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Kurzgesagt (In a Nutshell), Tiny Bombs in your Blood - The Complement System

Tiny Bombs in your Blood - The Complement System

Every living being needs to fight off other living beings that want to feast on them.​

So as multicellular life evolved over billions of years, it came up with ways to defend itself.​

Today humans have a sophisticated defense network,​

like physical barriers, defense cells, and weapons factories.​

But one of the most important defenses of our body is largely unknown:​

The Complement System​

It evolved over 700 million years ago and is an army of over 30 different proteins​

that work together in a complex and elegant dance to stop intruders.​

All in all, about 15 quintillion of them are saturating every fluid in your body right now.​

Guided by nothing but chemistry,​ these proteins are one of the most effective weapons we have against invaders.​ Many other parts of the immune system are just tools to activate the Complement System.​

But it's also really dangerous.​

Imagine having trillions of little bombs inside your blood that could go off at any moment.​

So our cells use numerous mechanisms to prevent​ ​complement from accidentally attacking ​ ​ them​ .​

Okay, what exactly does it do and what makes it so dangerous?​

In a nutshell, The Complement System does three things:​

it cripples enemies, it activates the immune system, and it rips holes in things until they die.​

But, how?​

After all, these are mindless proteins randomly drifting around without will or direction.​

Well, this is actually part of the strategy.​

Complement proteins float around in a sort-of passive mode.​

They do nothing, until they get activated and change their shape.​

In the world of proteins, your shape determines what you can and cannot do.​

Because shape determines what you can interact with and in what way.​

For example, in your passive shape you might do nothing.​

In your active shape, however, you might, for example, change the shape of other proteins​

activating them so they can activate others.​

Mechanisms like this one can start cascades that spread very quickly.​

Imagine the complement proteins as being like millions of matches very close together.​

Once one catches fire, it ignites the ones around it.​

They ignite more and suddenly you have a big fire.​

To show the actual mechanisms of The Complement System is a tad complicated and overwhelming.​

So, we'll simplify here.​

Now, let's imagine you cut yourself and a bunch of bacteria enter the wound​

and make it into the surrounding tissue.​

Our complement attack begins with C3.​

C3 is the first match, the initial spark that will start our fire.​

And to do that, C3 needs to switch from passive to active.​

How this happens is complex, but let's just say it can happen randomly​

through other complement proteins that bind to enemies or through antibodies.​

All you really need to know is that C3 breaks into two smaller proteins,​

C3a and C3b, that are now activated.​

One of these parts, the C3b protein, is like a seeker missile specialized in bacteria, fungi, and viruses.​

It has a fraction of a second to find a victim or it will be neutralized by water molecules.​

If C3b does find a target, it anchors itself very tightly to its surface and doesn't let go.​

By doing so, the protein changes its shape again.​

In its new shape, it's now able to grab other proteins and start a small cascade,​

changing its shape multiple times, adding other complement proteins to itself.​

Finally, it transforms itself into a recruiting platform known as C3 Convertase.​

This platform is an expert at activating more C3 proteins that start the whole cycle anew.​

An amplification loop begins.​

Soon, thousands of proteins cover the bacteria.​

For the bacteria, this is very bad.​

It can cripple the bacteria and make them helpless, or slow them down.​

Imagine being covered by thousands of flies.​

But, there's more.​

Do you remember the other part of C3—the C3a protein?​

C3a is like a distress beacon.​

Thousands of them flood away from the site of battle screaming for attention.​

Passive immune cells notice the C3a proteins,​

and awaken from their slumber to follow the protein tracks to the site of infection.​

The more alarm proteins they encounter, the more aggressive they get.​

This way, complement guides reinforcements exactly to the place where they're needed the most.​

So far, the complement has slowed down the invaders and called for help.​

Now, it's beginning to actively help to kill the enemy.​

The first immune cells to arrive at the battlefield are ​ ​ phagocytes​ .​

Which means, cells that swallow you whole, trap you in a tiny prison, and then kill you with acid.​

