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  • I really like this picture that I found. It actually

    わかりやすい心臓の図を見つけました。

  • shows you really neatly where the heart sits in our body

    体のどこにあるかよく分かります。

  • so you can see the heart is surrounded, on both sides, by ribs, right?

    心臓は肋骨に囲まれています。

  • And in fact, I didn't draw it in yet, but let me show you where the

    そしてその横には肺があります。

  • lungs would be. This is the right lung

    これが右、こちらが左の肺です。

  • and on this side you'd have the left lung. So this is where

    心臓はこのように肺の間にあります。

  • your heart sits: between two lungs. And I'm saying

    左右はこの人から見た右と左です。

  • left and right from the perspective of the the person who owns this

    こちらから見ると反対になります。

  • heart. So this is their left and right, which is the opposite

    このように心臓は肺と肺の間で、肋骨に守られています。

  • of us if we're looking at it. The heart is actually sitting between the two

    その下にはこんな風に、

  • lungs within this protective casing that

    とても大事な筋肉があります。

  • the ribs are basically there to keep all these important organs

    あまり注目されないし、運動するときにも意識されませんが、

  • safe. And then below them, so if you draw

    隔膜といいます。

  • this here. Or if I draw it, you can

    この隔膜と肋骨は1つの部屋を作っていて、

  • see now that below all this stuff is

    隔膜が床に、肋骨が壁と天井にあたります。

  • a really really important muscle. So this muscle

    中には肺と心臓が収まっています。

  • people don't talk about this muscle, or this is not the kind of muscle

    この部分を胸部といいます。

  • that you usually see people working on at the gym, but this muscle is called the diaphragm.

    では心臓はどんな働きをするのでしょう。

  • So your diaphragm muscle

    これは心臓の拡大図です。

  • and your ribs are enclosing a space, right? The diaphragm becomes the floor, and the ribs are kind of the

    これが右の肺、反対側には左の肺があります。

  • ceiling and the walls of this space.

    これが肋骨に囲まれているのですが、割愛します。

  • And if you look at the contents of this space, you'd have your lung

    書き入れると心臓が見えにくいからです。

  • and you'd have your heart. So, this entire space then

    さて、心臓の働きについて考えるとき、細胞を思い浮かべるとわかりやすい。

  • is called your thorax.

    細胞をここに描きましょう。

  • So what exactly does the heart do? Let's actually make a little bit of

    つま先の細胞ということにしましょう。

  • space now, and bring up a

    細胞が生きていくために、この近くには血管があります。

  • zoomed in version of the heart.

    体のどこの細胞でも、近くには血管があります。

  • Let me start by orienting you to the heart. This is our right lung

    このつま先の細胞が生き続けるためには

  • and on the other side we have our left lung. And all this would be

    酸素や、栄養などが必要です。

  • inside of the rib cage, but I'm not going to draw that now, because that would

    細胞が生き続けるには、こういったものが必要です。

  • make it harder to see the heart itself. So to think

    その一方で外に出すものもあります。

  • about exactly what the heart does, I think one, kind of neat way to do it is

    私達の体と同じく、余分なものを排出するのです。

  • to actually imagine that you're a cell. So put yourself in the perspective

    細胞の老廃物といえば二酸化炭素です。

  • of a cell, and let's say you're a cell hanging out

    今、血液が流れていないと仮定します。

  • over here. This is you. And you can

    近くにある血管にも血流はありません。

  • think about any part of the body that you could be. Let's say a little

    つま先の細胞が老廃物を排出すると、

  • toe cell. So let's say you're a toe cell

    こんな風に溜まっていきます。

  • and your job, of course, is to live and be happy,and you've got

    血液が流れていないからです。

  • near by, a little blood vessel. And in fact, every cell in our body

    細胞の周りにも溜まっていきます。

  • has a little blood vessel that's near by. And this toe cell

    そして老廃物で覆われてしまうのです。

  • is just trying to make a living. And toe

    酸素も栄養も運ばれてきません。

  • cells need certain things, right? They need, for example, let's say oxygen.

    一分もすれば、ここは暮らしにくいなと細胞は思うでしょう。

  • I'll write it in white so it's very clear. They need oxygen

    悲しい気持ちになります。

  • and they need nutrients, right?

    こんな状態が続くと細胞は死んでしまいます。

  • So cells need certain things to live and be happy.

