MEDICAL PHYSIOLOGY

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 the diaphragm contracts, the ribcage expands and the contents of the a bdomen move down ward. This results in a larger chest volume, which decreases air pressure inside the lungs. With lower air pressure inside than outside the lungs, air rushes 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.