Chapter 4 Lesson 2

1. Chapter 4 Lesson 2 The Respiratory System By: CeCe and Caitlin

2. 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.

3. 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.

4. 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.

5. 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.