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免疫系统的原理

How does your immune system work? - Emma Bryce

一只蚊子落在你的手臂上
A mosquito lands on your arm,
把化学物质注射入你的皮肤 开始吸血
injects its chemicals into your skin,and begins to feed.
你甚至不知道它在那里
You wouldn ’ t even know it was there,
如果不是红肿块出现
if not for the red lump that appears,
并伴有像是提醒你被咬了的搔痒感
accompanied by a telltale itch.
这是让人讨厌的 但也是
It’s a nuisance, but that bumpis an important signal
你体内免疫系统正在保护你的重要信号
that you’re protectedby your immune system,
免疫系统是你机体防御感染和疾病的主要措施
your body’s major safeguardagainst infection, illness, and disease.
这个系统由一个庞大的细胞、组织和器官网络组成
This system is a vast network of cells,tissues, and organs
它可以协调你机体的防御系统去抵御任何对你健康产生威胁的东西
that coordinate your body’s defensesagainst any threats to your health.
没有它 你就暴露在
Without it, you ’ d be exposed to billions
几十亿的细菌、病毒和毒素之下
of bacteria, viruses, and toxins
这会导致即使很小的病症
that could make something as minor
比如纸片割伤或季节性的感冒都会变得致命
as a paper cut or a seasonal cold fatal.
免疫系统依赖数以百万计的防御性白色血细胞
The immune system relies on millionsof defensive white blood cells,
也被称为白细胞
also known as leukocytes,
它们起源于我们的骨髓
that originate in our bone marrow.
这些细胞流入血液循环和淋巴系统
These cells migrate into the bloodstreamand the lymphatic system,
在血管网络系统中帮助清除体内的毒素和废物
a network of vessels which helpsclear bodily toxins and waste.
我们的体内充满了白细胞
Our bodies are teeming with leukocytes:
在每毫升血液中有4000到11000个
there are between 4,000and 11,000 in every microliter of blood.
当白细胞在移动的时候 它们就像保安人员
As they move around, leukocyteswork like security personnel,
不断的监测血液、组织和器官中的可疑信号
constantly screening the blood,tissues, and organs for suspicious signs.
这个系统主要依赖一种叫抗原的线索
This system mainly relieson cues called antigens.
这些分子会追踪
These molecular traces on the surface
病原体和其它外来物质的表面
of pathogens and other foreign substances
去找到入侵者出现的迹象
betray the presence of invaders.
一旦白细胞探测到入侵者
As soon as the leukocytes detect them,
我们的防御性免疫系统
it takes only minutes
会在几分钟内产生反应并生效
for the body ’ s protective immune response to kick in.
对我们机体产生威胁的东西是多种多样的
Threats to our bodies are hugely variable,
因此免疫反应也必须相应的去适应匹配
so the immune responsehas to be equally adaptable.
那就意味着要依赖很多不同类型的白细胞
That means relying on manydifferent types of leukocytes
用不同的方法去拦截这些威胁
to tackle threats in different ways.
尽管有很多差异 我们仍可以把白细胞分成两种类型
Despite this diversity, we classifyleukocytes in two main cellular groups,
分别协调两种不同分支的攻击手段
which coordinate a two-pronged attack. First,
首先 巨噬细胞触发免疫反应
phagocytes triggerthe immune response
释放巨噬细胞和树突细胞进入血液
by sending macrophagesand dendritic cells into the blood.
在循环过程中 它们通过简单的吞噬
As these circulate, they destroyany foreign cells they encounter,
来消灭任何它们遇到的外来细胞
simply by consuming them.
这可以让巨噬细胞识别
That allows phagocytes to identify the antigen
到它们刚刚吞噬的入侵者身上的抗原
on the invaders they just ingested
并传送这个信息给第二种主要的细胞类型
and transmit this informationto the second major cell group
淋巴细胞来配合进行防御
orchestrating the defense, the lymphocytes.
一种叫做T细胞的淋巴细胞
A group of lymphocyte cells called T-cells go
搜寻感染的体细胞
in search of infected body cells
并快速的消灭它们
and swiftly kill them off. Meanwhile,
同时 B细胞和辅助性T细胞
B-cells and helper T-cells
使用从特定抗原收集来的信息
use the information gatheredfrom the unique antigens
开始制造一种叫做抗体的特殊蛋白
