【TED演讲】为什么身体在生病时会不舒服？

TED英语演讲课

给心灵放个假吧

演讲题目：The surprising reason you feel awful when you're sick

演讲简介：

开始时你的喉咙有一点痒，接着你开始咳嗽，肌肉变得疼痛，情绪莫名的急躁，变得没有胃口，这些症状表明你得流感了。我们理所当然的认为造成这一系列症状的原因是身体受到了感染，但事实真的是这样吗？Marco A. Sotomayor解释了为什么你的身体会感到不适。

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It starts with a tickle in your throat that becomes a cough.
开始时你的喉咙有一点痒，接着你开始咳嗽。

Your muscles begin to ache, you grow irritable, and you lose your appetite.
你的肌肉开始疼痛，你变得易怒，变得没有胃口。

It's official: you've got the flu.
这些症状表明你得流感了。

It's logical to assume that this miserable medley of symptoms is the result of the infection coursing through your body, but is that really the case?
我们理所当然的认为造成这一系列症状的原因是身体受到了感染，但事实真的是这样吗？

What's actually making you feel sick?
到底是什么让我们感到身体不适？

What if your body itself was driving this vicious onslaught?
如果是我们的身体在攻击它自己呢？

You first get ill when a pathogen like the flu virus gets into your system, infecting and killing your cells.
当流感病毒这样的病原体进入体内感染并杀死细胞时，你才会感到生病。

But this unwelcome intrusion has another effect: it alerts your body's immune system to your plight.
但这种并不受欢迎的侵入却有另一种作用，它会使你身体的免疫系统注意于当下的状况。

As soon as it becomes aware of infection, your body leaps to your defense.
只要发生感染，免疫系统便立刻作出反应。

Cells called macrophages charge in as the first line of attack, searching for and destroying the viruses and infected cells.
巨噬细胞作为第一线的攻击者，将会搜索并消灭病毒与受感染的细胞。

Afterwards, the macrophages release protein molecules called cytokines whose job is to recruit and organize more virus-busting cells from your immune system.
然后巨噬细胞会释放一种叫作细胞因子的蛋白质分子，它会从免疫系统中征集并组织更多的细胞来杀死病毒。

If this coordinated effort is strong enough, it'll wipe out the infection before you even notice it.
如果这一阶段的协调作用足够强的话，它会在你丝毫不知情的状态下清除感染。

But that's just your body setting the scene for some real action.
但这只是你身体为一些实际行动所作出的准备。

In some cases, viruses spread further, even into the blood and vital organs.
在某些情况下，病毒会进一步传播，甚至进入血液和重要器官。

To avoid this sometimes dangerous fate, your immune system must launch a stronger attack, coordinating its activity with the brain.
为了避免这种可能发生的危险，你的免疫系统必须发起更强的进攻，协调与大脑的活动。

That's where those unpleasant symptoms come in, starting with the surging temperature, aches and pains, and sleepiness.
这就是那些引起不适的症状来源，体温开始升高，身体疼痛和昏昏欲睡。

So why do we experience this?
那么，我们为什么会经历这种情况呢？

When the immune system is under serious attack, it secretes more cytokines, which trigger two responses.
当免疫系统受到严重攻击时，它会分泌更多的细胞因子，从而引发两种反应。

First, the vagus nerve, which runs through the body into the brain, quickly transmits the information to the brain stem,
首先，迷走神经穿过身体进入大脑，迅速将信息传递到脑干，

passing near an important area of pain processing.
一个控制疼痛过程的重要区域。

Second, cytokines travel through the body to the hypothalamus, the part of the brain responsible for controlling temperature, thirst, hunger,
其次，细胞因子通过身体传递到下丘脑，这是大脑中负责控制温度、口渴、饥饿、

and sleep, among other things.
睡眠，还有其他一些事情的部分。

When it receives this message, the hypothalamus produces another molecule called prostaglandin E2, which gears it up for war.
当下丘脑收到这一信息时，它会产生另一种名为前列腺素E2的分子，为战争做好准备。

The hypothalamus sends signals that instruct your muscles to contract and causes a rise in body temperature.
下丘脑发出信号，指示肌肉收缩，导致体温上升。

It also makes you sleepy, and you lose your appetite and thirst.
它还会让你昏昏欲睡，感受不到饥饿和口渴。

But what's the point of all of these unpleasant symptoms?
但所有这些令人不快的症状有什么意义呢？

Well, we're not yet sure, but some theorize that they aid in recovery.
我们目前还不清楚，但是有些理论认为这有助于恢复。

The rise in temperature can slow bacteria and help your immune system destroy pathogens.
温度的升高可以减缓细菌的传播速度，并帮助你的免疫系统消灭病原体。

Sleep lets your body channel more energy towards fighting infection.
睡眠可以让你的身体输送更多的能量来对抗感染。

When you stop eating, your liver can take up much of the iron in your blood, and since iron is essential for bacterial survival,
当你停止进食，你的肝脏可以吸收血液中大量的细菌赖以生存的铁，

that effectively starves them.
有效的消灭细菌。

Your reduced thirst makes you mildly dehydrated, diminishing transmission through sneezes, coughs, vomit, or diarrhea.
感觉不到口渴会使你轻微脱水，减少通过打喷嚏，咳嗽，呕吐，和腹泻传播的病菌。

Though it's worth noting that if you don't drink enough water, that dehydration can become dangerous.
但值得注意的是，如果你没有喝足够的水，脱水可能会变得危险。

Even the body's aches make you more sensitive, drawing attention to infected cuts that might be worsening, or even causing your condition.
你会对身体的疼痛更加敏感，特别要注意受感染的伤口可能会恶化甚至影响你的整体状态。

In addition to physical symptoms, sickness can also make you irritable, sad, and confused.
除了身体上表现出的症状，疾病也会让你感到烦躁，伤心，和困惑。

That's because cytokines and prostaglandin can reach even higher structures in your brain, disrupting the activity of neurotransmitters,
这是因为细胞因子和前列腺素可以到达你大脑中更高的结构，破坏神经递质活性，

like glutamate, endorphins, serotonin, and dopamine.
比如谷氨酸、内啡肽、血清素，和多巴胺。

This affects areas like the limbic system, which oversees emotions, and your cerebral cortex, which is involved in reasoning.
这种行为会影响控制情绪的大脑边缘系统和进行推理的大脑皮层。

So it's actually the body's own immune response that causes much of the discomfort you feel every time you get ill.
因此，实际上是身体自身的免疫反应导致你每次生病时的不适反应。

Unfortunately, it doesn't always work perfectly.
可惜，免疫系统并不是总能完美运行。

Most notably, millions of people worldwide suffer from autoimmune diseases, in which the immune system treats normal bodily cues as threats,
最值得注意的是，全球数以百万计的人患有自身免疫性疾病，因为他们的免疫系统将正常的身体信号视为威胁，

so the body attacks itself.
所以对自身进行攻击。

But for the majority of the human race, millions of years of evolution have fine-tuned the immune system so that it works for,
但是对于大多数人，免疫系统历经数百万年的进化，

rather than against us.
不会对自身产生排斥反应。

The symptoms of our illnesses are annoying, but collectively,
我们自身疾病所引发的症状令人不适，但总体来说，

they signify an ancient process that will continue barricading our bodies against the outside world for centuries to come.
他们是一种古老的过程，并将在未来的世纪中继续保护我们的身体不受外界影响。

视频、演讲稿均来源于TED官网

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