冻死时会发生什么？：英语精读讲义

Humans don't have fur like many of our ancestors,

人类不像许多祖先那样长有皮毛，

but our bodies still have the ability to adapt to cold weather. 短語搭配

但我们的身体仍然具备适应寒冷天气的能力。

However, when pushed, 習語

然而，一旦被逼到极限，

these mechanisms can fail leading to an extreme breakdown. 語法

这些机制就可能失效，导致身体机能严重崩溃。

So, what actually happens to your body and brain 表達脈絡

那么，当你被冻死时，你的身体和大脑

when you freeze to death? 短語搭配

究竟会发生什么变化？

Hypothermia occurs when the core body temperature drops below 37 degrees Celsius. 用詞

当核心体温降到37摄氏度以下时，就会出现低体温症。

So, in the event that the body is exposed to extreme cold, 講解

所以，当身体暴露在极寒环境中时，

within minutes signals are sent from the skin to the hypothalamus,

几分钟内，皮肤就会向下丘脑发送信号，

producing what is known as the thermoeffector response. 短語搭配

引发所谓的体温调节效应器反应。

First, the blood vessels in our skin narrow,

首先，皮肤中的血管会变窄，

allowing the body to maintain its core temperature

让身体能够维持核心体温，

by reducing the blood flow on its surface,

方法是减少流向体表的血液，

known as vasoconstriction.

这一过程称为血管收缩。

Additionally, brown adipose tissue located throughout the body also activates

此外，遍布全身的棕色脂肪组织也会被激活，

using high levels of glucose and lipids

消耗大量葡萄糖和脂质，

to produce heat via a process called non-shivering thermogenesis. 短語搭配

通过一种叫作“非颤抖产热”的过程产生热量。

But if all else fails, 習語

但如果这些办法全都不起作用，

our body undergoes shivering thermogenesis

身体就会启动颤抖产热，

as a last-ditch effort. 習語

作为最后一搏。

By constantly contracting our skeletal muscles, 語法

通过持续收缩骨骼肌，

our body induces shivering in an attempt to produce enough heat to prevent hypothermia. 短語搭配

身体会引发颤抖，试图产生足够的热量来预防低体温症。

However, if you remain exposed to the cold

然而，如果你继续暴露在寒冷环境中，

within 30 minutes, you could get frostbite, 短語搭配

30分钟内就可能出现冻伤，

which is when your skin and other tissues literally begin to freeze. 語法

也就是皮肤和其他组织真的开始冻结。

Developing ice crystals endanger your cells by damaging their cell membranes,

形成的冰晶会破坏细胞膜，危及细胞，

causing intracellular dehydration due to water leaking out from them.

导致水分从细胞中渗出，造成细胞内脱水。

The cells then begin to die

随后，细胞开始死亡，

and the ice crystals continue to expand, damaging neighboring cells.

冰晶则继续扩张，破坏周围的细胞。

In response, the body tries to prevent frostbite in our skin through vasodilation,

作为应对，身体会通过血管扩张来防止皮肤冻伤，

which allows increased blood flow to warm the skin cells.

从而增加血流量，让皮肤细胞暖起来。

However, this runs counter to the thermoeffector response, 短語搭配

然而，这与体温调节效应器反应背道而驰，

which again works to maintain our core temperature through vasoconstriction.

因为后者仍会通过血管收缩来维持核心体温。

As a result, our body goes through cycles of vasodilation and vasoconstriction, 講解

结果，身体会在血管扩张和血管收缩之间反复切换，

thawing and freezing our skin over and over again,

使皮肤一次又一次地解冻、再冻结，

and causing even more damage.

造成更严重的损伤。

But our skin isn't the only spot that will freeze under extreme cold temperatures. 語法

但在极端低温下，会冻结的并不只有皮肤。

If you're in extreme cold, windy weather,

如果你身处极寒且大风的天气中，

your corneas can freeze, too.

