Two of the valves I'm gonna name, I'm giving them new names, something slightly different from what we've been referring to them by. These are the atrioventricular valves.

And then you can see the inside of the heart.

This attempt was made from cell 212.

Is it your cell?

Keep your eye on the valves and we'll talk about them as the blood moves through.

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

The trunk?

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

The keys are in the trunk.

So let's get started in the upper part of the heart. The Right atrium, It's right there.

You charge another inmate to clean his cell.

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.

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

In the trunk.

It's in the trunk.

There's sort of illegal hustles, like you run a barbershop out of your cell.

So you've already learned that the valves got endocardium.

In the boot

Trinette throw me in a trunk? !

So I'm gonna just take some blue paint to indicate deoxygenated blood or blood without oxygen, I'm gonna paint in how it look.

You, open the trunk.

You pay everything in stamps. Those are the currency.

I love the trunk.

Doctor, your problem is so little faith.

He's telling the truth, officer. Get out. Open up the trunk.

Anything in the baggage compartment?

And make sure it's got a big trunk.

Can you open your trunk, sir?

Open your trunk.

Open the boot!

Doug's in the trunk.

Open the trunk.

Back in the late 19th century, the only source of heat in most homes was a big fireplace in the kitchen that was used for cooking and heating.

But I've got his ppocket bike in the trunk.

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

We're gonna open the trunk.

In the trunk or the glove compartment?

Did you find anything in the trunk of this one?

It's in the trunk.

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.

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

Just to orientate us this is the tricuspid (T) and this is our mitral (M).

Tom looked in the trunk.

And the girl in the trunk?

The girl in the trunk has nothing to do with it.