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 CO 2 exits the blood. stream and enters the lungs, you breathe out, this how your body gets rid of CO 2.  When you hold your breath, CO 2 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.