角膜也可能冻结。

The protective layer of tears covering the cornea can dry,

覆盖角膜、起保护作用的泪膜可能会变干，

making your eyes sensitive to light and causing eyelid spasms. 語法

让眼睛对光线变得敏感，并引发眼睑痉挛。

Luckily, your corneas can thaw if you get yourself out of the cold quickly, 短語動詞

幸运的是，如果你迅速离开寒冷环境，角膜可以解冻，

but if frozen long enough, you can cause permanent damage. 語法

但如果冻结太久，就可能造成永久性损伤。

Now, several factors, including body composition,

这时，有几个因素，包括身体组成、

clothing, temperature, and the environment,

衣着、温度和周围环境，

determine how quickly your core body temperature drops. 語法

会决定核心体温下降的速度。

For example, heat is lost much more quickly in water than in air. 語法

例如，热量在水中流失的速度远快于在空气中。

Those who were submerged in the icy waters

那些浸没在冰冷海水中的人，

after the sinking of the Titanic

在泰坦尼克号沉没后，

may have lasted only 15 minutes. 語法

可能只坚持了15分钟。

This is because during the advanced stage of hypothermia,

这是因为，当低体温症进入晚期阶段时，

your organs begin to fail.

你的器官会开始衰竭。

Your breathing rate slows, you lose coordination,

你的呼吸会变慢，协调能力也会丧失，

your heart rate begins to slow down,

心率开始下降，

and your body even stops shivering.

身体甚至会停止颤抖。

One of the last symptoms of advanced stage hypothermia is delirium. 語法

晚期低体温症最后出现的症状之一是谵妄。

A survey of cases in which death was caused by hypothermia 表達脈絡

一项针对低体温症致死案例的调查

found that in 25% of the cases,

发现，在25%的案例中，

the victims had undressed before they died. 語法

死者在临死前脱掉了衣服。

In one case, victims had neatly folded their clothes beside them

在其中一个案例中，死者把衣服整齐地叠好，放在身旁，

and froze to death in the snow.

随后在雪地里被冻死。

Why would this happen?

为什么会这样？

One theory is that the brain damage that results from the extreme cold 講解

一种理论认为，极寒导致的脑损伤

causes people to think that they're burning up, 習語

会让人觉得自己热得发烫，

so they strip naked and cool down. 短語搭配

于是脱光衣服来降温。

Another theory suggests that the muscles that cause cutaneous vasoconstriction

另一种理论认为，负责引发皮肤血管收缩的肌肉

in our blood vessels get exhausted

也就是血管中的肌肉，会变得疲惫不堪，

and cause blood from our core to rush to the surface of our body, 短語搭配

使身体核心部位的血液一下子涌向体表，

resulting in a hot flash.

引发一阵潮热。

This is all pretty bleak, 用詞

这一切都让人相当绝望，

but if you find someone who appears to be frozen to death,

但如果你发现有人看上去已经被冻死，

you may want to warm them up. 語氣意圖

你或许应该试着为对方复温。

An aptly named paper, "No One Is Dead Until Warm and Dead," 講解

一篇标题十分贴切的论文《只有复温后仍死亡，才算真正死亡》，

chronicles a patient with hypothermia caused by drowning with no signs of life. 短語搭配

记录了一名因溺水而患上低体温症、已无生命迹象的患者。

This patient was successfully resuscitated

这名患者最终被成功救活，

with a 3-hour bypass surgery

医生进行了长达3小时的体外循环手术，

used to warm his body. 語法

用这种方式让他的身体复温。

Though parts of his body required amputation, 語法

尽管他身体的一些部位不得不被截除，

in 11 weeks he successfully recovered

但仅用11周，他便顺利康复，

with normal neurological function.

神经功能也恢复正常。

Just remember, when the temperature starts to drop,

请记住，当气温开始下降时，

do everything you can to stay warm 短語搭配

一定要想尽办法让自己保持温暖，

because your body can only do so much 習語

因为你的身体所能做的终究有限，

to fight the extreme cold.

无法一直抵御极寒。

So, what are the techniques to help your body survive freezing to death?

那么，有哪些技巧能帮助你避免被冻死？

We made a video of step-by-step strategies

我们制作了一段视频，逐步讲解各种求生策略，

to stay alive if you're ever trapped

帮助你在不慎被困

in the extreme cold.

于极寒环境时活下来。

Click here to learn the life-saving,

点击这里，了解这些能救命、

but also gruesome things you need to know

却也令人毛骨悚然的必备知识，

to avoid hypothermia and freezing to death.

从而避免低体温症和被冻死。

With climate change causing extreme weather, 語法

随着气候变化引发极端天气，

we may all need this info in the future.

未来我们可能都会用到这些信息。

And subscribe for more weekly science videos.

还请订阅频道，每周观看更多科学视频。