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: -It is the active phase of ventilation because it is the result of muscle contraction. 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: -[1] Increasing the volume of the thoracic cavity causes a decrease in the intrathoracic pressure and an influx of air. Meanwhile, decreasing the volume of the thoracic cavity generally occurs by the relaxation of the muscles of inspiration, which causes an increase in intrathoracic pressure and results in exhalation.

Detailed explanation-4: -For inspiration, the diaphragm contracts, causing the diaphragm to flatten and drop towards the abdominal cavity, helping to expand the thoracic cavity. The external intercostal muscles contract as well, causing the rib cage to expand, and the rib cage and sternum to move outward, also expanding the thoracic cavity.