Chapter 4 Lesson 2

The Respiratory SystemBy: CeCe and Caitlin

Parts of the respiratory system Mucus: is a sticky, thick, fluid that traps dust,

germs, and other harmful substances. Trachea: is a tube that carries air from the

Larynx. Larynx : houses your vocal cords Bronchioles : are the tubes that branch from

your bronchi. They eventually end in air sacs. Air sacs : are where oxygen enters the blood

and carbon dioxide exits the blood. Cilia : are tiny hair-like structures that clean air

by waving rapidly.

respiratory and circulatory systems work together All multicellular organisms need oxygen. They need oxygen to release energy from

glucose that cells need. Air sacs and capillaries have an important

job : they supply the blood with oxygen. They do this by transporting carbon dioxide

into the air sacs, when that happens oxygen takes its place in the blood stream.

Getting rid of carbon dioxide When CO2 exits the blood. stream and enters

the lungs, you breathe out, this how your body gets rid of CO2.

When you hold your breath, CO2 builds up in your blood.

your brain senses this and sends a message to the rib muscles and the diaphragm telling them to breathe.

In this way, several systems in your body work together to make sure your cells get oxygen.

How you breathe When you inhale, your diaphragm

contracts and moves down, making more space in your chest.

Your rib muscles may also pull your rib cage up and out, making still more space.

Air quickly rushes into the lungs and takes up these new spaces.

When your diaphragm and rib muscles relax, they push air out of the lungs.