What are the two short branches at the lower end of the trachea that direct air into the lungs?

• A. Alveoli
• B. Bronchi
• C. Bronchioles
• D. Tracheoles

Answer: (B)

The two short branches at the lower end of the trachea that direct air into the lungs are known as the bronchi. When air passes through the trachea, it splits into the right and left bronchi, each leading to a lung. This division allows for the distribution of air to both lungs for gas exchange.

The function of the bronchi is essential as they serve as the main passageways for air to enter the lungs. Each bronchus further divides into smaller branches that continue to branch out into even finer tubes called bronchioles, ultimately leading to alveoli where gas exchange occurs.

In contrast, the other options relate to different parts or structures of the respiratory system. Alveoli are the tiny air sacs where the actual exchange of oxygen and carbon dioxide takes place. Bronchioles are smaller branches that stem from the bronchi and lead to alveoli, while tracheoles are a term that is more commonly associated with the respiratory system of insects. Understanding these distinctions helps clarify the roles of each component in respiratory physiology.