The movement of the diaphragm causes air to go in and out of the lungs by changing the volume and pressure inside the chest cavity. When the diaphragm contracts, it moves downward, increasing the volume of the chest cavity and decreasing the pressure inside the lungs compared to the outside atmosphere, causing air to flow into the lungs (inhalation). When the diaphragm relaxes, it moves upward into a dome shape, decreasing the volume of the chest cavity and increasing the pressure inside the lungs, which forces air out (exhalation).
How Diaphragm Movement Causes Airflow
- Inhalation : The diaphragm contracts and flattens, pulling downward. This expands the chest cavity and lowers the lung pressure below atmospheric pressure, creating a vacuum that draws air into the lungs.
- Exhalation : The diaphragm relaxes and moves upward, reducing the chest cavity volume. This increases pressure inside the lungs above atmospheric pressure, pushing air out.
This process is the fundamental mechanism behind breathing, facilitated mainly by the diaphragm muscle, often assisted by other muscles during deeper or forced breaths.
Summary
The diaphragm acts as the primary muscle of respiration by controlling the pressure gradient that moves air in and out of the lungs through its rhythmic contraction and relaxation, which changes thoracic cavity volume and lung pressure.
