It's a process you rarely think about,

這是一個你很少去想到的過程

but behind the scenes, a huge coordinated effort is playing out.

但在這背後正有著巨大的協調力量運作著

Your vital organs,

你的重要器官

the gut,

內臟

brain,

大腦

bones,

骨頭

lungs,

肺

blood,

血液

and heart

和心臟

work together to sustain your life

一起運作著以維持你的生命

by delivering oxygen to tissues throughout your body.

藉由運送氧氣到身體的各個組織

Most of our cells need oxygen

我們大部分的細胞都需要氧氣

because it's one of the key ingredients of aerobic respiration.

因為這是呼吸作用其中一個重要的原料

That's the process that produces a molecule called ATP,

這個過程製造一種分子稱做ATP（三磷酸腺苷）

which our cells use to power their many incredible functions.

使我們的細胞有更好的作用和功能

But getting oxygen throughout our bodies is a surprisingly difficult task.

但將氧氣輸送到全身卻是意外困難的任務

Gas enters cells by diffusing in from their surroundings.

氣體藉由擴散作用從原本的環境進到細胞裡

And that only happens efficiently over tiny distances.

那只會有效的發生在短距離內

So for oxygen to reach the cells within our bodies,

所以為了讓氧氣能抵達我們身體的細胞

it needs a transportation network.

就需要一個運輸網路

This is where our 20 trillion red blood cells come in.

那就是我們身體裡20兆個紅血球的用途

Each one contains about 270 million oxygen-binding molecules of hemoglobin,

每個紅血球都包含著27億個血紅素的氧結合分子

which is what gives blood its scarlet hue.

那也是讓血液呈現紅色的原因

To make these cells, the body uses raw materials

為了生成這些細胞

that become available from the food we eat.

身體以我們攝取的食物中作為原料

So in some ways, you could say that oxygen's journey through the body

在某方面，你可以說身體中氧氣的旅程

really begins in the gut.

是從我們的內臟開始的

Here, in an amazing display of mechanical and chemical digestion,

這是一個令人驚奇的機械性及化學性消化作用

food gets broken down into its smallest elements,

食物被分解成更小的粒子

like iron, the building block of hemoglobin.

像是血紅素的基本元素－鐵質

Iron is carried through the cardiovascular system

鐵質是透過心血管系統運送

to the body's hematopoietic tissue.

到身體的造血組織裡

This tissue is the birthplace of red blood cells,

這個組織就是紅血球的來源地

and it can be found enclosed within our bone marrow cavities.

而這也可以在我們的骨髓的空隙中找到

The kidneys regulate our levels of red blood cells

腎臟透過釋放紅血球生成素

through the release of erythropoietin,

來調節紅血球的多寡

a hormone which causes marrow to increase production.

紅血球生成素是刺激骨髓增加紅血球產量的荷爾蒙

Our bodies churn out roughly 2.5 million red blood cells per second,

我們的身體每秒大概會製造出２５０萬的紅血球

a number equivalent to the entire population of Paris,

這數量等同於整個巴黎的人口

so that oxygen that makes it to the lungs will have ample transportation.

所以運送到肺的氧氣會有充足的運送

But before oxygen can even reach the lungs,

但在氧氣到達肺之前，

the brain needs to get involved.

大腦也需要介入

The brainstem initiates breathing

腦幹會藉由神經系統

by sending a message through your nervous system,

傳送開始呼吸的訊息

all the way to muscles of the diaphragm and ribs.

並延續到橫膈膜和肋骨

This causes them to contract,

這訊息讓他們開始收縮

thus increasing the space inside the rib cage,

進而增加肋骨中央的空間

which allows the lungs to expand.

讓肺擴張

That expansion drops your lungs internal air pressure,

擴張會使肺內部的氣壓降低

making air rush in.

讓空氣進入

It's tempting to think of our lungs as two big balloons,

這讓人聯想到我們的肺就像兩顆氣球

but they're actually a lot more complicated than that.

但它們比氣球複雜多了

Here's why.

這裡就要告訴你原因

The red blood cells in the vessels within your lungs

在肺臟血管理的紅血球

can only pick up oxygen molecules that are very close to them.

只能接收離他們非常近的氧分子

If our lungs were shaped like balloons,

如果我們的肺形狀就像氣球

air that was not in direct contact with the balloon's inner surface

那些沒有跟氣球面直接接觸到的氧分子

couldn't diffuse through.

就無法擴散通過

Luckily, our lungs' architecture ensures that very little oxygen is wasted.

幸好，我們肺的結構可以確保只有一些些氧氣會被浪費掉

Their interior is divided into hundreds of millions

它們的內部區隔成上百萬個

of miniature balloon-like projections called alveoli

如小氣球般的凸出，稱做肺泡

that dramatically increase the contact area

那顯然地增加了接觸的面積

to somewhere around 100 square meters.

大約１００平方公尺的面積

The alveolar walls are made of extremely thin flat cells

肺泡壁則是由很多非常薄

that are surrounded by capillaries.

由微血管包圍的細胞組成

Together, the alveolar wall and capillaries make a two-cell thick membrane

肺泡壁和微血管一起形成了兩個細胞壁厚的薄膜

that brings blood and oxygen close enough for diffusion.

足以讓血液及氧氣發生擴散作用

These oxygen-enriched cells are then carried from the lungs

接著這些帶氧的細胞會從肺

through the cardiovascular network,

通到匯集龐大血管的心血管的網絡中

a massive collection of blood vessels that reaches every cell in the body.

使每個細胞到達身體

If we laid this system out end to end in a straight line,

如果我們將這些系統從頭排到尾拉成一直線

the vessels would wrap around the Earth several times.

那些血管可以繞地球好幾圈呢

Propelling red blood cells through this extensive network

將紅血球推進這些龐大的網絡中

requires a pretty powerful pump,

需要非常有力的幫浦

and that's where your heart comes in.

而這就是心臟的用途

The human heart pumps an average of about 100,000 times per day,

人類的心臟每天平均會跳１０萬次

and it's the powerhouse that ultimately gets oxygen where it needs to go,

這個動力室讓氧氣被輸送到需要的地方

completing the body's team effort.

維持身體協調的機能

Just think - this entire complex system is built around the delivery

想一想，這整個複雜的系統建構在一個

of tiny molecules of oxygen.

微小的氧氣分子運輸網絡中

If just one part malfunctioned, so would we.

只要有一部分發生故障，我們就活不了

Breathe in.

吸氣

Your gut, brain, bones, lungs, blood, and heart

你的內臟、大腦、骨頭、肺、血液和心臟

are continuing their incredible act of coordination that keeps you alive.

正持續著它們難以置信的協調合作，來維持你的生命

Breathe out.

吐氣