in your body.

体の中でも、抜群に素晴らしい臓器です。

This is the human heart.

表面には心臓に繋がっている血管が見えます。

And it's shown with all the vessels on it.

心臓の働きはポンプに似ています。

And you can see the vessels coming into it and out of it.

まだ生まれていない、妊娠8週の胎児の時期から

But the heart, at its core, is a pump.

ずーっと死ぬまで、体に血液を送り続けるのです。

And this pump is why we call it the hardest working organ

この心臓を詳しく見られればいいのですが、

in our body.

外から見ることはできないので、

Because it starts pumping blood from the point where you're

内側が分かるように絵を描きました。

a little fetus, maybe about eight weeks old,

心臓の中をどのように血液が流れるか、

all the way until the point where you die.

この絵で見てみましょう。

And so this organ, I think, would

これは人の顔です。

be really cool to look at in a little bit more detail.

そしてこれが首、

But it's hard to do that looking just at the outside.

腕も描きます。

So what I did is I actually drew what

そして胸には心臓があります。

it might look like on the inside.

心臓の働きは体全体に血液を送り出し、

So let me actually just show you that now.

それをまた元の心臓に戻すことです。

And we'll follow the path of blood

血液がこちらから、そしてこちらからも流れてきます。

through the heart using this diagram.

頭の方からも流れてきます。

Let me start with a little picture in the corner.

こうした血液は一本の静脈に集まり、

So let's say we have a person here.

心臓の上の部分に流れていきます。

And this is their face, and this is their neck.

血液は足の方からも流れてきて、

I'm going to draw their arms.

別のところから心臓に流れます。

And they have, in the middle of their chest, their heart.

こうして血液は体中から心臓に戻ってきます。

And so the whole goal is to make sure

血液を心臓へ運ぶ血管を静脈といいます。

that blood from all parts of their body,

このように心臓に血液が送られてくれば、

including their legs, can make its way back

これをどこかに押し出さなければなりません。

to the heart, first of all, and then

押し出された血液が通るのが大動脈です。

get pumped back out to the body.

大動脈は弓のような形。大動脈弓といいます。

So blood is going to come up from this arm, let's say,

ここから腕や頭の方に血液が流れ、

and dump into there.

ずっと下がってこの辺りで分岐します。

And the same on this side.

簡単に描きましたが、動脈と静脈は

And it's going to come from their head.

このようにほぼ並んでいることが分かると思います。

And all three sources, the two arms and the head,

動脈からは血液が体の末端に向かって流れます。

are going to come together into one big vein.

わかりやすいように、これをAとします。

And that's going to be dumping into the top of the heart.

さてこちらの図です。

And then separately, you've got veins

血液はこことここから入ってきて、

from the legs meeting up with veins from the belly,

ここで1つになります。右心房です。

coming into another opening into the heart.

血液は上大静脈から運ばれてくるのです。

So that's how the blood gets back to the heart.

これは体中の血液を心臓に送りますから静脈です。

And any time I mention the word vein,

こちらは下大動脈です。

I just want you to make sure you think

血液はこの2つの血管から流れてきます。

of blood going towards the heart.

右心房に集まった血液は右心室に送られます。

Now if blood is going towards the heart,

これが右心室。

then after the blood is pumped by the heart,

心臓の2つ目の部屋です。

it's going to have to go out to the heart.

血液は右心房から弁を通して流れてきます。

It's going to have to go away from the heart.

心臓にある弁は全部一方通行で、

So that's the aorta.

逆流することはありません。

And the aorta actually has a little arch, like that.

この弁を三尖弁といいます。

We call it the aortic arch.

小さい弁が3つでできているからです。

And it sends off one vessel to the arm, one vessel up

2つしか描いてありませんが。

this way, a vessel over this way.

右心室の血液はどこに行くのでしょう。

And then this arch kind of goes down, down, down

この血管を通って2つにわかれます。

and splits like that.

この弁を通るのです。肺動脈弁といいます。

So this is kind of a simplified version of it.

名前を見るとこの血液がどこに行くか分かりますね。

But you can see how there are definitely

肺です。ここに肺を描きましょう。

some parallels between how the veins and the arteries

これが左の肺、こちらが右です。

are set up.

この血管は何というでしょう。

And arteries, anytime I mention the word artery,

これが左肺動脈。

I want you to think of blood going away from the heart.

心臓からここを通って血液が送り出されます。

And an easy way to remember that is

こちらが右肺動脈。

that they both start with the letter A.

血液はこのように肺に流れて行きます。

So going to our big diagram now.

肺は胸にあり、その奥に心臓があります。

We can see that blood coming in this way and blood coming

この血管は青ですね。

in this way is ending up at the same spot.

