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  • Hi, I'm Adam Cole.

    大家好,我是 Adam Cole。

  • This week we've got a question from Lulu Miller, the host of NPR's Invisibilia podcast:

    本週我們收到美國公共廣播電台《探索未知》節目主持人 Lulu Miller 提出的一個問題:

  • How old are our bodies actually?


  • Because if you think about how we're constantly being regenerated our physical matter is being shed and replenished... what actually remains?


  • Good question, Lulu!

    Lulu 問得好,這是一個很好的問題!

  • Well, your hair obviously doesn't remain the same and I'm not just talking about the style.

    嗯,你的頭髮一定不會永遠不變,我的意思並不是說 「髮型 」會變。

  • Each hair on your head is replaced every 2 to 7 years.

    而是說,你頭上的每根頭髮每 2-7 年會更換一次。

  • A hundred hairs fall out every day and new ones grow back in their place.


  • And look at your fingernails - they're completely new every six months or so.

    看看你的指甲 - 他們大約每 6 個月會完全更新一次。

  • It turns out it's just a matter of time before almost every part of your body refreshes itself in a similar way.


  • The lining of your stomach and intestines gets pretty beat up -- it's constantly exposed to acid and bile and so those cells get replaced every few days.

    你的胃和小腸的內壁細胞被攻擊得非常厲害 - 他們一直暴露在酸和膽鹽的環境中,所以這些細胞每隔幾天就會更新一次。

  • Every few weeks, your outer layer of skin is completely renewed.


  • Every four months you have a fresh army of red blood cells.

    每 4 個月,你會有一批新的紅血球軍團。

  • A hundred million new cells are born every minute and a hundred million old cells are destroyed.


  • It's actually the breakdown products of these red blood cells that turn your bruises and urine yellow.


  • Every 10 years, you've got a new skeleton.

    每 10 年,你會有一個全新的骨骼。

  • A special team of cells breaks down old bone, and another builds new bone.


  • Every 15 years your muscles are refreshed.


  • You might think you gain and lose fat cells when you gain and lose weight but they actually just get bigger and smaller.


  • Over the course of 25 years though, most of them turn over.

    在 25 年的時間內,大部份脂肪細胞都會更新。

  • But there are a few things that stick around for your entire life.


  • About half of your heart stays with you from birth to death because those cells are replaced very slowly.


  • Certain parts of your brain add a few new neurons over the course of your life but the vast majority of your neurons developed before you were born.


  • It's the connections between those neurons -- the circuits that store memories that are constantly changing.


  • And there's one more part of you that lasts your whole life.


  • Months before you were born, a little cluster of cells stretched and filled themselves with transparent protein.


  • As you grew, even after birth, more and more fibers were added, but that center endured


  • This is your lens the window through which you are watching this video right now, and its core has remained the same since the moment you first opened your eyes.


  • So how old is your body really?


  • Some of it is brand-new and some of it is as old as you are.


  • To learn how scientists figured all this out, check out our post at


  • And listen to Invisibilia -- the latest episode is about whether or not personality persists throughout your entire life


  • If you have science questions send them our way and please subscribe to our channel!


Hi, I'm Adam Cole.

大家好,我是 Adam Cole。

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B1 中級 中文 美國腔 細胞 更新 身體 再生 頭髮 脂肪

身體的真實年齡 (Your Body's Real Age)

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    VoiceTube 發佈於 2016 年 09 月 06 日