    細胞には、足であれ皮膚であれ、どの細胞も

  • And on the flip-side, they also make waste. They're in

    生きている限り、血流が必要です。

  • a sense just like us, they make waste. And that waste could be

    血が流れていれば状況は違います。

  • all sorts of things, and one that kind of jumps to mind is

    このような老廃物は流されていってしまいます。

  • carbon dioxide (CO2). So carbon dioxide is waste

    ゴミが運ばれて、家が綺麗になるようなものです。

  • for this cell. So it's making some

    血液が流れれば、酸素や栄養も運ばれてきます。

  • waste and for the moment let's imagine that there's no blood flow.

    こうして細胞は気分良くなり、健康になるのです。

  • So, even though there's a blood vessel near by,

    体中の細胞をこんな状態にするには

  • really, no flow is happening, so I'll just write "no flow".

    体中の血液がうまく循環している事が大事です。

  • So as the little cell

    これがポイント1。

  • makes waste. That waste, let's draw a little ball right here,

    体中の血液は滞り無く循環していなければなりません。

  • it's going to start accumulating, you're going to start collecting more and more of it

    体中にある何兆個という細胞に血液を循環させるには

  • since the blood is not really flowing. And it might kind of

    強力なポンプが必要です。

  • end up getting all the way around our toe cell. So our toe cell is getting

    血液を吸い込んで、それを吐き出せるようなポンプです。

  • swamped, literally getting kind of covered by its own waste.

    それができるのが心臓であり、心臓の役目なのです。

  • And on the flip-side, is it getting oxygen or nutrients? No.

    血液を体中に送り出して循環させる。

  • It's not getting either of these things. So, before very

    これが心臓の働きの一つめです。

  • long, I would say within minutes, our toe cell

    1つめの働きが血液を送り出すこと。

  • is thinking, "Well this is not a very happy way to live!" this is

    体全体の流れを作り出します。

  • actually really very sad, this is awful. And if this continues

    体中にある細胞に血液を送り出すのです。

  • the toe cell would die. So, what a toe

    どのようにして血液が送り出されるのか、

  • cell needs, and what every cell needs, and that could be a finger cell or a

    この図を見ると分かります。

  • skin cell, or really any cell that's living, needs

    これが静脈です。

  • flow. Right? It needs this blood to be flowing nicely

    こちらが動脈。

  • and smoothly. And if there is flow

    血液は動脈を通ってこちらに流れます。

  • then you get a very different picture, right? If there's flow then all the sudden all the

    こちらの方からは2本の静脈に血液が流れます。

  • waste product is actually now lifted and taken away.

    その内の1本は上大静脈と呼ばれるものです。

  • It's flowing away, and it's a little bit like having

    ここからは見えませんが、

  • someone come by and pick up the trash, then you don't have trash all over the house.

    ここにはもう一本の静脈、下大静脈があります。

  • So then you have nice flow, and

    この2本の静脈が体中の血液を吸い込んで、

  • in return, oxygen and nutrients are delivered. So this stuff

    心臓に送り込んでいるのです。

  • gets delivered as well. So, all of the sudden the cell is going to be

    心臓が拍動によって押し出した血液は動脈に流れます。

  • very, very happy, and is going to be living just fine.

    この動脈を大動脈といいます。

  • So, really if you want all of the cells in your body to be living just fine

    血液はこのようにして心臓の力で循環しているのです。

  • like this cell here, you really want good flow throughout the

    心臓の働きは他にもあります。

  • body. And so this is really point number one. Is that you really

    ふたつ目は肺に血液を送り出すことです。

  • need, somehow, to have blood flow moving and pushing

    肺血流といいます。

  • blood constantly through the body. So,

    細胞は酸素を欲しがっていますね。

  • to do this for billions and billions of cells you would need a pretty powerful

    老廃物も出します。

  • pump, right? Something that's going to be able to pull

    血液の循環は大切なことですが、

  • in all the blood from the body, and then push it back out. And that's what the heart

    循環するだけでは老廃物を除去できず、酸素も供給されません。

  • is. I mean at its core, that's exactly what the heart is doing.

    細胞にとっては住みにくい。

  • It's an amazing pump, pushing blood, so that

    血液の循環と同時に酸素も必要です。二酸化炭素の除去も。

  • you have good blood flow. And so I'm

    ここで肺の登場です。

  • going to write that on the side as kind of job number one. These are the jobs of the heart.

