Mammal, lung (Gross, Medium)

Structure List Trachea Primary bronchi Tracheal bronchus Secondary bronchus Bronchioles

The trachea conducts air from the larynx to its bifurcation at the TRACHEAL CARINA which forms the two PRIMARY BRONCHI. In ruminants and the pig, a TRACHEAL BRONCHUS branches from the trachea cranial to the carina to supply the right cranial lobe. Each primary bronchus branches into LOBAR (secondary) BRONCHI which supply the various lobes of the lung. Within the lobe of the lung, the lobar bronchi divide into BRONCHIOLES. These bronchioles eventually branch into TERMINAL BRONCHIOLES and RESPIRATORY BRONCHIOLES. Terminal bronchioles are the last of the conducting airways, whereas respiratory bronchioles are the transition between conducting airways and respiratory air spaces. The branching pattern is different in different species.