But, to swallow an enemy, they need to grab it first.​

Which is not easy because bacteria prefer not to be grabbed and are sort-of slippery.​

But now, the complement that has anchored itself to the bacteria​

acts as a sort-of glue that makes it easy for the immune cells to catch their victims.​

But it gets even better.​

Imagine being covered in flies again.​ Now, imagine them turning into wasps.​ Another cascade is about to begin.​

On the surface of a bacteria, the C3 recruitment platform changes its shape again​

and begins to recruit new proteins.​

Together, they begin the construction of a bigger structure: a Membrane Attack Complex.​

Piece-by-piece, new proteins shaped like long spears anchor themselves deep into the bacteria's membranes,​

until they rip a hole into them that can't be closed again.​

Fluids rush into the bacteria and their insides spill out.​

They bleed to death.​

The remaining bacteria are maimed and distracted by the complement,​

and quickly taken care of by the arriving immune cells.​

The invasion has been nipped in the bud before it had the opportunity to become dangerous.​

You probably didn't even notice it.​

But while bacteria are not happy about complement,​

the enemies it might be the most useful against are actually viruses.​

Viruses have one problem: they need to travel from cell to cell.​

Outside of cells, they're basically hoping to randomly bump against a cell to infect by pure chance.​

Here, they're completely defenseless.​

And here, complement is able to intercept and cripple them,​

so they become harmless and guide the immune system to devour them.​

Without complement, virus infections would be a lot more deadly.​

But wait, if we have such an effective weapon, why do we ever get sick?​

The problem is that in a war, both sides adapt.​

For example, when the ​ ​ vaccinia virus​ infects a cell,​

it forces it to produce a protein that shuts complement activation down.​

This way, the virus creates safe zones around the cells it infects.​

When it kills them, and tries to infect more, it has a higher chance of being successful.​

Or some bacteria, for example, can grab certain molecules from the blood that keep the complement system calm​

and make themselves invisible.​

So the complement system, while being extremely important,​

is only one player in the complex and beautiful organization that is our immune system.​

A beautiful example of how many mindless things can do smart things together.​

This video was sponsored by ​ ​ you​ .​

Without your direct support, this channel would not exist.​

And it's hard to overstate how grateful we are for that.​

In 2019, an average kurzgesagt video took at least 1200 hours to produce.​

We need months to research and write our scripts, clear them with experts,​

illustrate and animate every scene from scratch, and to compose original music.​

This is only possible through a combination of sponsorships,​

your support on Patreon, and selling merch​

like this poster and postcards we made about The Complement System.​

If you, yourself, want to support us,​

you can do so by watching, becoming a Patreon, and maybe getting a personal bird.​

Or, by getting one of our calendars or posters.​

The purpose of kurzgesagt is to make the best videos we can​

and to make science more approachable.​

Thank you so much for making this possible.​

​​

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Tiny Bombs in your Blood - The Complement System ||||||Komplementsystem| ||||||補体系| Winzige Bomben im Blut - Das Komplementsystem Pequeñas bombas en la sangre - El sistema del complemento De petites bombes dans le sang - Le système complémentaire 血液中の小さな爆弾 - 補完システム 혈액 속의 작은 폭탄 - 보체 시스템 Maleńkie bomby we krwi - układ dopełniacza Pequenas bombas no sangue - O sistema do complemento Крошечные бомбы в вашей крови - система комплемента Kanınızdaki Minik Bombalar - Tamamlayıcı Sistem Крихітні бомби у вашій крові - система комплементу 血液中的小炸弹——补体系统 血液中的小炸彈——補體系統

Every living being needs to fight off other living beings that want to feast on them.​ |||||||||Lebewesen||||sich laben|| Todo ser vivo necesita luchar contra otros seres vivos que quieren darse un festín con él. Todo ser vivo precisa lutar contra outros seres vivos que querem se banquetear com eles. Каждое живое существо должно бороться с другими живыми существами, которые хотят полакомиться им.

