeted on that pathogen.
你可能需要针对这种病原体的免疫反应
Now, it`s we give our typical notice,
现在 如往常一样 我们要提醒一下
the immune system is very complex.
免疫系统非常复杂
We’ve just been giving some basics,
我们刚刚说的只是基础知识
and we’re going to continue to do so,
接下来要讲的也很基础
but there are a lot of extra details and exceptions
但是 还有许多细节和例外的信息
that this short video can’t go into.
在这个短视频中难以深入展开
We encourage you to explore.
我们鼓励你去探索
Ok so we mentioned, what if we need a more targeted response?
我们讲到了 如果我们需要一个更有针对性的反应呢?
We’re moving into something known as adaptive immunity.
我们要讲到适应性免疫
Sounds fancy, this is a specific response to an antigen.
听起来很奇妙 它是对抗原的特异性反应
An antigen is something the body recognizes as non-self,
抗原是人体识别为非自身的物质
and in this case, it is something that would be a part of the pathogen.
这种情况下 它可能是病原体的一部分
This adaptive response is going to be the third line of defense
当第一 第二道防线不足以消灭病原体时
as the first and second line of defense may have not been enough to control the pathogen.
这种适应性反应将作为第三道防线起作用
We’re going to focus on the basics of two adaptive responses:
我们将重点介绍两种适应性反应的基础知识:
cell-mediated and humoral.
细胞免疫和体液免疫
Cell-mediated.
细胞免疫
This involves the cytotoxic T cell.
这一过程需要细胞毒性T细胞
The cytotoxic T cell is a white blood cell
细胞毒性T细胞是一种
that has the ability to destroy cells that have been infected by the pathogen.
能破坏已感染病原体细胞的白细胞
It does this by releasing signals that causes the infected cell to do apoptosis,
它通过释放信号分子 使被感染细胞凋亡
which is a type of self destruct.
凋亡是细胞自我毁灭的一种
It can do this by releasing a protein called perforin
它是通过释放一种叫穿孔蛋白的蛋白质来实现的
which actually causes holes in the cell membrane.
穿孔蛋白确实会让细胞膜穿孔
This causes water and ions to flow into it and destroys the cell.
这使得水和离子流入细胞内部并破坏细胞
When cells that have been infected by a pathogen are destroyed,
当感染病原体的细胞被破坏了
this can also destroy the pathogen
病原体自身也会被破坏
or it can mean the pathogen
或者说 至少病原体
at least can no longer replicate inside that infected cell.
不能再在被感染的细胞内繁殖了
The thing is, for this response to work,
问题是 只有激活了细胞毒性T细胞
you have to stimulate a cytotoxic T cell.
才能发生这种反应
Stimulating a cytotoxic T cell could mean
激活细胞毒性T细胞需要
an infected cell presents an antigen from the pathogen that has infected it.
受感染的细胞呈递病原体的抗原
The infected cell presents the antigen on its own cell membrane.
被感染的细胞把抗原呈递在自己的细胞膜上
Kind of like a little flag saying, hey, I’ve been infected
这有点像一面小旗 上面写着 嘿 我被感染了
and here you go, this is what it is.
快来 就是它
This activates cytotoxic T cells to bind
这就激活了细胞毒性T细胞
and release signals that causes the infected cell to perform apoptosis.
并与被感染的细胞结合 释放让它凋亡的信号
But there’s another way to stimulate cytotoxic-T cells too.
但还有另一种途径可以激活细胞毒性T细胞
Remember how macrophages may have been consuming the pathogen?
还记得巨噬细胞是如何吞噬病原体的吗?
When they do, they process the pathogen,
它们吞噬的同时还会处理病原体
and the antigens from the pathogen are transferred to the macrophage’s surface.
将病原体的抗原转移到巨噬细胞的表面
A white blood cell called the T-helper cell can bind.
一种叫做T辅助细胞的白细胞可以与之结合
The macrophage will release chemical signals,
巨噬细胞将会释放化学信号
which then causes the T-helper cell to release chemical signals
并使辅助T细胞释放化学信号
which then can stimulate cytotoxic T cells.
这就会刺激细胞毒性T细胞
Cytotoxic T cells will be in search of infected cells
细胞毒性T细胞将会寻找被感染细胞
so they can stop the pathogen,
从而阻止病原体
and they will also continue to amplify the immune response.
之后 它们将继续强化免疫反应
That’s the cell-mediated response, simplified.
这就是简化版的细胞免疫反应
But remember how we mentioned those helper T cells?
但是 还记得我们怎么提到辅助T细胞的吗?
They’re big helpers as they help not only in the cell-mediated response,
它们帮了很大忙 因为它们不仅辅助细胞免疫
but they also help in the humoral response.
它们还协助体液免疫
So what happens in the humoral response?
那么 体液反应是怎么回事呢?
In one scenario, a macrophage has consumed a pathogen
一种情况是 巨噬细胞吞噬了病原体