to start producing special proteinscalled antibodies.
这是“主菜”
This is the pièce de résistance:
每一种抗原都有
Each antigen has a unique,
一个特定匹配的抗体能够和它结合
matching antibody that can latch onto it
就像锁和钥匙一样 一起消灭入侵的细胞
like a lock and key, and destroy the invading cells.
B细胞可以产生数百万抗体
B-cells can produce millions of these,
让它们在体内循环和攻击入侵者
which then cycle through the bodyand attack the invaders
直到这些威胁的最有害部分被中和掉
until the worst of thethreat is neutralized.
当这个过程在进行时
While all of this is going on,familiar symptoms,
我们熟悉的症状比如高热和红肿
like high temperatures and swelling,
实际上就是用来辅助免疫反应的过程
are actually processes designedto aid the immune response.
一个发热的身体对于细菌和病毒来说
A warmer body makes it harder
更加困难去复制和传播
for bacteria and viruses to reproduce and spread
因为它们对温度很敏感
because they’re temperature-sensitive.
当机体细胞被损伤时
And when body cells are damaged,
它们释放化学物质导致液体流入周围组织
they release chemicals that make fluid leak into the surrounding tissues,
引起肿胀
causing swelling.
同时也吸引巨噬细胞
That also attracts phagocytes,
来吞噬入侵者和损伤的细胞
which consume the invadersand the damaged cells. Usually,
通常 免疫系统会在数天内根除一个外来威胁
an immune response will eradicate a threat within a few days.
它并不能让你永远不得病
It won ’ t always stop you from getting ill,
尽管它努力去那样做
but that ’ s not its purpose.
它的实际工作是
Its actual job is to stop a threat
去阻止一个外来威胁在你体内上升发展到危险的程度
from escalating to dangerouslevels inside your body.
通过持续的监控
And through constantsurveillance over time,
免疫系统提供另一个福利
the immune systemprovides another benefit:
它帮助我们建立长期免疫
it helps us develop long-term immunity.
当B细胞和T细胞识别抗原时
When B- and T-cells identify antigens,
它们能够使用到这些信息在未来辨认入侵者
they can use that informationto recognize invaders in the future. So,
因此 当威胁再次来临的时候
when a threat revisits,
细胞可以快速地投放正确的抗体
the cells can swiftly deploy the right antibodies
在这个威胁影响到很多细胞之前就拦截掉
to tackle it before it affectsany more cells.
那就是你是如何建立对某种疾病的免疫力的过程 比如水痘
That’s how you can develop immunityto certain diseases, like chickenpox.
但它也不是每一次都有效的
It doesn’t always work so well.
有一些病人有自身免疫性疾病
Some people have autoimmune diseases,
会欺骗免疫系统
which trick the immune system
攻击自己身体里健康的细胞
into attacking the body ’ s own perfectly healthy cells.
没有人知道里面的具体机理
No one knows exactly what causes them,
但这些疾病会不同程度的妨碍免疫系统的工作
but these disorders sabotagethe immune system to varying degrees,
有这种情况的疾病如关节炎
and underlie problems like arthritis,
1型糖尿病和多发性硬化
Type I diabetes, and multiple sclerosis.
然而 对于大多数人来说
For most individuals, however,
一个健全的免疫系统在我们一生中
a healthy immune system will successfully
可以成功击退大约300种感冒
fight off an estimated 300 colds
和无以计数的其他潜在的感染
and innumerable other potential infectionsover the course of a lifetime.
没有它 这些威胁将会上升到高的多的危险程度
Without it, those threats would escalateinto something far more dangerous.
因此下一次
So the next time you catch
你得了感冒或者抓挠蚊子块的时候
a cold or scratch a mosquito bite,
想想免疫系统
think of the immune system.
我们应该感激它保卫我们的生命
We owe it our lives.

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视频概述

免疫系统是如何保卫我们的身体的

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翻译译者

柳叶飞飞刀

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视频来源

https://www.youtube.com/watch?v=PSRJfaAYkW4

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