So as multicellular life evolved over billions of years, it came up with ways to defend itself.​ ||mehrzelliges|||||||||||||verteidigen| |||||||||||||||protect itself| Así que, a medida que la vida multicelular evolucionó durante miles de millones de años, ideó formas de defenderse. Então, à medida que a vida multicelular evoluiu ao longo de bilhões de anos, surgiu maneiras de se defender. По мере того как многоклеточная жизнь развивалась на протяжении миллиардов лет, она придумывала способы самозащиты.

Today humans have a sophisticated defense network,​ ||||||Netzwerk Die Menschen verfügen heute über ein ausgeklügeltes Verteidigungsnetz. Hoy en día, los humanos disponen de una sofisticada red de defensa.

like physical barriers, defense cells, and weapons factories.​

But one of the most important defenses of our body is largely unknown:​ ||||||Abwehrmechanismen|||||weitgehend|unbekannt

The Complement System​ |补体系统| Das||

It evolved over 700 million years ago and is an army of over 30 different proteins​

that work together in a complex and elegant dance to stop intruders.​ |||||||eleganten|Tanz||| die in einem komplexen und eleganten Tanz zusammenarbeiten, um Eindringlinge aufzuhalten.

All in all, about 15 quintillion of them are saturating every fluid in your body right now.​ ||||千万亿||||充满||||||| Alles in allem||||Billiarden||||durchdringen||Flüssigkeit||||| ||||15京||||||||||| ||||nghìn tỷ||||bão hòa||||||| Alles in allem sind etwa 15 Quintillionen von ihnen in jeder Flüssigkeit in Ihrem Körper. Ao todo, cerca de 15 quintilhões deles estão saturando todos os fluidos do seu corpo agora. В общей сложности около 15 квинтиллионов из них насыщают сейчас все жидкости в вашем организме.

Guided by nothing but chemistry,​ these proteins are one of the most effective weapons we have against invaders.​ Geleitet|||||||||||||||||Eindringlinge Guiadas únicamente por la química, estas proteínas son una de las armas más eficaces que tenemos contra los invasores. 化学のみに導かれ、これらのタンパク質は侵入者に対抗する私たちの最も効果的な武器の1つです。 Many other parts of the immune system are just tools to activate the Complement System.​ 免疫系の多くの他の部分は、補体系を活性化するためのツールにすぎません。

But it's also really dangerous.​ Aber|||| しかし、それは同時に非常に危険でもあります。

Imagine having trillions of little bombs inside your blood that could go off at any moment.​ Imagine ter trilhões de pequenas bombas dentro do seu sangue que podem explodir a qualquer momento. Представьте себе, что в вашей крови находятся триллионы маленьких бомб, которые могут взорваться в любой момент.

So our cells use numerous mechanisms to prevent​ ​complement from accidentally attacking ​ ​ them​ .​ ||||zahlreiche|Mechanismen|||Komplementsystem||versehentlich|angreifen| Unsere Zellen nutzen also zahlreiche Mechanismen, um zu verhindern, dass Komplementärstoffe sie versehentlich angreifen. Por ello, nuestras células utilizan numerosos mecanismos para evitar que el complemento las ataque accidentalmente .

Okay, what exactly does it do and what makes it so dangerous?​ Bien, ¿qué hace exactamente y qué lo hace tan peligroso?

In a nutshell, The Complement System does three things:​ In a nutshell, The Complement System does three things:​

it cripples enemies, it activates the immune system, and it rips holes in things until they die.​ |gây tê liệt||||||||||||||| |verkrüppelt|||aktiviert||||||reißt Löcher|||||| |敵を無力化|||||||||引き裂く|||||| ||||||||||撕裂|||||| Es verkrüppelt Feinde, es aktiviert das Immunsystem, und es reißt Löcher in Dinge, bis sie sterben. paraliza a los enemigos, activa el sistema inmunológico y agujerea las cosas hasta que mueren. ele paralisa os inimigos, ativa o sistema imunológico e abre buracos nas coisas até que elas morram. он калечит врагов, активирует иммунную систему и проделывает дыры в предметах, пока они не умрут.

