15Breathing In 1. Diaphragm pushes down and the rib cage expands. 2. Thoracic cavity expands in size.3. Air rushes in to fill that space.
16Diaphragm’s Role in Breathing When the diaphragm contracts, the chest cavity enlarges, reducing the pressureinside. To equalize the pressure, air rushes into the lungs. When the diaphragm re-laxes, the elasticity of the lungs and chest wall pushes air out of the lungs.Chest contractsDiaphragm relaxesChest expandsSternumRibsLungDiaphragmcontractsInhalationExhalation
17Breathing Out 1. Diaphragm pushes up and the rib cage pushes back. 2. The size the thoracic cavity shrinks.3. The smaller overall space pushes the air out of the lungs.