The New Childrens Encyclopedia

TAKE A BREATH

285

THE ROUTE IN

When you breathe in, air first travels

down your pharynx (throat), then your

larynx (voice box), before entering your

trachea (windpipe) to get to your lungs.

About 20 C-shaped rings of cartilage

hold the trachea open.

Nasal cavity

Making sounds, too

Breathing is also connected

with making sounds. Two

membranes, the vocal cords,

stretch across the larynx. When

you breathe out, air passes over

the vocal cords, making them

vibrate. Your lips and tongue

shape these sounds into speech.

The larynx links

the throat to the

trachea.

Interior of left lung showing

the branching arteries (red),

veins (blue), and airways

(bronchi, shown in gray).

 CILIA The trachea is lined

with millions of microhairs.

These are called cilia and they

beat with a wavelike motion

to propel mucus, microbes,

and dust up the trachea to be

coughed up.

The trachea

branches into two

tubes, or bronchi,

one for each lung.

We take a breath some 23,000 times

each day. Each breath results in a

constant flow of oxygen to the cells.

You cannot survive for long

without this supply.

The diaphragm separates the

chest cavity from the abdomen.

7

/^7 

THE HUMAN BODY

Muscles between the
ribs help to move
them up and out
as you breathe in.

Pharynx

The epiglottis moves over

the entrance to the larynx

when swallowing.

Heart