But, how?​

After all, these are mindless proteins randomly drifting around without will or direction.​ nach allem||||gedankenlos||zufällig|umhertreiben|||Willen|| |||||||漂っている||||| Schließlich handelt es sich um geistlose Proteine, die willen- und ziellos umherschwirren. Al fin y al cabo, se trata de proteínas sin sentido que vagan aleatoriamente sin voluntad ni dirección. Afinal, essas são proteínas irracionais vagando aleatoriamente sem vontade ou direção.

Well, this is actually part of the strategy.​ |||||||Strategie Bueno, esto es en realidad parte de la estrategia.

Complement proteins float around in a sort-of passive mode.​ ||||||||passiven Modus|passiven Modus Komplementproteine bewegen sich in einer Art passivem Modus.

They do nothing, until they get activated and change their shape.​

In the world of proteins, your shape determines what you can and cannot do.​ |||||||bestimmt|||||| |||||||決定する|||||| En el mundo de las proteínas, tu forma determina lo que puedes y no puedes hacer.

Because shape determines what you can interact with and in what way.​ ||決定する|||||||||

For example, in your passive shape you might do nothing.​ |||||||könntest||

In your active shape, however, you might, for example, change the shape of other proteins​

activating them so they can activate others.​ aktivieren|||||| 活性化する||||||

Mechanisms like this one can start cascades that spread very quickly.​ ||||||连锁反应|||| ||||||Kaskaden||sich ausbreiten|| ||||||連鎖反応|||| Mecanismos como este podem iniciar cascatas que se espalham muito rapidamente.

Imagine the complement proteins as being like millions of matches very close together.​ |||||||||Streichhölzer||| Stellen Sie sich die Komplementproteine wie Millionen von Streichhölzern vor, die dicht beieinander liegen. Imagine as proteínas do complemento como milhões de fósforos muito próximos uns dos outros. Представьте, что белки комплемента похожи на миллионы спичек, расположенных очень близко друг к другу.

Once one catches fire, it ignites the ones around it.​ |||||点燃|||| Einmal||fängt|||entzündet|||| |||||引火する|||| |||||bùng cháy|||| Cuando uno se incendia, prende fuego a los que le rodean. Uma vez que um pega fogo, incendeia os que estão ao seu redor.

They ignite more and suddenly you have a big fire.​ |entzünden|||||||| |火がつく|||||||| Eles acendem mais e de repente você tem um grande incêndio.

To show the actual mechanisms of The Complement System is a tad complicated and overwhelming.​ |||||||||||ein wenig|||überwältigend |||||||||||少し||| Die tatsächlichen Mechanismen des Komplementsystems darzustellen, ist ein wenig kompliziert und überwältigend. Mostrar los mecanismos reales del Sistema Complementario es un poco complicado y abrumador. Mostrar os mecanismos reais do Sistema Complemento é um pouco complicado e esmagador. Показать реальные механизмы работы The Complement System довольно сложно и накладно.

So, we'll simplify here.​ ||vereinfachen| ||簡単にします|

Now, let's imagine you cut yourself and a bunch of bacteria enter the wound​ Agora, vamos imaginar que você se corta e um monte de bactérias entra na ferida

and make it into the surrounding tissue.​ y llegar al tejido circundante. e torná-lo no tecido circundante.

Our complement attack begins with C3.​ 私たちの補完攻撃はC3から始まります。

C3 is the first match, the initial spark that will start our fire.​ ||||||anfänglicher Funke|Funke||||| C3 es la primera cerilla, la chispa inicial que encenderá nuestro fuego. C3は最初のターゲットであり、私たちの火を起こす最初の火花です。 C3 é a primeira partida, a faísca inicial que iniciará nosso fogo.

