The movement of the diaphragm causes air to go in and out of the lungs through its rhythmic contraction and relaxation, which changes the volume and pressure inside the chest cavity. How inhalation occurs:
- When you inhale, the diaphragm contracts and flattens, moving downward from its dome-shaped resting position.
- This contraction enlarges the chest cavity and increases the volume inside the thoracic (chest) space.
- As the chest cavity volume increases, the pressure inside it decreases relative to the outside air pressure, creating a vacuum effect.
- This lower pressure inside the lungs causes air to be drawn into the lungs to equalize the pressure difference
How exhalation occurs:
- When you exhale, the diaphragm relaxes and returns to its dome shape, moving upward into the chest cavity.
- This reduces the volume of the chest cavity and increases the pressure inside it.
- The higher pressure inside the lungs pushes air out of the lungs into the atmosphere
The diaphragm works together with the intercostal muscles between the ribs, which also help expand and contract the rib cage during breathing, further aiding the changes in chest cavity volume and pressure that move air in and out of the lungs
. In summary, the diaphragm's downward movement during contraction creates more space and lower pressure in the chest, pulling air in, while its upward movement during relaxation decreases space and increases pressure, pushing air out of the lungs
