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  • What do Charles Darwin, Michael Jordan, and Yoda have in common?

    チャールズ・ダーウィン、マイケル・ジョーダン、ヨーダには、<a href="#post_comment_1">共通点<i class="icon-star"></i>があるのでしょうか?

  • They, like many other historical and fictive individuals, are bald, in some cases by their own choice.


  • For centuries, a shining dome has been a symbol of intelligence, but despite this, many balding people still wish their hair would return.


  • Scientists have long pondered, "Why do some people lose their hair, and how can we bring it back?"

    科学者たちは長い間、<a href="#post_comment_2">pondered<i class="icon-star"></i>, "なぜ髪の毛を失う人がいるのか、どうすれば髪の毛を取り戻すことができるのか?"と考えてきました。

  • The full-headed among us have about 100,000 to 150,000 hairs on our scalps, and scientists have discovered two things about this dense thicket.


  • Firstly, the sprouting hair we see is mostly made up of keratin, the protein leftover from dead cells that are forced upwards as new cells grow beneath them.


  • Secondly, the structures that drive hair growth are called hair follicles, a network of complex organs that forms before we're born, and grows hair in an everlasting cycle.


  • This cycle has three main phases.


  • The first is anagen, the growth phase, which up to 90% of your hair follicles are experiencing right now, causing them to push up hair at a rate of one centimeter per month.


  • Anagen can last for two to seven years, depending on your genes.


  • After this productive period, signals within the skin instruct some follicles to enter a new phase known as catagen, or the regressing stage, causing hair follicles to shrink to a fraction of their original length.

    この生産期間の後、皮膚内の信号は、いくつかの毛包が<a href="#post_comment_3">a fraction of<i class="icon-star"></i>元の長さに縮むことを引き起こし、カタゲンとして知られている新しい段階に入るように指示します。

  • Catagen lasts for about two to three weeks and cuts blood supply to the follicle, creating a club hair, meaning it's ready to be shed.


  • Finally, hairs enter telogen, the resting phase, which lasts for ten to twelve weeks, and affects about 5-15% of your scalp follicles.


  • During telogen, up to 200 club hairs can be shed in a day, which is quite normal.


  • Then, the growth cycle begins anew.


  • But not all heads are hairy, and, in fact, some of them grow increasingly patchy over time in response to bodily changes.

    しかし、すべての頭が毛深いわけではなく、実際には、身体の変化に応じて時間をかけて<a href="#post_comment_4">patchy<i class="icon-star"></i><a>どんどん成長していくものもあります。

  • 95% of baldness in men can be attributed to male pattern baldness.


  • Baldness is inherited, and in people with this condition, follicles become incredibly sensitive to the effects of dihydrotestosterone, a hormonal product made from testosterone.


  • DHT causes shrinkage in these overly sensitive follicles, making hair shorter and wispier.


  • But loss isn't sudden.


  • It happens gradually, along a metric known as the Norwood Scale, which describes the severity of hair loss.


  • First, hair recedes along the temples, then hair on the crown begins to thin in a circular pattern.


  • At the highest rating on the scale, these balding areas meet and expand dramatically, eventually leaving only a ring of sparse hair around the temples and the back of the head.


  • Genetics isn't all that drives hair loss.


  • Long periods of stress can release signals that shock follicles and force them into the resting phase prematurely.


  • Some women experience this after childbirth.


  • Follicles might also lose the ability to go into anagen, the growth phase.


  • People going through chemotherapy treatment temporarily experience this.


  • But while balding may look permanent, scientific investigation has revealed the opposite.


  • Below the skin's surface, the roots that give rise to our hair actually remain alive.


  • Using this knowledge, scientists have developed drugs that shorten the resting phase, and force follicles into anagen.


  • Other drugs combat male pattern baldness by blocking the conversion of testosterone to DHT so that it doesn't affect those sensitive follicles.

    他の薬は、それらの敏感な卵胞に影響を与えないように、テストステロンの DHT への変換をブロックすることによって男性のパターンのハゲと戦う。

  • Stem cells also play a role in regulating the growth cycle, and so scientists are investigating whether they can manipulate the activity of these cells to encourage follicles to start producing hair again.


  • And in the meantime, while scientists hone their hair-reviving methods, anyone going bald, or considering baldness, can remember that they're in great company.

    そしてその間に、科学者たちは彼らの髪の復活の方法を磨きながら、誰もがハゲに行く、またはハゲを考慮して、<a href="#post_comment_5">they're in great company<i class="icon-star"></i>を覚えていることができます</a>。

What do Charles Darwin, Michael Jordan, and Yoda have in common?

チャールズ・ダーウィン、マイケル・ジョーダン、ヨーダには、<a href="#post_comment_1">共通点<i class="icon-star"></i>があるのでしょうか?


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B2 中上級 日本語 TED-Ed ハゲ 髪の毛 毛包 成長 サイクル

TED-ED】なぜハゲる人がいるのか?- サルタク・シンハ

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    SylviaQQ に公開 2015 年 09 月 06 日