And to do that, C3 needs to switch from passive to active.​ そして、そのためには、C3は受動的から能動的に切り替える必要があります。

How this happens is complex, but let's just say it can happen randomly​

through other complement proteins that bind to enemies or through antibodies.​ a través de otras proteínas del complemento que se unen a los enemigos o a través de anticuerpos. C3が敵に結合する他の補完タンパク質や抗体を介して、 através de outras proteínas do complemento que se ligam a inimigos ou através de anticorpos.

All you really need to know is that C3 breaks into two smaller proteins,​ 知っておく必要があるのは、C3が2つの小さなタンパク質であるC3aとC3bに分解されるということです。

C3a and C3b, that are now activated.​ C3a y C3b, que ahora están activados. これらは今活性化されています。

One of these parts, the C3b protein, is like a seeker missile specialized in bacteria, fungi, and viruses.​ ||||||||||||||||||病毒 |||||||||||Sucher|Lenkwaffe|||||| ||||||||||||ミサイル|||||| Uma dessas partes, a proteína C3b, é como um míssil de busca especializado em bactérias, fungos e vírus.

It has a fraction of a second to find a victim or it will be neutralized by water molecules.​ |||||||||||||||中和||| |||Bruchteil|||||||Opfer|||||neutralisiert|||Wassermoleküle |||||||||||||||無力化される||| Tiene una fracción de segundo para encontrar una víctima o será neutralizado por las moléculas de agua.

If C3b does find a target, it anchors itself very tightly to its surface and doesn't let go.​ ||||||||neo|||||||||| ||||||||verankert sich|||||||||| ||||||||固定する|||||||||| Si el C3b encuentra una diana, se ancla muy fuertemente a su superficie y no la suelta.

By doing so, the protein changes its shape again.​

In its new shape, it's now able to grab other proteins and start a small cascade,​ ||||||||greifen|||||||kleine Kaskade starten |||||||||||||||連鎖反応 新しい形状に変わると、他のタンパク質をつかんで小さなカスケードを開始できるようになりました。

changing its shape multiple times, adding other complement proteins to itself.​ |||||hinzufügen||||| cambiando su forma varias veces, añadiéndose a sí misma otras proteínas del complemento. 形状を何度も変え、他の補完タンパク質を自身に追加します。

Finally, it transforms itself into a recruiting platform known as C3 Convertase.​ ||biến đổi||||tuyển dụng||||| ||verwandelt sich in||||Rekrutierungsplattform|Plattform||||C3-Konvertase-Plattform ||変化する||||||||| |||||||||||转化酶 最終的に、C3コンバテーゼとして知られるリクルーティングプラットフォームに変身します。 Ten slotte transformeert het zichzelf in een rekruteringsplatform dat bekend staat als C3 Convertase. Por fim, transforma-se em uma plataforma de recrutamento conhecida como C3 Convertase.​

This platform is an expert at activating more C3 proteins that start the whole cycle anew.​ |||||||||||||||von Neuem Esta plataforma es experta en activar más proteínas C3 que inician de nuevo todo el ciclo.

An amplification loop begins.​ |Verstärkungsschleife|Verstärkungsschleife| |増幅|| Comienza un bucle de amplificación.

Soon, thousands of proteins cover the bacteria.​

For the bacteria, this is very bad.​

It can cripple the bacteria and make them helpless, or slow them down.​ ||削弱|||||||||| ||lähmen|||||||||| ||無力にする|||||||||| ||tàn phế|||||||||| Puede paralizar las bacterias y dejarlas indefensas, o ralentizarlas. Pode paralisar as bactérias e torná-las indefesas ou retardá-las.

Imagine being covered by thousands of flies.​ Imagina que te cubren miles de moscas.

But, there's more.​

Do you remember the other part of C3—the C3a protein?​

C3a is like a distress beacon.​ ||||||求救信号 |||||Notrufsignal|Notrufsignal ||||||遭難信号 C3a ist wie ein Notsignal. El C3a es como una baliza de socorro. C3a é como um farol de socorro.

