2. The Breathing Process An Explanation about the Lung Model

3. Breathing In Breathing in is called INHALING or INSPIRATION. When you inhale, you fill your lungs with air.

4. Breathing Out Breathing out is called EXHALING or EXPIRATION. When you exhale, you push air with more carbon dioxide out of the lungs.

5. Breathing Process Breathing is an involuntary process because we do not think about it when we do it. Breathing is important to keep us alive.

6. Breathing Body Parts The lungs are important and delicate organs. They are protected by a set of bones called rib cage. The rib cage forms the chest cavity where the lungs are found. There is a sheet of muscles at the lower part of the chest cavity called the diaphragm. The diaphragm separates the chest from the abdomen.

7. Pulling it down… When you pulled down the string tied to the rubber sheet, the space inside the bottle increased. This action represents the contraction and downward movement of your diaphragm.

8. Pulling it down … As the diaphragm moves down and the rib muscles contract, the chest wall is lifted upward and outward. The chest cavity takes up more space and the lungs expand. When this happens, the air pressure inside the lungs is less than the air pressure outside the body.

9. Pulling it down… When the air pressure inside is lesser the air outside moves into the nostrils. This movement of air is called INHILATION.

10. Letting it go…. When you released your hand from the rubber balloon, the balloons inside returned to their original position. As the diaphragm relaxes, the rib muscles also relax so the chest cavity becomes smaller.

11. Letting it go …. The pressure inside the chest cavity becomes greater than the pressure outside. The difference in pressure pushes the air out of the lungs. When air is pushed out of the lungs then it is called EXHALATION.

12. Looking Back The rib cage and the diaphragm are important in the breathing process. When you inhale, the ribs move upward and outward while the diaphragm moves downward.

13. Breathing In Movements The volume of the chest cavity becomes larger. The pressure inside it is lower than the air pressure outside your body. Air is drawn into the lungs by the atmospheric pressure outside the body.

14. Looking Back When you exhale, the ribs move downward and inward while the diaphragm moves upward. These actions make the chest cavity smaller.

15. Breathing Out Movements The pressure in the chest cavity becomes greater than the air outside the body. This causes the air to rush out of the lungs and out of the body.

16. THE END