To sort the respiratory structures in the correct order of air flow, we start from the trachea and move toward the alveoli. The correct sequence is as follows:
- Primary bronchi
- Secondary bronchi
- Tertiary bronchi
- Terminal bronchioles
- Respiratory bronchioles
- Alveolar sacs
- Alveoli
Explanation:
1. The trachea branches into two primary bronchi that lead into the lungs. Primary bronchi are the first division of the airways.
2. Each primary bronchus divides into secondary bronchi, one for each lobe of the lung, providing further distribution of air.
3. The secondary bronchi then branch into tertiary bronchi, which continue to subdivide into smaller passages.
4. These smaller bronchi further divide into terminal bronchioles, the last part of the conducting zone where no gas exchange occurs.
5. From the terminal bronchioles, air reaches the respiratory bronchioles, which are the beginning of the respiratory zone and are involved in gas exchange.
6. The air then flows into alveolar sacs, clusters of alveoli that allow for maximum surface area for gas exchange.
7. Finally, the air enters the alveoli, the microscopic air sacs where oxygen and carbon dioxide exchange occurs. This sequence is essential for understanding how air travels through the respiratory system and the sites where it participates in gas exchange.