and once again, has an antigen from the pathogen on its cell membrane surface.
同样地把抗原从病原体呈递到细胞膜表面
Then, it binds a Helper T Cell.
然后 它与辅助T细胞结合
That Helper T Cell could also stimulate
辅助T细胞也可以激发
a white blood cell known as a B cell.
一种叫做B细胞的白细胞
B cells are white blood cells that have the ability
B细胞是一种白细胞
to make something called antibodies.
并且可以产生一种叫抗体的物质
Before I define antibody,
在解释抗体之前
can we just take a moment and recognize there are three words
先花点时间分辨三个听起来非常相似
that sound very similar and can involve the immune system.
且与免疫系统相关的词
Antigen which is something that the immune system recognizes as foreign to the body.
抗原是被免疫系统识别为外来异物的东西
We’ve been mentioning that one a lot.
这个我们已经提过很多次了
Antibiotics are substances that can specifically destroy bacteria;
抗生素是一种专门杀灭细菌的物质
we have a separate video on those.
我们有另外的视频单独介绍
But antibodies are something totally different.
但是抗体是完全不同的
Antibodies are proteins, and they tend to be in a “Y” shape.
抗体是蛋白质 它们往往呈“Y”形
Antibodies have an antigen binding area where they bind a specific antigen.
抗体有一个可以与特定的抗原结合的区域
They will be found in blood
抗体存在于血液中
but many antibodies can also be found
但很多抗体也存在于
in mucus, saliva, breast milk, and more.
粘液 唾液和乳汁等体液中
There are different classes of antibodies.
抗体有许多种
For example, IgE can protect against parasitic worms.
例如 免疫球蛋白E可以阻止寄生虫入侵
And it’s responsible for a lot of allergic reactions.
同时它也会引起很多过敏反应
Antibodies are generally very specific
抗体通常具有很强的特异性
so there must be an antibody that is able to bind to an antigen.
所以一定有一种抗体能与一种抗原结合
When antibodies bind an antigen,
当抗体与抗原结合时
they can deactivate the pathogen by affecting the ability of
它们可以通过影响病原体的移动和繁殖能力
the pathogen to move, reproduce, or cause harm.
或对病原体造成伤害 以此灭活它们
The binding can also be like signs telling macrophages,
这种结合也可以作为通知巨噬细胞的信号
“Here it is. Come eat it!”
“它在这里 过来吃呀!”
So activating B cells causes these antibodies to be produced,
所以激活B细胞能产生这些抗体
and this is part of the humoral response.
同时 这也是体液反应的一部分
While B cells can be activated by a T helper cell,
B细胞不仅可以被T辅助细胞激活
they can also be activated by free antigens themselves that they may come in contact with.
还可能被碰巧接触到的游离的抗原本身激活
Now, we do want to mention
现在 我们要提到
that both in the humoral and cell-mediated response,
在体液免疫和细胞免疫中
there are memory cells.
都有记忆细胞
There are Memory B cells and Memory T cells.
包括记忆B细胞和记忆T细胞
These cells keep a “memory” of the antigen that they were exposed to.
这些细胞对它们接触过的抗原保有“记忆”
Memory B cells can activate Plasma B cells which will make antibodies.
记忆B细胞可以激活能产生抗体的血浆B细胞
Memory T cells can activate cytotoxic T cells
记忆T细胞可以激活细胞毒性T细胞
which will go after infected cells.
它们会追捕被感染的细胞
The ability to keep a memory is very important,
这种保存记忆的能力非常重要
and this is also where vaccines come in.
这也是疫苗能够被发明的原因
Vaccines can introduce either an inactivated or very weakened pathogen.
疫苗可以引入灭活的或非常弱的病原体
This means the body does not get the disease itself,
这意味着被接种的人不会患上这种疾病
but it will launch an immune response.
但它会引起一种免疫反应
By launching an immune response,
通过启动免疫反应
there will ultimately be memory immune cells
最后会产生记忆免疫细胞
that will be involved in launching an efficient attack
如果将来遇到相应的病原体
if that pathogen is ever encountered in the future.
它们会参与发动一场高效的攻击
Overall, this immune system that you have, it’s pretty incredible.
总之 你拥有的免疫系统是非常不可思议的
There are entire giant textbooks about this topic alone
仅关于免疫系统 就有很多大部头的教科书
and careers dedicated to studying it.
也有许多职业 致力于研究免疫系统
Well, that’s it for the Amoeba Sisters,
这就是今天《阿米巴姐妹》的全部内容
and we remind you to stay curious.
我们希望你能常怀好奇
[Music]
[音乐声]
想看这些或更多精彩内容 请登录www.amoebasisters.com!

发表评论

译制信息
视频概述

人体究竟是如何抵御外敌入侵的?快来了解人体免疫系统的三道防线吧。

听录译者

收集自网络

翻译译者

Viviean📖

审核员

审核员LJ

视频来源

https://www.youtube.com/watch?v=fSEFXl2XQpc

相关推荐