Respiratory System

6. muscles between the ribs which contract to breathe in
8. the tube into which the trachea branches, carrying air
9. the movement of air in and out of the lungs
12. to breathe in
13. a large sheet of muscle that separates the lungs from the abdominal cavity

1. an air sac in the lungs, where gas exchange occurs
2. the curved bones attached to vertebral column and supporting the lateral walls of the thorax
3. muscular movements which cause air to move into and out of the lungs
4. the tube that carries air from the nose and mouth down to the lungs
5. strong, slippery membranes which surround each lung
7. to breathe out
10. the ribs and upper backbone, and the organs found in the chest
11. the small tubes into which the bronchi branch