THORAX ABDOMEN AND PELVIS

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: -During inspiration, the diaphragm contracts and the thoracic cavity increases in volume. This decreases the intraalveolar pressure so that air flows into the lungs. Inspiration draws air into the lungs.

Detailed explanation-3: -Action: diaphragm is the main inspiratory muscle, during inspiration it contracts and moves in an inferior direction that increases the vertical diameter of the thoracic cavity and produces lung expansion, in turn, the air is drawn in.

Detailed explanation-4: -The diaphragm contracts and flattens during inspiration to increase the volume of the thoracic cavity. The increase in volume causes a decrease in intra-alveolar pressure, pressure lower than the atmospheric pressure, and creates a pressure gradient.