Final answer:
Air enters through the nasal cavity, then passes through the pharynx, larynx, trachea, bronchi, bronchioles, and finally arrives to the alveoli where gas exchange occurs.
Step-by-step explanation:
When air enters the body through the nasal cavity, it makes its journey to the alveolus for gas exchange. From the nasal cavity, the air passes through the pharynx (throat), then moves down the larynx (voice box), into the trachea (windpipe). Here in the chest, the trachea divides into the right and left bronchi, leading into each lung. The bronchi branch into smaller tubes called bronchioles, which continue to branch off until they terminate in clusters of tiny air sacs called alveoli. Inside the alveoli, gas exchange takes place; oxygen diffuses into the blood, and carbon dioxide diffuses out of the blood to be exhaled. This pathway is crucial for respiration, a key process in the human body.