    血液は大動脈に送り出される前に、肺に送られるのです。

  • So jobs, and number one, would be

    左の肺と右の肺に送り込まれ、

  • blood flow. And I'll write systemic

    右と左の肺から血液が戻ってきます。

  • flow. Systemic flow. And all

    そして心臓の収縮によって大動脈に送られるのです。

  • that systemic means is that I'm refering to the entire body. So systemic

    ここで血液はいったん血管を出て肺の中を循環する。

  • when I say that word, I just mean the entire body. All the cells

    これを肺血流といいます。

  • in the body. Now, exactly how that happens actually

    さて、最後にこのグニャグニャ曲がった血管です。

  • you can see on this picture. So, here you have a giant

    心臓全体を覆っています。

  • vein, this is a vein, and you have an artery.

    これは何でしょうか。

  • This is an artery.

    青いのが静脈、赤いのが動脈です。

  • And blood is actually going through the artery, that way.

    これは体全体の循環なのか、肺血流なのか、あるいは別物か。

  • And it's actually coming into two veins, the one

    これらの血管を冠状血管といいます。

  • at the top, this is called the superior, superior just kind of means

    先ほど動脈、静脈という言葉が出てきましたが、

  • at the top. Superior vena cava. That's the

    ここにある血管を総称して冠状血管といいます。

  • name of the vein. And at the bottom here, you can't see it because

    この環状血管は心臓の筋肉に酸素を供給しています。

  • it's on the other side of the heart, but there's another vein called the inferior vena cava.

    心臓は何万個という細胞からできています。

  • And these two veins, this is also a vein,

    この細胞も、つま先の細胞と同様

  • these two veins are actually dragging blood in from all over the body,

    酸素や栄養素を必要とし、老廃物も出します。

  • into the heart.

    ですからそれを供給する血管が必要なのです。

  • And then, when the heart is ready to pump it back out, it goes into this

    これが冠状血管の役目です。

  • artery, and the name of it is the aorta.

    心臓に酸素や栄養素を供給しているのです。

  • So if you've heard of the aorta, this is the artery that people

    心臓の働きを助けているのなら、

  • are talking about. So this is how blood comes and gets pumped

    これは体全体の循環に繋がっているのでしょうか。

  • around. But this isn't actually the only job of the heart. The job,

    肺の血流なのでしょうか。

  • the second job of the heart, is actually

    細胞に酸素を供給するという点からは

  • also in this picture, and it's called pulmonary flow.

    冠状血管は体全体の循環だと言えます。

  • Pulmonary flow. So, what does that

  • mean? Well, we know that cells are expecting

  • oxygen, right? We know this. And that they have a lot of carbon dioxide

  • waste. Well, it's good to move things around. It's good

  • to move blood around. But if you actually never got rid of that carbon dioxide

  • or brought in new oxygen, then a cell is not going to be very happy either.

  • I mean, you can have blood flow, but at some point it's also going to want some oxygen.

  • And it's going to want to get rid of that carbon dioxide. So, that's where the

  • lungs come in. So what happens is that the heart, before

  • sending blood out the aorta, before just dishing it out back into the body,

  • it actually sends the blood over to the

  • lungs. And it goes over to the left lung, and over to the right lung.

  • And the blood comes back from the right lung

  • and the left lung, and gets pushed back into

  • the heart, and then gets squeezed through the aorta. So there's this

  • actual extra little step here, where blood is going to

  • and from the lungs, and that's the pulmonary flow.

  • So the final thing you'll notice, if you look at this picture it's hard not to notice,

  • is that there are these, kind of wriggly looking little

  • blood vessels all over the heart. And what are these

  • exactly? I mean, you've got red ones, and blue ones, and

  • the blue ones are the veins, and the red ones are the arteries

  • but are they part of the systemic flow, or pulmonary flow, or something else?

  • Well, these vessels, all of them,

  • together are called coronary vessels.

  • And so specifically you might hear about

  • a coronary artery, or a coronary vein, but together you can call them

  • coronary blood vessels. I'll add the word blood here. So these

  • coronary blood vessels are actually serving the heart muscle

  • itself. I mean remember, the heart

  • is made up of thousands and thousands, actually tens of thousands of cells

  • and those cells, just like our toe cell that we drew,

  • they also need oxygen, nutrients, and have waste.

  • So, those cells are going to need blood vessels supplying

  • them as well. So, that's what the coronary blood vessels are. They're literally

  • the blood vessels that go to and serve

  • the heart. So these are the ones that serve the heart.

  • Now, if they're serving the heart muscles

  • and the heart cells, then, think about it, would they fit under

  • the systemic flow, or pulmonary flow? Well if the

  • main job is to serve the needs of cells, then

  • the coronary vessels fall under the systemic flow.

I really like this picture that I found. It actually

わかりやすい心臓の図を見つけました。

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