Thousands of them flood away from the site of battle screaming for attention.​ ||||||||||um Aufmerksamkeit schreiend|| Miles de ellos se alejan del lugar de la batalla gritando para llamar la atención. Milhares deles saem do local da batalha gritando por atenção.

Passive immune cells notice the C3a proteins,​

and awaken from their slumber to follow the protein tracks to the site of infection.​ |erwachen|||Schlummer|||||||||| ||||眠りから目覚める|||||||||| e despertam de seu sono para seguir os rastros de proteínas até o local da infecção.

The more alarm proteins they encounter, the more aggressive they get.​ ||Alarmproteine||||||||

This way, complement guides reinforcements exactly to the place where they're needed the most.​ ||||增援部队||||||||| |||führt|Verstärkungen||||||||| ||||tiếp viện||||||||| De este modo, el complemento guía los refuerzos exactamente al lugar donde más se necesitan. Desta forma, o complemento orienta os reforços exatamente para o local onde são mais necessários.

So far, the complement has slowed down the invaders and called for help.​ ||||||||入侵者||||

Now, it's beginning to actively help to kill the enemy.​ ||||aktiv|||||

The first immune cells to arrive at the battlefield are ​ ​ phagocytes​ .​ ||||||||||吞噬细胞 ||||||||||Phagozyten ||||||||||食細胞 De eerste immuuncellen die op het slagveld arriveren, zijn fagocyten.

Which means, cells that swallow you whole, trap you in a tiny prison, and then kill you with acid.​ |||||||困住||||||||||| ||||||||||||Gefängniszelle||||||Säure Es decir, celdas que te tragan entero, te atrapan en una diminuta prisión y luego te matan con ácido. つまり、あなたを丸ごと呑み込み、小さな牢獄に閉じ込め、そして酸であなたを殺す細胞ということです。 O que significa que células que engolem você inteiro, prendem você em uma pequena prisão e depois o matam com ácido. Это означает, что клетки, которые проглатывают вас целиком, заключают в крошечную тюрьму, а затем убивают кислотой.

But, to swallow an enemy, they need to grab it first.​ しかし、敵を飲み込むためには、まずそれを捕まえる必要があります。

Which is not easy because bacteria prefer not to be grabbed and are sort-of slippery.​ ||||||||||抓住||||| ||||||||||gepackt||||| Lo cual no es fácil porque las bacterias prefieren que no las agarren y son algo escurridizas. 細菌は掴まれたくないし、滑りやすいので、それが簡単なことではありません。

But now, the complement that has anchored itself to the bacteria​ ||||||neo đậu|||| ||||||verankert|||| ||||||固定された|||| Pero ahora, el complemento que se ha anclado a la bacteria

acts as a sort-of glue that makes it easy for the immune cells to catch their victims.​ wirkt|||||Klebstoff||||||||||fangen|| |||||||||||||||||標的

But it gets even better.​ Pero aún hay más.

Imagine being covered in flies again.​ Now, imagine them turning into wasps.​ |||||||||||Wespen |||||||||変わる||スズメバチ Imagina que vuelves a estar cubierto de moscas. Ahora, imagina que se convierten en avispas. Another cascade is about to begin.​

On the surface of a bacteria, the C3 recruitment platform changes its shape again​ ||||||||Rekrutierung||||| ||||||||リクルートメント|||||

and begins to recruit new proteins.​ |||anwerben|| |||新たなタンパク質を募集し始める||

Together, they begin the construction of a bigger structure: a Membrane Attack Complex.​ ||||Bau||||||||

Piece-by-piece, new proteins shaped like long spears anchor themselves deep into the bacteria's membranes,​ ||||||||长矛||||||| ||||||||Speere|verankern sich|||||Bakterienmembranen| ||||||||槍のような|固定する|||||細菌の| Peça por peça, novas proteínas em forma de lanças longas ancoram-se profundamente nas membranas das bactérias,

until they rip a hole into them that can't be closed again.​ ||||||||||geschlossen werden| até que eles abrem um buraco neles que não pode ser fechado novamente.

