Respiratory: components

The trachea and initial portions of the primary bronchi are extrapulmonary conducting passageways. After passing into the lung, the primary bronchi, their branches and continuing bronchioles constitute the intrapulmonary conducting passageways. These passageways serve to convey air, no gas exchange occurs. Bronchioles lead into respiratory passageways that are distinguished by the presence of alveoli in their walls where gas exchange occurs. Respiratory passageways are all intrapulmonary.

The distal portions of the primary bronchi, their branches and continuing bronchioles comprise the intrapulmonary conducting passageways.

The diagram illustrates both extra- and intrapulmonary regions of the primary bronchi.

Primary bronchi branch into secondary (lobar) and tertiary (segmental) bronchi before transitioning to bronchioles, which constitute the last segments of the intrapulmonary, conducting pathways.

Primary bronchi branch into secondary (lobar) and tertiary (segmental) bronchi before transitioning to bronchioles, which constitute the last segments of the intrapulmonary, conducting pathways.

Intrapulmonary respiratory passageways contain alveoli for gas exchange.

Respiratory bronchioles possess scattered alveoli in their walls and constitute the first site where gas exchange occurs.

Respiratory bronchioles continue as alveolar ducts, in which the wall consist entirely of alveoli. Alveolar ducts end in alveolar sacs, chambers lined by alveoli.

Respiratory bronchioles continue as alveolar ducts, in which the wall consist entirely of alveoli. Alveolar ducts end in alveolar sacs, chambers lined by alveoli.

Alveoli first appear in respiratory bronchioles and are sites where gas exchange occurs.