BRONCHIOLES

BRONCHIOLES

Function: air conducting ducts that supply each pulmonary lobule.

Composition:

Cells:

Ciliated cells - the most numerous of the cell types, extend through the full thickness of the epithelium
Mucus (goblet) cells - are interspersed among the ciliated cells and also extend through the full thickness of the epithelium

Function: unicellular mucin-secreting glands

Brush cells -columnar cells that bear microvilli. The basal surface is in synaptic contact with the afferent nerve endings

Function: receptor cells of general sensation

Small granule cells - their cytoplasm processes is sometimes observed extending to the lumen and cytoplasm contains numerous, membrane-bonded, dense-core granules

Function: release polypeptide hormones and/or catecholamines that are thought to function in reflexes regulating the airway or vascular caliber

Function: serve as a reserve population by maintaining individual cell replacement in the epithelium

Function: the smallest air conducting ducts that supply each pulmonary acini

Composition:

Cells:

Function: secretion of surface-active lipoprotein that prevents luminal adhesion

Function: receptor cells of general sensation

Function: release polypeptide hormones and/or catecholamines that are thought to function in reflexes regulating the airway or vascular caliber

Function: serve as a reserve population by maintaining individual cell replacement in the epithelium.

Function: transitional zone concerned with both air conduction and gas exchange between air and blood

Composition:

Simple cuboidal epithelium with ciliated cells and Clara cells as predominating cell types
Lamina propria - loose connective tissue with numerous elastic fibers
Separated circumferential smooth muscle fibers
Adventitia - loose connective tissue
Scattered, thin-walled outpocketings - alveoli extend from the lumen