MICROANATOMY

Detailed explanation-1: -Bronchioles. Bronchioles arise from segmental bronchi and represent the smaller branches of the bronchial tree. They differ histologically from bronchi as they lack C shaped cartilages in their walls.

Detailed explanation-2: -Bronchi undergo multiple divisions and eventually give rise to the terminal bronchioles, which by definition, lack cartilage. The most distal respiratory bronchioles and alveoli are in charge of gas exchange.

Detailed explanation-3: -The bronchioles are lined by simple cuboidal ciliated epithelium, have no hyaline cartilage or submucosal glands, and are surrounded by elastic fibers and smooth muscle. In addition, the club cell is the major cell type in the epithelium of bronchioles.

Detailed explanation-4: -Bronchioles, which are about 1 mm in diameter, further branch until they become the tiny terminal bronchioles, which lead to the structures of gas exchange. There are more than 1000 terminal bronchioles in each lung. The muscular walls of the bronchioles do not contain cartilage like those of the bronchi.

Detailed explanation-5: -As stated, these bronchioles do not have hyaline cartilage to maintain their patency. Instead, they rely on elastic fibers attached to the surrounding lung tissue for support. The inner lining (lamina propria) of these bronchioles is thin with no glands present, and is surrounded by a layer of smooth muscle.