1. The set of organs that allows a person to breathe and exchange oxygen and carbon dioxide throughout the body.

2.  Inhale - (breathe in) oxygen from the outside enters and moves to the lungs.  Exhale – (breathe out) carbon dioxide forces from your lungs back to the environment.

3. Structures of the Respiratory System Nose Inhale oxygen cilia – small hairs -filter dust and dirt particles from entering your throat mucus membranes warm and moisten the air Mouth Inhale oxygen No filtering, warming, or moistening air.

4. Pharynx (throat)  behind the nose and mouth  pathway for air and food  epiglottis -flap of cartilage that closes over the trachea when swallowing to keep food from entering the trachea

5. Trachea (windpipe)  flexible tube (5 inches)  takes air to and from the bronchi and into the lungs  has several C-shaped cartilage rings that keep the trachea open Trachea Bronchi Larynx

6. Lungs (two) the largest organs in your body left side a little smaller then right, leaves room for your heart. protected by your rib cage Bronchi two large tubes bringing air to each lung.

7. Bronchioles smaller tubes that branch out from each bronchi, look like branches on a tree. Each is about the same thickness as a hair. About 30,000 in each lung

9. Alveoli At the end of each bronchiole is a special area that leads into clumps of teeny tiny air sacs There are about 600 million alveoli in your lungs Each alveoli has a mesh-like covering of very small blood vessels called capillaries.

10. Oxygen passes through the walls of the alveoli into the tiny capillaries that surround it and enter the blood stream Travelling in the opposite direction is carbon dioxide, which crosses from the blood in the capillaries into the air in the alveoli and is then breathed out.

11. Diaphragm a dome-shaped muscle below the lungs and aids in breathing

12. Inhalation  The diaphragm contracts (pushes down) and the rib cage rises  This expands the volume of the chest cavity and gives the lungs room to expand  Air rushes in and fills the lungs Exhalation  The diaphragm relaxes (pushes up) and the rib cage lowers This reduces the volume of the chest cavity and gives the lungs less space  Air is pushed out of the lungs.