1. Inhalation rib cage pulled upward and outward
diaphragm pulled downward

2. Exhalation
Now, we’ll see how we exhale or breathe out.

3. rib cage moves downward and inward rib cage moves downward and inward
Exhalation
When the muscles between the ribs relax, the rib cage moves downward and inward.

4. Exhalation rib cage moves downward and inward
diaphragm moves upward
And when the diaphragm muscles relax, the diaphragm moves upward

5. Exhalation rib cage moves downward and inward
diaphragm moves upward
We’ll watch this happening.

6. the volume inside decreases
Exhalation
As everything is pushing inward, we see the volume inside the chest cavity decreases.

7. the pressure inside increases
Exhalation
This means the pressure inside increases.

8. the pressure inside is higher than atmospheric pressure
Exhalation
Now, the pressure inside the chest cavity is higher than atmospheric pressure. Remember that air moves from an area of higher pressure into an area of lower pressure.

9. Exhalation
So as the volume in the chest cavity decreases, air is pushed out of the lungs.

10. Exhalation
So again, we don’t have muscles in our lungs.

11. Exhalation rib cage moves downward and inward
diaphragm moves upward
It is when the muscles between our ribs and in our diaphragm relax,

12. Exhalation rib cage moves downward and inward
diaphragm moves upward
That the volume of the chest cavity is decreased and air is pushed out.

13. Breathing
Now, we’ll have a look at the whole process of breathing…

14. Breathing
Inhalation……exhalation…..inhalation……exhalation… Of course this process continues to occur throughout our whole lifetime.

15. Acknowledgements for Images Used
"Gray112" by Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 112. Licensed under Public Domain via Wikimedia Commons -