How mucus keeps us healthy - Katharina Ribbeck

譯者: May Wu 審譯者: Pechow Z

If you've got a cold, mucus is hard to miss.

當你感冒時，黏液無處不在。

But what is it, and what does it do besides making you miserable?

但黏液到底是甚麼? 它除了讓你難受外還有何作用呢?

Your body produces more than a liter of mucus every day,

你的身體每天都會製造一公升以上的黏液，

and all the wet surfaces of your body that are not covered by skin,

身體部位沒有被皮膚覆蓋的濕的表面

like your eyes,

例如你的眼睛，

nose,

鼻子，

mouth,

嘴巴，

lungs,

肺部，

and stomach get a liberal coating.

還有胃部 都有一層與外界聯通的膜，

That's why they're known as mucus membranes.

所以它們也被稱之為黏膜。

Mucus plays lots of roles in your body.

黏液在你身體裡有許多作用，

It keeps delicate tissues from drying out and cracking,

它防止嬌嫩的組織乾裂，

which would expose them to infection.

進而防止它們受到感染。

It lubricates your eyes so you can blink.

它濕潤你的眼睛使你能夠眨眼。

It protects your stomach lining from acid.

它保護你的胃內層不會受到胃酸的侵襲。

It neutralizes threats by removing or trapping substances

它能移除或攔阻

that could make you sick.

會使你生病的物質。

And finally, it houses and keeps your body's trillions of bacterial inhabitants,

還有，它使你體內數以萬計的細菌，

your microbiota, under control.

還有微生物可以得到控制。

Mucus contains lots of different compounds,

黏液中有許多不同的化合物，

including proteins, fats, and salts.

例如蛋白質、脂肪，和鹽。

But a key component of mucus versatility is a set of proteins called mucins.

但是黏液的多功能主要 來自於一組稱為"黏蛋白"的蛋白質。

Mucins are the primary large molecules in mucus

黏蛋白是黏液中最大的分子

and are essential for giving mucus its slippery feel.

它們讓黏液有滑溜的感覺。

They belong to a class of proteins called glycoproteins

黏蛋白是屬於糖蛋白的一種，

which are built out of both amino acids and sugars.

糖蛋白是由胺基酸和糖分所組成。

In mucin, long chains of sugars are attached to specific amino acids

在黏蛋白裡，一長串的糖 會黏著於特定的氨基酸

in the protein backbone.

位於蛋白質的骨幹。

The hydrophilic sugar chains help mucin dissolve in your body's watery fluids.

水糖鏈幫助粘蛋白溶解於你身體內的液體。

Mucus, which is up to 90% water,

有九成以上都是水分的黏液

stays hydrated thanks to these sugar chains.

因為水糖鍊而能得以保存水分。

Some of these mucins can interact with other mucin molecules

有些黏蛋白可以透過 與其他的黏蛋白分子的互動

to create a complex network that establishes a barrier

來創建複雜網絡並建立屏障

against pathogens and other invaders.

用來阻隔病原體和其他入侵者。

That's why mucus is the body's first line of defense against foreign objects,

這就是為什麼粘液是人體的第一道防線，

like bacteria and dust.

可抵禦如細菌和粉塵的外來物。

It's continuously produced to clear them from the respiratory tract,

黏液的連續生產可將外來物從呼吸道清除，

like a slimy conveyor belt.

像一條粘糊糊的傳送帶。

This keeps bacteria from getting a solid purchase on delicate lung tissue,

這樣可以防止細菌嚴重感染脆弱的肺組織，

or making it to the blood stream, where they could cause a major infection.

或跑入血流並進一步引起重大感染。

Many of those harmful bacteria also cause diseases

其中許多有害細菌還會引起疾病，

when they cluster into slimy growths called biofilms.

當他們聚集並凝結成為生物膜。

But mucus contains mucins,

但粘液中含有黏蛋白，

antimicrobial peptides,

抗菌肽，

antibodies,

抗體，

and even bacteria-hungry viruses called bacteriophages

甚至有被稱為噬菌體的以細菌為食的病毒，

that all work together to prevent biofilms from forming.

他們合作無間，阻止生物膜的產生。

If microbes do become harmful and you get sick,

如果微生物成為有害的病使你生病，

the body ramps up mucus production to try to quickly flush out the offenders,

身體會大量製造黏液 以求盡速地清除掉入侵者，

and the immune system floods your mucus with extra white blood cells.

免疫系統也會為黏液補充額外的白血球。

In fact, the greenish mucus often associated with infections

事實上，綠色黏液 (常被人們與感染相聯繫的)

gets its color from an enzyme produced by those white blood cells.

是從白血球製造的酶獲得它的顏色。

This multi-pronged approach to bacterial management

這種多管齊下的細菌管理

is one of the main reasons why we're not sick all the time.

是我們不會常常生病的主因。

Even though mucus protects against the infectious bacteria,

儘管粘液能夠防止有感染性的細菌，

the vast majority of your body's bacterial tenants are not harmful,

我們體內的細菌絕大多數不是有害的，

and many are actually beneficial.

許多甚至是對我們有益處的。

That's particularly true when they live in mucus,

尤其當細菌住在黏液中時，

where they can perform important functions,

他們可以執行重要的功能，

like synthesizing vitamins,

例如合成維生素，

suppressing harmful inflammation,

抑制有害的炎症，

and controlling the growth of more harmful species.

和控制有害物質的生長。

So even though you probably associate mucus with being ill,

因此，雖然你可能會把 黏液與生病聯繫起來，

it's really helping you stay healthy.

它其實可以幫助你維持健康。

Sure, it might seem gross,

當然，它感覺有點噁心，

but can you think of any other substance that can lubricate,

但你能想到任何其他可以幫助潤滑的物質，

keep your body clean,

同時也可以保持你體內的乾淨，

fight infection,

抵抗感染，

and domesticate a teeming bacterial population?

和馴服孳生的細菌群體嗎？

Nope, just mucus.

不。只有黏液做得到。