Final answer:
The primary passage by which air enters the lungs is the trachea. Air travels from the pharynx, through the larynx, into the trachea, then into the bronchi, and ultimately the bronchioles, which conclude in the alveoli for gas exchange.
Step-by-step explanation:
The primary passage by which air enters the lungs is the trachea.
Inhaled air travels through the respiratory system in the following order:
- Pharynx (throat)
- Larynx (voice box)
- Trachea (windpipe)
- Bronchi (the split tubes leading to each lung)
- Bronchioles (smaller airways branching off from the bronchi)
Specifically, after air passes through the larynx, it moves into the trachea, which is a long tube leading down to the chest. In the chest, the trachea divides into the right and left bronchi as it enters the lungs. The bronchi are made of cartilage and smooth muscle and have mucus that traps particles, along with cilia that sweep debris toward the throat. From the bronchi, air flows into the bronchioles, which are even smaller passages ending in alveoli where gas exchange occurs.
Notably, the statement 'The bronchioles branch into bronchi' is incorrect. The correct order is that air travels from bronchi to bronchioles.