Nurb.

[humming]

The nerves in those guys.

Let me guess, the Pinky Gang?

(SOBBING) They've got my Mommy.

[blowing nose]

[gasps]

What?

Your Mommy!

Those knuckle-headed jerks!

This has gone too far.

Now it's personal.

It's Mommy-saving time.

Read me that note again.

"Dear, Little Nurb -- that's what she calls me --

the Pinky Gang has taken me to the final chamber."

And that's it.

That's all she had time to write before they took her away.

Hmm, sounds like a riddle to me.

We just have to figure out what it means.

Oh, I'm out of breath.

And my heart's thumping like a runaway train.

That's because your body's working hard,

which means your heart and lungs have to work harder to get

oxygen through your body.

[gasps]

Wait, that's the answer, the heart.

Isn't the answer always in our hearts?

Well, yes.

But I meant the answer to the riddle.

I think they've taken her to the chambers of the heart.

Ah, yes.

Exactly as I suspected.

They may have the head start.

But we have the advantage.

We know the circulatory system.

We do?

We're going to follow this vein directly to the heart.

Thank you kind river for taking us on this noble quest.

Nurb, it's blood.

That's its job.

Your veins carry blood to the heart.

And your arteries carry blood away from the heart.

Away from my heart?

Is that safe?

It's not just safe, it's necessary.

You need blood everywhere, from the top

of your head to your toes.

And arteries and veins called blood vessels

are how the blood gets there and back again.

But why?

What do my toes need blood for?

Your body is made of tiny cells that all

need oxygen. It's your blood's job

to bring the oxygen to every part of your body,

including your toes.

So how does this oxygen get in the blood?

The lungs bring oxygen into the body when you breath.

From there, it has to find its way

to every other part of your body,

and the blood is its delivery service.

The heart pumps blood to the lungs to pick up oxygen

then pumps the oxygenated blood out to the rest of the body.

After the blood has delivered all the oxygen,

it picks up carbon dioxide, a waste product.

Then the blood goes back to the lungs

to drop off the carbon dioxide and pick up more oxygen.

And the whole process begins again.

The circle of life.

Uh, Chloe?

How long are we going to be on this boat?

(SINGING) There's no earthly way of knowing.

The oxygen just keeps on flowing.

And the eyeball keep on rowing.

And they show no sign of slowing.

Oh!

Oh, Chloe!

Make it stop!

OK, we're here.

Chloe, this heart is huge.

The human heart is only about the size of a fist.

But this is the heart of Bodylandia.

Now, the note says they have her in the final chamber.

If we follow the blood flow through the heart,

it will take us through the four chambers of the heart, the two

atria and two ventricles, and right to her.

Watch out Mommy stealers, here we come.

Uh, Nurb.

Blood is going that way.

Here we come.

We started in the right atrium where

the blood enters the heart.

From there we followed the blood through the tricuspid valve

into the right ventricle.

Valves keep blood flowing into the right direction.

Next, it took us through another valve, the pulmonary this time,

and through the pulmonary artery up to the lungs.

That's where the blood loaded up on oxygen.

We all left that place fully oxygenated,

exited through the pulmonary veins into the left atrium,

then, at last, through the mitral valve

and into the left ventricle.

The final chamber.

What's that noise?

Mommy!

Oh no, what have you done to her?

Jonathan Nervequith Nervington, you shush now.

I'm fine.

But you were stolen by the Pinky Gang.

How could you be fine?

Stolen?

I wasn't stolen, you silly little nurb.

I'm teaching my Monday morning yoga and meditation class.

What?

Didn't you read the note I left you?

[coughs]

"The Pinky Gang has taken me to the final chamber."

Turn it over.

Oh, [coughs] "for our Monday morning yoga and meditation

class."

But it's the Pinky Gang.

They're the bad guys.

Oh, they're not that bad, they just need to relax.

I'm teaching them how to find their centers.

I feel so focused.

So tranquil.

I never realized being evil was so stressful.

Why don't you join us?

When we're done, we can all leave together

with the oxygen-rich blood through the aorta.

(CHANTING) Circulatory, circulatory, circulatory.