How the heart actually pumps blood - Edmond Hui

心臟如何輸送血液 — 艾德蒙·輝 (Edmond Hui)

譯者: Tiffany Wu 審譯者: Regina Chu

For most of history,

長久以來

humans had no idea what purpose the heart served.

人類對心臟的作用可說是一無所知

In fact, the organ so confused Leonardo da Vinci,

這個器官甚至複雜到

讓達文西都放棄去了解它

that he gave up studying it.

Although everyone could feel their own heart beating,

雖然大家都能感受自己的心跳

it wasn't always clear what each thump was achieving.

但是我們並不清楚它跳動的功用

Now we know that the heart pumps blood.

現在我們知道心臟是輸送血液的幫浦

But that fact wasn't always obvious,

但這個現象在以前卻不容易知曉

because if a heart was exposed or taken out,

因為若是暴露心臟或被取出

the body would perish quickly.

身體會迅速死亡

It's also impossible to see through the blood vessels,

而且我們也無法透視血管內部

and even if that were possible,

即使可能

the blood itself is opaque,

血液本身是不透明的

making it difficult to see the heart valves working.

使觀察心臟瓣膜如何運作更加困難

Even in the 21st century,

即使到了 21 世紀

only a few people in surgery teams

只有少數手術人員

have actually seen a working heart.

實際看過跳動中的心臟

Internet searches for heart function,

在網路上搜尋心臟的功能

point to crude models, diagrams

也僅能找到粗略的模型、圖解及動畫

or animations that don't really show how it works.

且都無法確實描述心臟機能

It's as if there has been a centuries old conspiracy

數百年來

amongst teachers and students

老師與學生似乎普遍相信

to accept that heart function cannot be demonstrated.

人類不可能演示心臟的功能

Meaning that the next best thing

意味著只能退而求其次

is simply to cut it open and label the parts.

剖開心臟，給各部位命名

That way students might not fully grasp the way it works,

雖然這樣無法讓學生 完整掌握心臟的功能

but can superficially understand it,

但至少能大概了解其基本構造與功能

learning such concepts as

並學到一些概念

the heart is a four-chambered organ,

像是心臟有四個腔室

or potentially misleading statements like,

或產生一些易誤導的論斷

mammals have a dual-circulation:

例如哺乳動物行雙循環

one with blood going to the lungs and back,

一條輸送血液到肺部，再回到心臟

and another to the body and back.

另一條則輸送血液來回全身

In reality, mammals have a figure-eight circulation.

實際上，哺乳動物 血液循環呈「8」字型

Blood goes from one heart pump to the lungs,

第一次跳動輸送血液來回肺部

back to the second heart pump, which sends it to the body,

然後第二次跳動輸送血液至全身

and then back to the first pump.

如此周而復始

That's an important difference

上述兩種循環的差異非常重要

because it marks two completely different morphologies.

因為這是兩個完全不同的生理形態

This confusion makes many students

許多學生對此感到困惑

wary of the heart in biology lessons,

因而擔憂在生物課上學到心臟構造

thinking it signals an intimidating subject

覺得這是一門恐怖的學科

full of complicated names and diagrams.

學名繁雜，圖解難懂

Only those who end up studying medicine

只有最終學習醫科的學生

compeltely understand how it all actually works.

才完全理清心臟究竟是如何運作的

That's when its functions become apparent

於是心臟功能的謎題逐漸明朗

as medics get to observe the motion of the heart's valves.

歸功於醫學生觀察心臟瓣膜的運作

So, let's imagine you're a medic for a day.

現在想像你是一名醫學生

What you'll need to get started is a whole fresh heart,

你首先會得到一顆新鮮完整的心臟

like one from a sheep or pig.

可以是羊或豬的

Immerse this heart in water

把它浸入水中

and you'll see that it doesn't pump when squeezed by hand.

你會發現即便你擠壓它

它也不會輸水

That's because water doesn't enter the heart cleanly enough

這是因為進入心臟的水還不夠

for the pumping mechanism to work.

導致幫浦功能無法運作

We can solve this problem in an extraordinarly simple way.

要解決這個問題很簡單

Simply identify the two atria and cut them off,

只要找到兩個心房

並將其切除

切到心室上端

trimming them down to the tops of the ventricles.

這樣心臟就看起來不那麼複雜了

This makes the heart look less complicated

because the atria have several incoming veins attached.

因為心房連接著數條靜脈

So without them there, the only vessels remaining

所以切掉心房後

就只剩下兩條主要的動脈

are the two major heart arteries:

the aorta and pulmonary artery,

分別是大動脈與肺動脈

像圓柱一樣豎立在兩心室之間

which rise like white columns from between the ventricles.

It looks -- and really is -- very simple.

這樣看起來也的確就簡單多了

If you run water into the right ventricle from a tap

如果你把水注入右心室

(the left also works, but less spectacularly),

左心室也可以，但是效果沒那麼好

你會看到瓣膜關閉

you'll see that the ventricular valve

tries to close against the incoming stream.

阻擋水流入心室

之後整個心室都被灌滿了水

And then ventricle inflates with water.

Squeeze the ventricle and a stream of water

這時如果你擠壓右心室

水會從肺動脈噴出來

squirts out of the pulmonary artery.

瓣膜有不同的名稱

The ventricular valves, called the tricuspid in the right ventricle

在右心室稱作三尖瓣

and the mitral in the left,

左心室的則是二尖瓣

can be seen through the clear water

注水時

opening and closing like parachutes

瓣膜會像降落傘一樣開合

as the ventricle is rhythmically squeezed.

只要你同時有節奏地擠壓心室

This flow of water mimics the flow of blood in life.

這種水流模擬了血液循環

心臟瓣膜的功能卓越

The valves are completely efficient.

You'll notice they don't leak at all when the ventricles are squeezed.

你會發現擠壓心室時

它完全不會漏水

心臟瓣膜運作時常常閉合

Over time, they also close against each other

with very little wear and tear,

但這過程幾乎沒有磨損

which explains how this mechanism continues to work seamlessly

這解釋了心臟為何 得以長時間完美運作

在人一生中，跳動超過二十億次

for more than 2 billion beats a heart gives in its lifetime.

Now, anyone studying the heart can hold one in their hands,

現在，學習心臟科的人 可以實際拿一顆心臟

讓它跳動

make it pump for real

and watch the action unfold.

藉此觀察心臟的運作過程

So place your hand above your own

你也可以把手放在胸前

and feel its rhymic beat.

感受心臟韻律的跳動

Understanding how this dependable inner pump works

在了解我們賴以生存的心跳如何運作後

gives new resonance to the feeling you get

我們就能更深刻的體會心跳的意義

when you run a race,

不論是跑步

攝取過多咖啡因

drink too much caffeine

or catch the eye of the one you love.

或是與愛人四目相對時