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  • What's that sound?

    那是什麼聲音?

  • Depending on whom you ask,

    取決於你問誰

  • the crackle of popping joints is either the sound of sweet relief

    當手指關節發出聲音時有可能是舒緩的徵兆

  • or the noxious tones of a stomach-turning habit.

    就是個令人倒盡胃口的習慣

  • Really, though. What's that sound?

    認真的,那到底是什麼聲音?

  • I mean, why does bending your joints in a certain way make them pop like that?

    我的意思是,為什麼在某些方式彎曲你的關節會使他們發出那些聲音?

  • Scientists have offered several explanations,

    科學家提供許多解釋

  • including rapidly stretching ligaments,

    包括迅速伸展韌帶

  • and in severe cases, actual bones grinding against each other.

    若再嚴重一點,便是骨頭互相摩擦的聲音

  • But the most common explanation

    不過最常見的解釋

  • for why your stretched-out joints sound like bubbles popping

    對於你關節伸展時像是泡泡破掉的聲音

  • is that, well, there are bubbles in there.

    其實是...好吧.那裡面的確有泡泡

  • The joints in your fingers are the easiest ones to crack,

    你手指的關節最能夠輕而易舉地發出聲音

  • but many people also crack the joints between vertebrae in their neck and back,

    不過許多人在脖子及背部之間的椎骨也可以發出聲音

  • and even their hips, wrists, shoulders and so on.

    甚至在他們的臀部,手腕,肩膀等等的

  • All these joints are synovial joints,

    這些關節全部都是有滑液的關節

  • and they're the most flexible ones in your body.

    而且他們在你的身體中是最靈活的

  • The space between the two bones is filled with a viscous liquid,

    在兩個骨頭之間的空間充滿了有黏性的液體

  • synovial fluid, which contains long, lubricating molecules,

    關節的液體包含長形潤滑的分子

  • like hyaluronic acid and lubricin.

    像是玻尿酸及關節液糖蛋白

  • Synovial fluid is more or less the texture of egg yolk

    關節液體跟蛋黃很像

  • and its primary purpose is to cushion the bones

    它主要的目的是要緩衝骨頭

  • and help them glide past each other.

    以及幫助骨頭順利互相滑動

  • It also contains phagocytic cells

    它也包含噬菌細胞的細胞

  • that help clean up any bone or cartilage debris that ends up in the joint.

    能夠去除關節裡的骨頭或軟骨碎片

  • But the reason it's important for knuckle cracking

    不過手指關節會有聲音的關鍵是

  • is that, like other fluids in your body,

    正如你身體裡的其他液體

  • it contains lots of dissolved gas molecules .

    它富含許多的溶解的氣體分子

  • Knuckle-crackers know that to get that satisfying pop,

    習慣凹關節的人為了聽到那令人滿足的一聲「喀」

  • you stretch the joint farther than it normally goes

    你折手指的頻率遠超過之前

  • by bending your fingers backwards, for example.

    舉例來說,往後彎曲你的手指

  • When you do that, the bones move away from each other.

    當你那樣做,骨頭會互相移動

  • The space between bones gets bigger,

    骨頭之間的空間會變大

  • but the amount of synovial fluid stays constant.

    不過骨頭的滑液量保持不變

  • That creates a low-pressure zone

    這創建出一個低壓力的區域

  • that pulls dissolved gases out of the synovial fluid,

    會把溶解的氣體分子拉出骨頭的滑液中

  • just like the carbon dioxide that fizzes out of soda

    就像是打開汽水時二氧化碳竄出

  • when you twist open the cap.

    的嘶嘶聲

  • Inside the joint, the escaping gases form a bubble with a pop.

    在關節裡面,氣體從發出聲音的泡泡中跑出

  • But the bubble doesn't last long.

    不過這個泡泡並不會持續太久

  • The surrounding fluid presses on it until it finally collapses.

    周圍的液體會壓迫在上面,使它瓦解

  • The bubble's gases scatter throughout the synovial cavity

    這泡泡的氣體會四處散布在滑液腔中

  • and slowly dissolve back into the fluid over the course of about twenty minutes,

    接著大約在二十分鐘的期間慢慢的溶解進液體中

  • which is why it can take a while before you can pop the same joint again.

    就也是為什麼在你做折手指這相同的動作時需要隔一點時間才能再有聲音

  • Some scientists think there may actually be two pops.

    一些科學家認為事實上會有兩個聲音

  • One when the bubble forms, and another when it bursts.

    一個是當泡泡形成時,另一個則是當它破裂時

  • Popping a joint temporarily enlarges it,

    彈關節會使它短暫的擴大

  • which may be why dedicated knuckle-, neck- and back-crackers

    這也就是折關節、脖子、背部的人

  • say the habit makes their joints feel looser and more flexible.

    說這個習慣會使他們的關節感覺變得比較鬆和易彎曲的

  • But you may have heard from a concerned relative or annoyed officemate

    不過你可能聽過一些來自於關心你的親戚或煩人的同事

  • that cracking your joints will give you arthritis.

    讓關節發出啪聲會使你得關節炎

  • A doctor named Donald Unger heard this, too.

    一位醫生,名字是Donald Unger ,他也聽過這種說法

  • So, determined to disprove his mother's warnings,

    因此,決定要證明他母親的警告是不對的

  • he cracked the knuckles of his left hand repeatedly for 50 years,

    他持續了五十年反覆的使他左手發出啪聲

  • while the right-hand knuckles went unpopped.

    而右手關節則不發出啪聲

  • 36,500 cracks later, both hands were arthritis-free.

    當發出了36,500次啪聲後,兩隻手都沒有得到關節炎

  • For this selfless act of devotion to science,

    這對於科學無私奉獻的舉動

  • Dr. Unger received an Ig Nobel Prize,

    Unger醫生獲頒搞笑諾貝爾獎

  • a parody of the Nobel Prize that recognizes wacky,

    被視為是模仿諾貝爾獎的一個古怪的獎項

  • but weirdly fascinating, scientific accomplishments.

    很新奇,卻也有科學上的成就

  • Unger wrote that his results should prompt investigation into other parental beliefs,

    Unger認為,其他父母的刻板印象應該與這個實驗跟進

  • like the importance of eating spinach.

    像是吃菠菜的重要性

  • The jury's still out on that one.

    而這個至今仍尚未定論

  • As for knuckle-cracking,

    至於讓手指發出啪聲

  • one study suggests that all that joint stretching

    一份研究指出關節發出那樣的啪聲

  • and bubble bursting can cause your hands to swell

    使泡泡爆裂可以造成你的手增大

  • and weaken your grip.

    然後會使你握緊的力量變虛弱

  • But the biggest proven danger seems to be annoying those around you.

    不過證明最大的危險似乎是會令在你身邊的人感到煩躁

What's that sound?

那是什麼聲音?

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B2 中高級 中文 美國腔 TED-Ed 關節 骨頭 發出 泡泡 聲音

【TED-Ed】為什麼你的指關節會有聲響? (Why do your knuckles pop? - Eleanor Nelsen)

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    稲葉白兎 發佈於 2015 年 05 月 28 日
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