Fluids rush into the bacteria and their insides spill out.​ Flüssigkeiten|||||||Inneres|auslaufen| |流れ込む|||||||| Los fluidos se precipitan dentro de las bacterias y sus entrañas se derraman. 液体が細菌に流れ込み、内部が流れ出す。 Os fluidos correm para as bactérias e seu interior se espalha. Жидкости устремляются к бактериям, и их внутренности выплескиваются наружу.

They bleed to death.​ Sie|verbluten|| |出血する|| Se desangran hasta morir. 彼らは出血死する。

The remaining bacteria are maimed and distracted by the complement,​ |verbleibend|||verstümmelt und abgelenkt||abgelenkt||| ||||傷つけられた||||| Las bacterias restantes son mutiladas y distraídas por el complemento. 残りの細菌は補体によって傷つき、気を散らされる。

and quickly taken care of by the arriving immune cells.​ |||||||ankommenden|| y rápidamente se encargan las células inmunitarias que llegan. e rapidamente atendidos pelas células imunes que chegam. и быстро лечится прибывающими иммунными клетками.

The invasion has been nipped in the bud before it had the opportunity to become dangerous.​ ||||扼杀|||萌芽阶段|||||||| ||||im Keim erstickt|||Keim|||||||| ||||摘み取られた||||||||||| La invasión ha sido cortada de raíz antes de que tuviera la oportunidad de volverse peligrosa. A invasão foi cortada pela raiz antes de ter a oportunidade de se tornar perigosa. Вторжение было пресечено в зародыше, прежде чем оно успело стать опасным.

You probably didn't even notice it.​ Probablemente ni siquiera te diste cuenta.

But while bacteria are not happy about complement,​ Но пока бактерии не радуются дополнению.

the enemies it might be the most useful against are actually viruses.​ die|Feinde|||||||||| die Feinde, gegen die es möglicherweise am nützlichsten ist, sind tatsächlich Viren.​ los enemigos contra los que podría ser más útil son en realidad los virus. Враги, против которых он может быть наиболее полезен, на самом деле являются вирусами.

Viruses have one problem: they need to travel from cell to cell.​ Viren haben ein Problem: Sie müssen von Zelle zu Zelle reisen.​ Los virus tienen un problema: necesitan viajar de célula a célula.

Outside of cells, they're basically hoping to randomly bump against a cell to infect by pure chance.​ |||||hoffen|||stoßen gegen||||||durch reinen Zufall|reiner Zufall| ||||||||ぶつかる|||||||| Außerhalb von Zellen hoffen sie im Grunde genommen darauf, durch puren Zufall gegen eine Zelle zu stoßen, um sie zu infizieren.​ Fora das células, eles basicamente esperam colidir aleatoriamente com uma célula para infectar por puro acaso.

Here, they're completely defenseless.​ |||在这里,他们完全无助。 |||Hier sind sie völlig wehrlos. |||無防備な |||vô defenseless

And here, complement is able to intercept and cripple them,​ ||||||拦截||| ||||||abfangen||| ||||||ngăn chặn||| E aqui, o complemento é capaz de interceptá-los e inutilizá-los,​

so they become harmless and guide the immune system to devour them.​ ||||||||||吞噬| |||harmlos||leiten|||||| ||||||||||tiêu diệt|

Without complement, virus infections would be a lot more deadly.​ |||Infektionen|||||| Sin el complemento, las infecciones víricas serían mucho más mortales.

But wait, if we have such an effective weapon, why do we ever get sick?​ Pero, si disponemos de un arma tan eficaz, ¿por qué enfermamos?

The problem is that in a war, both sides adapt.​ ||||||||Seiten|anpassen El problema es que en una guerra, ambos bandos se adaptan.

