How do your kidneys work? - Emma Bryce

腎臟是如何運轉的? - Emma Bryce

譯者: An Lin 審譯者: Peipei Xiang

It's a hot day,

在炎熱的一天

and you've just downed several glasses of water,

你喝下了好幾杯的水

one after the other.

一杯接著一杯

Behind the sudden urge that follows are two bean-shaped organs

很快你感受到一股慾望（上廁所）， 這突然的慾望背後是兩個豆子形狀的器官

that work as fine-tuned internal sensors.

它們是保持體內和諧的感應器

They balance the amount of fluid in your body,

它們除了平衡身體裡的水量

detect waste in your blood,

也能感測血液中的廢物

and know when to release the vitamins, minerals,

還能知道何時該釋放出 能讓你維繫生命的維他命

and hormones you need to stay alive.

礦物質和賀爾蒙

Say hello to your kidneys.

向你的腎臟說嗨吧！

The main role of these organs is to dispose of waste products

腎臟的主要功能就是清除廢物

and to turn them into urine.

並且把廢物轉換成尿液

The body's eight liters of blood pass through the kidneys

身體裡八公升的血液

每天通過腎臟約20-25次

between 20 and 25 times each day,

meaning that, together, these organs filter about 180 liters every 24 hours.

也就是說，這對器官在24小時內 總共過濾了180公升的血

The ingredients in your blood are constantly changing

血液中的成分隨著吸收食物和飲料

as you ingest food and drink,

不斷地變化其中的成分

which explains why the kidneys need to be on permanent duty.

這也解釋了為什麼腎臟 必須無時無刻的運作

Blood enters each kidney through arteries that branch and branch,

血液透過分支的動脈來進入腎臟

until they form tiny vessels that entwine with special internal modules,

動脈分支形成很細小的血管 纏繞一個很特別的內部單元

called nephrons.

這個結構叫做腎元

In each kidney,

在每個腎臟中

1 million of these nephrons form a powerful array of filters and sensors

這一百萬個腎元形成 有力的感應器和過濾器部隊

that carefully sift through the blood.

它們小心翼翼地篩檢血液

This is where we see just how refined

我們可以由此看出

這內部感應系統是多麼的優良和精確

and accurate this internal sensing system is.

To filter the blood, each nephron uses two powerful pieces of equipment:

為了過濾血液 每個腎元有兩個有強而有力的結構

a blob-like structure called a glomerulus, and a long, stringy, straw-like tubule.

其中一個像水滴的叫做腎小球 另一個長形像繩子一樣的叫做腎小管

The glomerulus works like a sieve, allowing only certain ingredients,

腎小球就像篩子 只容許少數特定成分通過並進入腎小管

such as vitamins and minerals, to pass into the tubule.

例如維他命和礦物質

Then, this vessel's job is to detect

接著，腎小管的工作就是要感測

whether any of those ingredients are needed in the body.

這些成分中有哪些是身體所需要的

If so, they're reabsorbed in amounts that the body needs,

若需要，它們會依需求量被再吸收

so they can circulate in the blood again.

所以它們能夠再回到血液中循環

But the blood doesn't only carry useful ingredients.

但是血液不僅僅攜帶有用的成分

It contains waste products, too.

它也含有廢物

And the nephrons have to figure out what to do with them.

腎小元必須要釐清該如何處理它們

The tubules sense compounds the body doesn't need,

腎小管會感應出體內不需要的成分

like urea, left over from the breakdown of proteins,

像是尿素、蛋白質分解後的殘留物等等

and redirects them as urine out of the kidneys

並且把這些廢物改作尿液排出腎臟

and through two long sewers called ureters.

經過稱為輸尿管的兩條長形通道

The tubes empty their contents into the bladder to be discharged,

輸尿管把廢物移到膀胱，等待被排出體外

ridding your body of that waste once and for all.

一勞永逸的把廢物全部排出

There's water in that urine, too.

在尿液中也有水

If the kidney detects too much of it in your blood,

如果腎臟感測到太多水分在你的血液當中

for instance, when you've chugged several glasses at once,

舉例來說，如果你一口氣灌下好幾杯的水

it sends the extra liquid to the bladder to be removed.

腎臟會將多餘的水分送到膀胱等待排出

On the other hand, low water levels in the blood

另一方面來說，血液中的水分如果太少

prompt the kidney to release some back into the blood stream,

會刺激腎臟釋放回一些水分到血液中

meaning that less water makes it into the urine.

意味著尿液中的水分也會比較少

This is why urine appears yellower when you're less hydrated.

這也是為什麼尿液在人體較缺水時 會呈現較黃的顏色

By controlling water, your kidneys stabilize the body's fluid levels.

腎臟控制水分來穩定體內的液體含量

But this fine balancing act isn't the kidney's only skill.

不過，這個完美的平衡並不是腎臟唯一能做的

These organs have the power to activate vitamin D

腎臟還擁有活化維他命D的功能

to secrete a hormone called renin that raises blood pressure,

還能夠分泌一種叫做腎素的荷爾蒙 它能夠提高血壓

and another hormone called erythropoietin,

還能分泌另一種叫做 紅血球生成素的賀爾蒙

which increases red blood cell production.

用來增加紅血球產量

Without the kidneys, our bodily fluids would spiral out of control.

沒有腎臟，我們體內的液體會失去控制

Every time we ate, our blood would receive another load of unsifted ingredients.

我們每次吃東西 我們的血液都會接受到一批未篩檢的成分

Soon, the buildup of waste would overload our systems and we'd expire.

很快的，堆積的廢物增加了器官系統的負擔 導致我們死亡

So each kidney not only keeps things running smoothly.

所以腎臟不僅僅讓體內運轉順暢

It also keeps us alive.

它還維繫了我們的生命

Lucky then that we have two of these magical beans.

我們真是幸運，擁有兩個如此神奇的豆子!