What happens to your body at the top of Mount Everest - Andrew Lovering

Translator: Cindy So Reviewer: Thomas Tam

If someone teleported from sea level to the top of Mt. Everest,

如果有個人由海平面 瞬間移動到珠穆朗瑪峰山頂

things would go bad fast.

身體情況好快就會轉差

At an altitude of 8,848 meters,

喺海拔 8,848 米

barometric pressure is approximately 33% of what it is at sea level.

氣壓係海平面嘅大概 33%

This means there's significantly less oxygen in the air,

即係空氣中嘅氧氣少咗好多

and our teleported individual would likely suffocate in minutes.

而呢個人好可能會 喺幾分鐘內窒息

However, for people that make this same journey over the course of a month,

但係用一個月時間 行同一段旅程嘅人

it's possible to survive at the peak for hours.

就有可能喺山頂存活幾個鐘

So what can happen to our bodies in just one month

究竟我哋身體喺一個月內 發生咗乜嘢變化

that allows us to endure this incredible altitude?

响不可思議嘅高度 能承受如此低嘅氣壓呢？

Let’s imagine you’re one of the 5.8 billion people

試想像吓 你係 58 億人當中

living less than 500 meters above sea level.

一個生活喺海平面上 唔夠 500 米嘅人

When you take a breath at this altitude,

當你喺呢度吸氣

your lungs fill up with air composed of numerous gases and compounds.

肺部就會充滿含有多種氣體 及化合物組成嘅空氣

Most important among these are oxygen molecules,

其中最重要嘅係氧氣分子

which bind to the hemoglobin in your red blood cells.

佢會同血液入面嘅血紅素結合

Blood then circulates throughout your body,

之後血液喺你嘅全身循環

bringing essential oxygen to all your cells.

為所有細胞帶嚟必需嘅氧氣

But as altitude increases, the air starts to get thinner.

但當海拔升高 空氣就會越稀薄

The relative amounts of each compound remain the same

每種合成嘅氣體相對份量

well into the upper atmosphere,

直至進入高層大氣度都唔會變

but overall, there is less oxygen for our bodies to absorb.

但整體嚟講 身體吸收嘅氧氣會少咗

And if you ascend to altitudes above 2,500 meters,

如果你登上海拔 2,500 米以上

the resulting oxygen deprivation can cause a form of altitude sickness

會引起一種叫做

「急性高山病」嘅高原反應

known as AMS,

often causing headaches, fatigue and nausea.

通常會造成頭痛 疲勞同嘔心

Fortunately, AMS only happens when we ascend too fast,

好彩，急性高山病只會喺 我哋攀登得太快個陣發生

because our bodies have numerous ways of adapting to high altitudes.

因為我哋身體有好多 適應高海拔嘅方法

Within minutes or even seconds of reaching altitudes of 1,500 meters,

喺達到海拔 1,500 米 頭幾分鐘、甚至係頭幾秒

carotid chemoreceptors in your neck sense your blood’s low oxygen pressure.

頸度嘅頸動脈化學感受器 會感知血液嘅低氧壓

This triggers a response that increases the rate and depth of your breathing

從而令到身體作出反應 增加呼吸嘅頻率同深度

to counteract the lack of oxygen.

嚟抗衡缺氧嘅情況

Your heart rate also increases

你嘅心率會提高

and your heart contracts more tightly to pump additional blood with each beat,

心臟亦會更緊密咁收縮 令到每下心跳可以泵出額外嘅血液

quickly moving oxygenated blood around your body.

迅速噉帶含氧嘅血液 喺身體入面流動

All these changes happen relatively fast, and if you were to keep ascending,

呢啲改變發生得相對較快

而如果你要繼續攀登 你嘅心跳率同呼吸就會因而加快

your heart rate and breathing would speed up accordingly.

But if you stayed at this altitude for several weeks,

但係如果你停留喺 呢個高度幾個星期

you could reap the benefits of some longer-term adaptations.

就會由於長期適應咗呢個高度而得益

Within the first few days above 1,500 meters,

喺去到海拔 1,500 米以上嘅頭幾日

the volume of plasma in your blood decreases,

你血液內嘅血漿量會減少

which increases the concentration of hemoglobin.

令到血紅素濃度增加

Over the next two weeks, your hemoglobin levels will continue to rise,

跟住落嚟兩個星期 你嘅血紅素水平會持續上升

allowing your blood to carry even more oxygen per milliliter.

令每毫升嘅血液能帶有更多氧氣

Paired with your high heart rate,

配合埋高心跳率

呢啲高濃度血紅素嘅新血液 有效率噉將氧氣分配到身體各處

this new hemoglobin-rich blood efficiently distributes oxygen throughout your body.

So much so that the volume of blood being pumped with each heartbeat

甚至連每次心跳所泵出嘅血量

can return to normal levels.

都可以回復返正常水平

Over this same time, your breathing also increases even further

喺呢段時間 透過叫做通氣適應過程

in a process called ventilatory acclimatization.

你嘅呼吸亦會進一步增加

After this several weeks of extended acclimatization,

通過咗幾星期延長嘅適應過程

your body has made enough significant changes to climb even higher.

你嘅身體已作出充分嘅改變 令你可以攀得更高

However, you’ll still have to spend additional time acclimating along the way,

但係，你仍然要喺路途上 花額外嘅時間去適應

often climbing back down to recover before ascending even higher.

經常喺登得更高之前 要先行落山俾身體復原

Because the summit of Everest isn't just high,

因為珠穆朗瑪峰唔單止係好高

it’s the highest place on Earth.

佢係地球上最高嘅地方

And at altitudes above 3,500 meters, our bodies are under incredible stress.

喺海拔 3,500 米以上 我哋嘅身體會承受好大壓力

Arteries and veins in the brain dilate to speed up blood flow,

腦入面嘅動脈同靜脈會擴張 以便加速血液流通

But our smallest blood vessels, called capillaries,

但係我哋最細嘅 叫做微絲血管

remain the same size.

啲 size 唔會變

This increased pressure can cause blood vessels to leak,

噉樣增加咗嘅壓力 可能會令到血管滲漏

and fluid to build up in the brain.

喺大腦度積聚液體

A similar issue can occur in the lungs,

類似嘅問題亦可能喺肺部發生

where low oxygen causes blood vessels to constrict,

氧氣不足會令肺部嘅血管收縮

leading to more leaking vessels and fluid buildup.

導致更多血管滲漏同液體積聚

These two conditions— known as HACE and HAPE, respectively—

產生兩種分別叫做 高山腦水腫同高山肺水腫嘅病

are incredibly rare,

雖然非常罕見

but can be life-threatening if not dealt with quickly.

但係如果冇及時處理 就可能會危害生命

Some Tibetans and South Americans with family histories

有啲西藏人同南美人 有居住喺高原嘅家族歷史

of living at high altitude

have genetic advantages that can prevent minor altitude sickness,

佢哋有遺傳嘅基因 嚟預防輕微高山症嘅優勢

but even they aren’t immune to these severe conditions.

就算係噉，都唔能夠 對嚴重高山症免疫

Yet despite these risks, climbers over the last century

即使有呢啲風險 响過去一個世紀

have proved people can go higher than scientists ever thought possible.

登山人士都證明咗 人可以登上比科學家想像中更高嘅地方

Pushing past their body’s limitations,

登山人士可以突破身體極限

these climbers have redefined what humanity can adapt to.

重新定義人類嘅適應能力