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Which structures make up the lower airways?
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human respiratory system
The lungs serve as the gas-exchanging organ for the process of respiration.
The lower respiratory tract begins below the larynx and consists of the following primary structures:
- Trachea: A tube approximately 10 to 12 cm long that serves as the main airway, stiffened by horseshoe-shaped cartilage rings.12
- Bronchi: The trachea divides into two stem (or main) bronchi, which enter the lungs. These further subdivide into smaller, narrower branches.132
- Bronchioles: These are the smaller, narrower airways that result from the subdivision of the bronchi. They eventually lead to the gas-exchanging zones of the lung.43
- Lungs: The organs containing the branching airway tree, including the terminal bronchioles, alveoli, and alveolar sacs where gas exchange occurs.42
While the upper respiratory tract includes the nose, nasal passages, pharynx, and larynx, the lower airways are specifically defined by these structures that facilitate the conduction of air into the lungs and the subsequent exchange of gases.452