For example, when the ​ ​ vaccinia virus​ infects a cell,​ ||||痘苗病毒|||| ||||Vaccinia-Virus|||| ||||ワクシニアウイルス|||| ||||virus đậu mùa|||| Por ejemplo, cuando el virus vaccinia infecta una célula. Als het vacciniavirus bijvoorbeeld een cel infecteert, Por exemplo, quando o vírus vaccinia infecta uma célula,

it forces it to produce a protein that shuts complement activation down.​ ||||||||||激活补体| ||||produzieren||||schaltet ab||Aktivierung des Komplements| ||||||||抑制する||| le obliga a producir una proteína que cierra la activación del complemento. força-o a produzir uma proteína que desliga a ativação do complemento. он заставляет его вырабатывать белок, который блокирует активацию комплемента.

This way, the virus creates safe zones around the cells it infects.​ ||||||Zonen||||| De este modo, el virus crea zonas seguras alrededor de las células que infecta.

When it kills them, and tries to infect more, it has a higher chance of being successful.​ |||||versucht|||||||||||

Or some bacteria, for example, can grab certain molecules from the blood that keep the complement system calm​ |||||||||||||||||ruhig halten Oder manche Bakterien können beispielsweise bestimmte Moleküle aus dem Blut erfassen, die das Komplementsystem beruhigen und sich unsichtbar machen. O algunas bacterias, por ejemplo, pueden captar ciertas moléculas de la sangre que mantienen en calma el sistema del complemento

and make themselves invisible.​ Das Komplementsystem, obwohl äußerst wichtig,

So the complement system, while being extremely important,​ ||||während||| und machen sich unsichtbar.

is only one player in the complex and beautiful organization that is our immune system.​

A beautiful example of how many mindless things can do smart things together.​ ||||||||||intelligent|| Un bello ejemplo de cómo muchas cosas sin sentido pueden hacer cosas inteligentes juntas. Um belo exemplo de quantas coisas irracionais podem fazer coisas inteligentes juntas.

This video was sponsored by ​ ​ you​ .​

Without your direct support, this channel would not exist.​ ||direkte||||||

And it's hard to overstate how grateful we are for that.​ ||||夸大|||||| ||||übertreiben||dankbar|||| Y es difícil exagerar lo agradecidos que estamos por ello. E é difícil exagerar o quanto somos gratos por isso.

In 2019, an average kurzgesagt video took at least 1200 hours to produce.​

We need months to research and write our scripts, clear them with experts,​ ||||||||剧本|||| ||||||||Drehbücher|||| |||||||||確認する||| Necesitamos meses para investigar y escribir nuestros guiones, aclararlos con expertos. 私たちは、スクリプトを研究し執筆し、専門家と進め方を詰めるのに数ヶ月かかります。

illustrate and animate every scene from scratch, and to compose original music.​ ||||||从头开始|||创作|| |||||||||komponieren|| |||||||||作曲する|| ilustrar y animar cada escena desde cero, y componer música original. すべてのシーンをゼロから描画しアニメーション化し、オリジナルの音楽を作曲するのにも時間がかかります。

This is only possible through a combination of sponsorships,​ ||||||||赞助合作 ||||||Kombination||Sponsoring ||||||組み合わせ||スポンサーシップによって これはスポンサーシップの組み合わせによってのみ可能です。

your support on Patreon, and selling merch​ |||||Verkauf von Merch|

like this poster and postcards we made about The Complement System.​ ||Plakat||Postkarten|||||| ||||ポストカード||||||

If you, yourself, want to support us,​

you can do so by watching, becoming a Patreon, and maybe getting a personal bird.​

Or, by getting one of our calendars or posters.​ ||||||Kalender oder Poster|| ||||||カレンダー||

The purpose of kurzgesagt is to make the best videos we can​

and to make science more approachable.​ |||||zugänglicher |||||親しみやすい y hacer la ciencia más accesible.

Thank you so much for making this possible.​

​​