KidsHealth presents "How the Body Works,"

with Chloe and the Nurb.

And then, the gall bladder stands up and finishes my joke.

I mean, the gall of that guy.

Hold that thought, Nurb.

What's this?

Hmm, 5th Annual Bodylandia Lung Race.

The duo that gets into and then out of the lungs

first wins a prize.

A prize?

A prize, Chloe.

Oh my dear heavens, a prize!

Hmm, if the time on this poster is right,

the race is about to start any minute.

Yikes!

We better get into our running outfits.

The Nurb is always ready for a race.

Chloe is too.

To the racetrack.

[MARIO CART THEME MUSIC]

Phew, made it in the nick of time.

They're about to start.

[SNEEZE]

And they're off.

The kidneys are in the lead, followed

by the eyeballs and the ears.

Chloe and the Nurb are in dead last.

Chloe, let's pick up the pace, shall we?

This isn't working.

And I'm breathing really hard.

You're breathing hard, because your body

needs more oxygen. Oxygen is in the air we breathe.

When you're breathing hard, your lungs can take in more oxygen,

and your heart is beating faster to get that oxygen

all around your body.

In we go!

Do you know where we're going?

Of course!

Into the respiratory system, and more specifically, the lungs.

Ugh, this is gross, Nurb.

There are boogers everywhere.

Let's get out of here, Chloe.

When you inhale, hair comes into your nose or mouth

and then down your windpipe, also called the trachea.

At the end of the trachea are two large tubes

called the bronchi.

They lead to two large organs, responsible for breathing,

called lungs.

One bronchus goes to the left lung, and the other one,

to the right.

The lungs inhale air with the help from your chest muscles

and diaphragm, a dome-shaped muscle under the lungs.

As you breathe in, your diaphragm

contracts and flattens out.

This allows it to move down, so your lungs

have more room to expand as they fill up with air.

So when you exhale, everything happens in reverse,

and the air goes out the way it came in?

Exactly.

Here we come!

This is the lungs?

Nurb, it's just another set of tubes.

The lungs have tons of these smaller and smaller

sized tubes, called bronchioles, which

can be as small as the thickness of a hair.

The end should be right after the next one.

Here we come!

Nurb, where are we?

The alveoli.

Fancy word!

This is where the magic happens, where

oxygen from the air we breathe gets absorbed into the blood.

Alveoli are tiny air sacs at the end of each bronchial.

There are about 600 million alveoli in the lungs.

Each has a mesh-like covering of very small blood vessels called

capillaries.

Oxygen travels into the blood through the alveoli

into the tiny capillaries that surround them.

Fantastic

All right.

We've got a race to win.

But before we go, I should explain

the process of exhaling.

The air you breathe in is different than the air

you breathe out.

The most important gas in the air

is oxygen. Every one of your body's cells

needs oxygen to stay alive.

Deep inside the lungs, your body takes oxygen from the air

and delivers it to the bloodstream.

Then your heart can pump oxygen-rich blood

all around the body.

Then, the process operates in reverse,

letting your body get rid of a gas called

carbon dioxide, which is waste gas the body doesn't need.

Carbon dioxide is carried by the bloodstream through the lungs,

then the lungs exhale it out of the body.

Nurb, we're falling further and further behind in the race.

No worries!

I'll kick it into Nurb hyper drive!

We're doing it!

We're winning!

We're Nurbing now!

We did it!

We won!

The crowd goes wild!

Why is everyone so quiet?

Uh, Nurb, we won the race like 45 minutes ago.

Oh.

[MUSIC PLAYING]