It's part of the reason we look so feverishly for water on other planets across the universe, and consume it consistently every day here on Earth.

這就是我們迫切尋找宇宙中其他有水源的行星，並每天消耗地球水資源的原因。

So what would happen to your body if you stopped drinking water?

所以，如果停止攝取水份，身體會發生什麼事？

Of course, when we say "water" we're including all fluids which simply contain water - like juices, pop, or tea.

當然，所謂的「水」包含任何可飲用的液體 ，例如果汁、汽水或茶。

Much like the desire to breath in oxygen, thirst is a survival instinct.

感到口渴與吸入氧氣一樣是生存本能。

H2O is the most abundant molecule in the human body making up, on average, 65% of an adult.

水分子佔人體絕大部分，成人體內平均有約 65% 的水分。

As a universal solvent, it carries nutrients and hormones through the body, regulates body temperature, cushions our joints and even lubricates our eyes.

水是萬能溶劑，能幫助身體輸送營養及賀爾蒙、調節體內溫度、緩解關節間的摩擦，甚至能滋潤雙眼。

You produce around 1.5 litres of urine every day, with another litre lost from breathing, sweating and...pooping.

人類每天約排出 1.5 公升的尿液，加上呼吸、流汗或排便也會流失水分。

So it's essential that the body replaces this liquid.

因此，身體如何補充這些水分十分重要。

The thirst centre of the brain is located in the hypothalamus, and is constantly using sensors in your blood vessels to monitor the amount of sodium and other substances in your body.

控管口渴的渴覺中樞位於大腦下視丘，它會不斷地透過血管監測體內鈉和其他物質的含量。

For example, if you sweat too much, your blood volume and pressure fall.

舉例來說，排汗量過多時，血量和血壓都會下降。

The brain then detects this change and creates the urge to drink something, NOW!

大腦偵測到這樣的改變後，就會產生立刻想喝水的欲望。

So what happens if you are unable to satisfy this thirst?

那如果無法止渴會發生甚麼事呢？

The initial signs of dehydration are the obvious dry mouth, following which your urine becomes darker with a stronger odor, as your body attempts to conserve more fluids.

初期脫水會造成明顯的口乾舌燥，接下來尿液會顏色變深並伴隨強烈氣味，因為身體必須減少浪費水分。

The lack of H20 then begins to affect your brain - you may feel light headed, have a slower response time and decreased ability to feel pain.

然後水分缺乏會進而影響到大腦，你可能會感到頭昏眼花、反應遲緩，或是對疼痛感覺麻痺。

In fact, when you're dehydrated, your brain tissue literally shrinks.

事實上，當身體脫水時，大腦組織會逐漸萎縮。

In studies observing hydrated vs. dehydrated participants, the same task required more brain power and oxygen in dehydrated individuals compared to those fully hydrated.

在許多觀察未脫水與脫水受試者反應的觀察中，發現比起水分充足的人，脫水的人需耗費更多腦力與氧氣來完成相同任務。

After a day or two with no fluids, you'll stop peeing all together, have trouble swallowing, suffer from muscle spasms, and likely experience nausea.

若一兩天未攝取水分，身體會減少排尿，並開始感到吞嚥困難、肌肉痙攣及噁心反胃。

After all, your body can survive without food much longer, and attention to digestion is not a priority at this point.

畢竟沒有攝取食物能比缺水存活得更久，所以消化系統在這時並不重要。

Eventually, victims may become delirious with severely impaired brain function.

最終，缺水的人會變得神智不清，大腦功能嚴重受損。

Interestingly, studies looking at elderly patients who suffer from delirium, found that many are simply suffering from chronic dehydration in the first place.

研究發現，年老的神智不清患者多半是一開始歷經了長期脫水。

After even more time without water, the blood stops flowing to your skin, reducing heat loss but increasing your core body temperature.

如果更長一段時間未攝取水分，血液會停止流向皮膚以減少熱能耗損，但身體的核心溫度卻會升高。

This can lead to a grey-blueish tinge to your skin.

這會導致皮膚呈現灰青色。

Beyond 3-5 days without water, and your body will begin to shut down it's organs, and eventually the brain.

而超過三到五天未攝取水份，身體器官就會逐漸衰竭，直到最後大腦也無法運作。

Of course, unlike the plentiful oxygen we breath, only 2.5% of all Earth's water is fresh.

不像氧氣，地球上只有約 2.5% 的乾淨水源。

Most of which is locked up in glaciers, ice caps and underground lakes known as aquifers, leaving less than 1% available for drinking.

且大部分都封藏於冰河、冰冠及地下水層，真正可飲用水剩不到 1%。

And most of this water is actually used to grow crops.

而大部分的水又被用來灌溉穀物。

Approximately 500 billion liters of fresh water is used daily for agriculture in the USA alone, with another 500 billion liters to cool electric power plants.

光以美國為例，每天約有五千億公升的乾淨水源被用做農業灌溉，另外五千億公升的水用來冷卻核燃料棒。

And as our personal drinking sources become increasingly contaminated, over 783 million people on earth are unable to access clean water.

加上飲用水源汙染日益嚴重，地球上約有 7.83 億人無法取得乾淨水源。

Scientists around the world are trying to find solutions to this problem -

科學家正積極想找出這些問題的解決方案--

from attempts to remove salt from ocean water, tap into underground aquifers and creating innovative water filtration systems.

從淡化海水、開發地下水源，到發明創新的濾水系統。

If we look to space, NASA has developed technology for astronauts to turn their urine into water more pure than what we drink on earth.

就太空科技而言，NASA 已發展出一項能淨化太空人尿液的技術，淨化過的水甚至比地球飲用水還乾淨。

But we can't just rely on science and technology - perhaps the solution relies on us as a species to understand and contribute to this global water crisis.

不過僅仰賴科技是不夠的，也許這些問題需要我們深入瞭解的並努力思考全球水資源危機，才可能解決。

If you want to help in the mission to end global thirst, join in World Water Day on March 22nd.

如果你想為地球盡一份心力，來參加 3 月 22 號的世界水資源日吧！

There are a lot of really amazing projects out there, like Water.org or even the awesome UNICEF app, which donates 1 day of clean water to child in need for every 10 minutes you put your phone down.

那裡有很多有趣的企劃，例如 Water.org 或是 UNICEF (聯合國兒童基金會) 的應用程式。你每放下手機 10 分鐘，他們就會捐贈一天份量的乾淨水資源給需要的小孩。

We'll leave links in the description for these and other great water charities.

我們會在說明區中留下相關連結。

Small investments really do make a huge difference.

小小的愛心能轉動整顆地球。

We'll be donating all the proceeds from this video to a water project close to us called Morocco 5 Villages - so thanks for supporting and watching.

我們會將這支影片所得捐贈給「摩洛哥的 5 個村莊」水資源計畫，感謝您的支持與收看。

And subscribe for more weekly science videos!

訂閱頻道，並收看更多每週科學影片！