凍死時會發生什麼事？：英語精讀講義

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

人類不像許多祖先那樣長有皮毛，

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

但我們的身體仍然具備適應寒冷天氣的能力。

However, when pushed, 慣用語

然而，一旦被逼到極限，

these mechanisms can fail leading to an extreme breakdown. 文法

這些機制就可能失效，導致身體機能嚴重崩潰。

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

那麼，當你被凍死時，你的身體和大腦

when you freeze to death? 片語搭配

究竟會發生什麼變化？

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

當核心體溫降到攝氏37度以下時，就會出現失溫症。

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

所以，當身體暴露在極寒環境中時，

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

幾分鐘內，皮膚就會向下視丘發出訊號，

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

引發所謂的體溫調節效應器反應。

First, the blood vessels in our skin narrow,

首先，皮膚中的血管會變窄，

allowing the body to maintain its core temperature

讓身體得以維持核心體溫，

by reducing the blood flow on its surface,

方法是減少流向體表的血液，

known as vasoconstriction.

這個過程稱為血管收縮。

Additionally, brown adipose tissue located throughout the body also activates

此外，遍布全身的棕色脂肪組織也會被活化，

using high levels of glucose and lipids

消耗大量葡萄糖和脂質，

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

透過稱為「非顫抖性產熱」的過程產生熱量。

But if all else fails, 慣用語

但如果這些方法全都失效，

our body undergoes shivering thermogenesis

身體就會啟動顫抖性產熱，

as a last-ditch effort. 慣用語

作為最後一搏。

By constantly contracting our skeletal muscles, 文法

藉由持續收縮骨骼肌，

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

身體會引發顫抖，試圖產生足夠熱量來預防失溫症。

However, if you remain exposed to the cold

然而，如果你持續暴露在寒冷環境中，

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

30分鐘內就可能凍傷，

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

也就是皮膚和其他組織真的開始凍結。

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

形成的冰晶會破壞細胞膜，危及細胞，

causing intracellular dehydration due to water leaking out from them.

水分會從細胞中滲出，導致細胞內脫水。

The cells then begin to die

接著，細胞開始死亡，

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

冰晶則不斷擴大，損害鄰近細胞。

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

為了因應，身體會透過血管擴張來防止皮膚凍傷，

which allows increased blood flow to warm the skin cells.

藉此增加血流量，讓皮膚細胞暖起來。

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

然而，這和體溫調節效應器反應背道而馳，

which again works to maintain our core temperature through vasoconstriction.

因為後者仍會透過血管收縮來維持核心體溫。

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

結果，身體會在血管擴張與收縮之間反覆循環，

thawing and freezing our skin over and over again,

讓皮膚一再解凍又凍結，

and causing even more damage.

造成更嚴重的傷害。

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

但在極端低溫下，會凍結的不只有皮膚。

If you're in extreme cold, windy weather,

如果你身處極寒又颳著強風的天氣中，

your corneas can freeze, too.

角膜也可能凍結。

The protective layer of tears covering the cornea can dry,

覆蓋角膜、具有保護作用的淚膜可能會乾掉，

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

使眼睛變得畏光，並造成眼瞼痙攣。

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

幸好，只要迅速離開寒冷環境，角膜就能解凍，

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

但如果凍結太久，便可能造成永久性損傷。

Now, several factors, including body composition,

這時，有幾項因素，包括身體組成、

clothing, temperature, and the environment,

衣著、溫度和周遭環境，

determine how quickly your core body temperature drops. 文法

會決定核心體溫下降的速度。

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

例如，身體在水中流失熱量的速度遠比在空氣中快。

Those who were submerged in the icy waters

那些浸泡在冰冷海水中的人，

after the sinking of the Titanic

在鐵達尼號沉沒後，

may have lasted only 15 minutes. 文法

可能只撐了15分鐘。

This is because during the advanced stage of hypothermia,

這是因為，失溫症進入晚期階段時，

your organs begin to fail.

你的器官會開始衰竭。

Your breathing rate slows, you lose coordination,

呼吸速度會變慢，協調能力也會喪失，

your heart rate begins to slow down,

心跳開始減緩，

and your body even stops shivering.

身體甚至會停止顫抖。

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

晚期失溫症最後出現的症狀之一是譫妄。

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

一項針對失溫致死案例的調查

found that in 25% of the cases,

發現，在25%的案例中，

the victims had undressed before they died. 文法

死者在臨死前脫掉了衣服。

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

其中一個案例裡，死者把衣服整齊摺好，放在身旁，

and froze to death in the snow.

最後在雪地裡凍死。

Why would this happen?

為什麼會這樣？

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

一種理論認為，極寒造成的腦部損傷

causes people to think that they're burning up, 慣用語

會讓人覺得自己熱得發燙，

so they strip naked and cool down. 片語搭配

於是脫光衣服來降溫。

Another theory suggests that the muscles that cause cutaneous vasoconstriction

另一種理論認為，負責引發皮膚血管收縮的肌肉

in our blood vessels get exhausted

也就是血管中的肌肉，會變得疲憊不堪，

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

使身體核心部位的血液一下子湧向體表，

resulting in a hot flash.

引發一陣潮熱。

This is all pretty bleak, 用詞

這一切都讓人相當絕望，

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

但如果你發現有人看起來已經凍死，

you may want to warm them up. 語氣意圖

或許可以試著讓對方恢復體溫。

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

一篇標題十分貼切的論文《只有復溫後仍死亡，才算真正死亡》，

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

記錄了一名因溺水而失溫、已無生命跡象的病患。

This patient was successfully resuscitated

這名病患最後成功獲救，

with a 3-hour bypass surgery

醫師進行了長達3小時的體外循環手術，

used to warm his body. 文法

藉此讓他的身體復溫。

Though parts of his body required amputation, 文法

雖然他身體的一些部位不得不截除，

in 11 weeks he successfully recovered

但僅用11週，他便順利康復，

with normal neurological function.

神經功能也恢復正常。

Just remember, when the temperature starts to drop,

請記住，當氣溫開始下降時，

do everything you can to stay warm 片語搭配

務必想盡辦法讓自己保持溫暖，

because your body can only do so much 慣用語

因為身體能做的畢竟有限，

to fight the extreme cold.

無法一直抵禦極寒。

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

那麼，有哪些技巧能幫助你避免凍死？

We made a video of step-by-step strategies

我們製作了一支影片，逐步介紹各種求生策略，

to stay alive if you're ever trapped

幫助你在不慎受困

in the extreme cold.

於極寒環境時活下來。

Click here to learn the life-saving,

點這裡，了解這些能救命、

but also gruesome things you need to know

卻也令人毛骨悚然的必備知識，

to avoid hypothermia and freezing to death.

從而避免失溫症與凍死。

With climate change causing extreme weather, 文法

隨著氣候變遷引發極端天氣，

we may all need this info in the future.

未來我們可能都會需要這些資訊。

And subscribe for more weekly science videos.

記得訂閱頻道，每週收看更多科學影片。