ANATOMY

Detailed explanation-1: -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.

Detailed explanation-2: -When you breathe out (exhalation), the diaphragm moves up and the chest wall muscles relax, causing the chest cavity to get smaller and push air out of the respiratory system through the nose or mouth.

Detailed explanation-3: -As they relax they position rib cage downwards and inwards. As the space in the chest cavity gets smaller, the air rich in carbon dioxide is forced out of your lungs and windpipe, and then out of your nose or mouth. Hence During exhalation, the ribs move downwards.