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 flattens and moves downward, increasing the chest cavity's volume. This expansion decreases the air pressure inside the lungs compared to the outside atmosphere, creating a vacuum that pulls air into the lungs for inhalation. When the diaphragm relaxes, it returns to its dome shape, reducing the chest cavity's volume, which increases the pressure inside the lungs and pushes air out for exhalation. This rhythmic contraction and relaxation of the diaphragm is the primary mechanism that drives breathing by facilitating the inflow and outflow of air in the lungs.
How Diaphragm Movement Affects Breathing
- On inhalation, diaphragm contracts and flattens → chest cavity volume increases → lung pressure drops → air rushes in.
- On exhalation, diaphragm relaxes and domes upward → chest cavity volume decreases → lung pressure rises → air is pushed out.
Summary
The diaphragm acts as a pump; its downward movement creates a vacuum for air to enter, and its upward relaxation expels the air, allowing oxygen to enter the body and carbon dioxide to leave during breathing cycles.
