what happens to your diaphragm when you exhale

When you exhale, your diaphragm and rib muscles relax, reducing the space in the chest cavity. As the chest cavity gets smaller, air is forced out of the lungs. The diaphragm, located below the lungs, is the major muscle of respiration. It contracts rhythmically and continually, and most of the time, involuntarily. Upon inhalation, the diaphragm contracts and flattens, and the chest cavity enlarges. This contraction creates a vacuum, which pulls air into the lungs. Upon exhalation, the diaphragm relaxes and returns to its domelike shape, and air is forced out of the lungs.