Final answer:
Air enters the respiratory system through the nose, where it is filtered, warmed, and moistened, then travels through the pharynx, larynx, trachea, bronchi, bronchioles, and finally into alveolar sacs containing alveoli, where gas exchange occurs.
Step-by-step explanation:
The pathway of air during the respiratory process starts at the nose and involves several key structures before reaching the alveoli for gas exchange. Initially, air enters through the nasal cavity, where it is warmed, moistened, and filtered. It then passes through the pharynx and larynx, entering the trachea, which is the main airway leading to the lungs. The trachea bifurcates into the left and right bronchi, each leading to a lung. The bronchi continue to divide into smaller tubes called bronchioles, which eventually terminate in clusters of air sacs known as alveolar sacs. These sacs contain the alveoli, where the crucial gas exchange with the bloodstream takes place. Oxygen is diffused into the blood, and carbon dioxide is diffused out, to be expelled from the body upon exhalation.