Final answer:
The bronchioles are small airways branching from the larger bronchi, and the alveoli are tiny sacs at the end of these airways where gas exchange occurs. The structure of the alveoli, with their large surface area and thin walls, is optimized for efficient gas exchange. The air pathway in the respiratory system starts at the nasal cavity and ends in the alveoli.
Step-by-step explanation:
In matching the letters to the structures in a picture of bronchioles and alveoli, one would identify the bronchioles as the smaller passageways branching from the larger bronchial tubes and the alveoli as the tiny bubble-like structures at the end of these passageways. The function of the alveoli is crucial for gas exchange, where oxygen diffuses into the blood and carbon dioxide is expelled from it. This process is optimized by the large surface area of the alveoli, approximately 100 m², similar to half a tennis court, and their thin walls that facilitate the diffusion of gases.
The air flow through the respiratory system follows a pattern that starts from the nasal cavity, moves through the larynx and trachea, into the bronchi, further into bronchioles, and finally reaches the alveoli where gas exchange occurs. The bronchial tubes are constructed of cartilage and smooth muscle, which are innervated by the parasympathetic and sympathetic nervous systems affecting bronchial and bronchiolar contraction and relaxation, ensuring airflow regulation within the lungs.