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MECHANISM OF BREATHING:

1. During inhalation :The intercostal muscles contract causing the rib cage to
move upward and outward, and the diaphragm contracts and move downward.
The upward and outward movement of rib cage, as well as the downward
movement of diaphragm, both increase the space in the chest cavity and make it
larger. As the chest cavity becomes larger, air is sucked in from outside into the
lungs. The lungs get filled up with air and expand.

2. During exhalation:The intercostal muscles relax causing the rib cage to move
downward and inward, and the diaphragm relaxes and move upward. The
downward and inward movement of rib cage, as well as the upward movement of
diaphragm, both decrease the space in our chest cavity and make it smaller. As
chest cavity becomes smaller, air is pushed out from the lungs.

Inhalation Exhalation

Rib cage moves upward Rib cage moves
and outward downward and inward

Diaphragm contracts Diaphragm relaxes and
and move downward. move upward.

Space in the chest cavity space in the chest
increases. decreases.

Air gets pulled into the Air is forced out of the
lungs respiratory tract

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