The left atrium and the left ventricle.

So blood would flow from the left ventricle, into a place it shouldn't be going, the right ventricle.

So this is the right ventricle, down here.

And then it goes into the right ventricle.

So now the journey starts with the left ventricle.

Blood flows from the right atrium to the right ventricle, then it goes to the lungs and from the left atrium to the left ventricle.

So this is chamber number three. And then the left ventricle.

At the same moment blood is going from the right atrium to the right ventricle, blood is actually also going from the left atrium to the left ventricle.

And the second one is relying on the left ventricle as the pump.

We're gonna actually follow the path of blood after it leaves the right ventricle.

All these different organs and tissues are gonna be getting blood from the left ventricle.

Let's start with blood going from the right atrium, this way into the right ventricle.

You have simultaneously two chambers that are full of blood, the right and left ventricle.

So we've gone from the right ventricle around to the lungs, back again into the left atrium.

And once the blood is in right atrium, it's going to head down into the right ventricle.

Let's start by labeling our heart, at the top, blood is coming into the right atrium, going to the right ventricle, it goes off to the lungs, comes back into the left atrium and then the left ventricle.

On the other side you have the mitral valve, which separates the left atrium from the left ventricle.

And it goes down into, you can probably guess how this one is called, is our left ventricle.

From the body... to the right auricle... to the right ventricle... and out the pulmonary arteries to the lungs.

We're gonna start our journey here at the right ventricle. So what's the first thing that kind of comes across?

In the new cycle you have a bit of blood that's going from the right atrium to the right ventricle.

The answer is no, because what happens is that as blood is moving down from the atrium to the right ventricle,

Let's say that by accident our ventricle was just too strong, too powerful, let's say it broke one of these cords.

In the middle, you can see that little structure squeezing out, that's the left ventricle, pushing blood out through the aortic valve.

Well, blood leaves the right ventricle, goes through a valve and after, on the other side you've got, this area right here.

Now, to start the journey, it's gonna have to out of the left ventricle and into the largest artery of the body.

And the Arotic valve is going to be what divides the left ventricle from this giant vessel that we talked about earlier.

And the blood goes down into the right ventricle. And then, on the other side I'm going to label the last two chambers.

Let me start there. For the systemic circulation, I'm gonna start in the left ventricle and it's gonna go round to the body.

Carbon dioxide is exhaled... and oxygenated blood continues passing through the veins... into the left auricle... through the left ventricle, passing out again.

So just like before where we went from the right atrium to the right vertricle, now we're going from the left atrium to the left ventricle.

Let's say it broke this one right here. That's because our ventricle was just forcing too much blood back and it just snapped the cord. What would happen?

And then we put a lead, which is a wire, in the right ventricle inside the heart, which does the electrogram, which is the signal voltage from inside the heart.

It goes around the ventricle and, as I showed you in the beginning, also around the atrium. It goes all the way up and covers both the left and right side.

And it's job is of course to make sure the blood does not go from the left ventricle back to the left atrium by accident. Wants to make sure there is forward flows.

But now remember that blood is constantly moving through the heart, so in a previous cycle you actually had some blood that's coming back from the lungs and that's what's dumping into the left ventricle.

And actually it stop there because of my arrows, but you can actually see now deoxygenated blood kind of goes from the right ventricle, through the pulmonary trunk, through the arteries and into the left and right lung.

Now when you look at this picture you could say, well, okay, I guess you can see all the different tissues are getting the blood, basically sounds like everything is coming from the oxygenated blood, coming out of the left ventricle.