What is the main purpose of segmental bronchi in the lungs?

• A. Connect main stem bronchi to alveoli
• B. Provide air conduction to specific lung lobes
• C. Facilitate blood supply to lung tissues
• D. Control local resistance to airflow

Answer: (B)

The main purpose of segmental bronchi in the lungs is to provide air conduction to specific lung lobes. Segmental bronchi are the branches of the main bronchi that extend into each lobe of the lungs, allowing for efficient distribution of air. Each segmental bronchus corresponds to a specific bronchopulmonary segment, which is a functionally and anatomically distinct portion of the lung that is responsible for its own air supply and gas exchange. This structure ensures that each segment of the lung receives the appropriate airflow necessary for optimal gas exchange and respiratory function.

The segmental bronchi also play a critical role in maintaining the overall structure of the respiratory system by ensuring that air is effectively routed to different areas of the lungs, thereby enhancing ventilation and reducing the risk of collapse in certain regions. This targeted distribution of airflow is vital for lung function and helps optimize the use of lung tissue for oxygen and carbon dioxide exchange.

Other options involve functions that do not align with the specific role of segmental bronchi. Although controlling local resistance to airflow is important in the respiratory system, it is more accurately attributed to the bronchioles and smooth muscle rather than segmental bronchi themselves.