どうしてでしょう。

It's going to end up at the-- actually,

青い血管には酸素があまりありません。

maybe I'll draw it here-- is ending up at the right atrium.

ここに酸素が供給されます。

That's just the name of the chamber

青い血管には二酸化炭素が沢山あります。

that the blood ends up in.

体中から集まってくるので、

And it came into the right atrium from a giant vessel

老廃物が入っているのです。

up top called the superior vena cava.

肺ではこの老廃物が除去され、酸素が供給されます。

And this is a vein, of course, because it's

ですから、血管の色はここで青から赤になります。

bringing blood towards the heart.

肺の血液はここから心臓に戻ってきて、

And down here, the inferior vena cava.

ここに入ります。

So these are the two directions that blood

左心房といいます。

is going to be flowing.

右側と同じです。

And once blood is in the right atrium,

そして左心室に流れていくのです。

it's going to head down into the right ventricle.

右側と同じように、左心房から左心室に。

So this is the right ventricle, down here.

この弁は僧帽弁といいます。

This is the second chamber of the heart.

この弁も一方通行で逆流することはありません。

And it gets there by passing through a valve.

最後に通る弁は大動脈弁です。

And this valve, and all valves in the heart,

この弁を通過した血液は

are basically there to keep blood

こちらの太い血管に分かれていきます。

moving in the right direction.

太い血管は大動脈です。

So it doesn't go in the backwards direction.

血液は大動脈から体中に流れていきます。

So this valve is called the tricuspid valve.

このように、体にある血液は

And it's called that because it's basically

心臓の4つの部屋に流れ込みます。

got three little flaps.

最初の部屋が右心房、

That's why they call it tri.

次が右心室、

And I know you can only see two in my drawing,

それから肺に流れ、左心房に戻ります。

and that's just because my drawing is not perfect.

そして左心室へ。

And it's hard to show a flap coming out at you,

生きている間じゅう、心臓が鼓動する度に

but you can imagine it.

このプロセスが繰り返されるのです。

So blood goes into the right ventricle.

And where does it go next?

Well after that, it's going to go this way.

It's going to go into this vessel,

and it's going to split.

But before it goes there, it has to pass through another valve.

So this is a valve, right here, called the pulmonary valve.

And it gives you a clue as to where

things are going to go next.

Right?

Because the word pulmonary means lungs.

And so, if this is my lung, on this side,

this is my left lung.

And this is my right lung, on this side.

Then these vessels-- and I'll let

you try to guess what they would be called-- these vessels.

This would be my-- I want to make sure I get my right

and left straight.

This is my left pulmonary artery.

And I hesitated there just to make

sure you got that because it's taking blood away

from the heart.

And this is my right pulmonary artery.

So this is my right and left pulmonary artery.

And so blood goes, now, into my lungs.

These are the lungs that are kind of nestled

into my thorax, where my heart is sitting.

It goes into my lungs.

And remember, this blood is blue.

Why is it blue?

Well, it's blue because it doesn't have very much oxygen.

And so one thing that I need to pick up is oxygen.

And so that's one thing that the lungs

are going to help me pick up.

And I'm going to write O2 for oxygen.

And it's also blue.

And that reminds us that it's full of carbon dioxide.

It's full of waste because it's coming from the body.

And the body's made a lot of carbon dioxide

that it's trying to get rid of.

So in the lungs, you get rid of your carbon dioxide

and you pick up oxygen.

So that's why I switch, at this point,

from a blue-colored vessel to a red-colored vessel.

So now blood comes back in this way and this way and dumps

into this chamber.

So what is that?

This is our left atrium.

So just like our right atrium, we have one on the left.

And it goes down into-- and you can probably

guess what this one is called-- it's our left ventricle.

So just like before, where it went from the right atrium

to the right ventricle, now we're

going from the left atrium to the left ventricle.

And it passes through a valve here.

So this valve is called the mitral valve.

And its job is, of course, to make sure

that blood does not go from the left ventricle back

to the left atrium by accident.

It wants to make sure that there's forward flow.

And then the final valve-- I have

to find a nice spot to write it, maybe right here.

This final valve that it passes through

is called the aortic valve.

And the aortic valve is going to be

what divides the left ventricle from this giant vessel

that we talked about earlier.

And this is, of course, the aorta.

This is my aorta.

So now blood is going to go through the aorta

to the rest of the body.

So you can see how blood now flows from the body

into the four chambers.

First into the right atrium-- this is chamber number one.

And then it goes into the right ventricle.

This is chamber number two.

It goes to the lungs and then back out to the left atrium.

So this is chamber number three.

And then the left ventricle.

And this happens every moment of every day.

Every time you hear your heart beating,

this process is going on.