Club cells, also known as bronchiolar exocrine cells, and originally known as Clara cells, are dome-shaped cells with short microvilli, found in the small airways ( bronchioles) of the lungs. Club cells are found in the ciliated simple epithelium. These cells may secrete glycosaminoglycans to protect the bronchiole lining.
Club cells, also known as bronchiolar exocrine cells, and formerly known as Clara cells, are dome-shaped with short, found in the small airways of the.Club cells are found in the ciliated simple epithelium. These cells may secrete to protect the bronchiole lining. Bronchiolar cells gradually increase in number as the number of decrease.One of the main functions of club cells is to protect the bronchiolar. They do this by secreting a small variety of products, including club cell secretory protein, and a solution similar in composition to. They are also responsible for detoxifying harmful substances inhaled into the lungs. Club cells accomplish this with enzymes found in their.
Club cells also act as a, multiplying and differentiating into ciliated cells to regenerate the bronchiolar epithelium. Contents.Function The respiratory bronchioles represent the transition from the conducting portion to the respiratory portion of the respiratory system. The narrow channels are usually less than 2 mm in diameter and they are lined by a simple cuboidal epithelium, consisting of ciliated cells and non-ciliated club cells, which are unique to bronchioles. In addition to being structurally diverse, club cells are also functionally variable.
One major function they carry out is the synthesis and secretion of the material lining the bronchiolar. This material includes glycosaminoglycans, proteins such as, and conjugation of the secretory portion of IgA antibodies. These play an important defensive role, and they also contribute to the degradation of the mucus produced by the upper airways. The heterogeneous nature of the dense granules within the club cell's cytoplasm suggests that they may not all have a secretory function. Some of them may contain lysosomal enzymes, which carry out a digestive role, either in defense: Club cells engulf airborne toxins and break them down via their cytochrome P-450 enzymes (particularly CYP4B1, which is only present in the club cells) present in their smooth endoplasmic reticulum; or in the recycling of secretory products.
Club cells are mitotically active. They divide and differentiate to form both ciliated and non-ciliated epithelial cells.Clinical significance Club cells contain, which is believed to be responsible for cleaving the surface protein of virus, thereby activating it and causing the symptoms of flu. When the protein is disrupted in mice, these mice display severe at birth as a result of disorganization of the and formation of aberrant vesicular structures within club cells.Malignant club cells are also seen in bronchioalveolar carcinoma of the lung.Serum club cell proteins are used as a biomarker of lung permeability. Exposure to particulate air pollution may compromise the integrity of the lung epithelium and lead to rapid increase in epithelial barrier permeability, as reflected by increased serum club cell concentrations. History Club cells were previously called Clara cells, as they were first described by (1899–1966), in 1937.
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The Clara cells are a group of cells, sometimes called 'nonciliated bronchiolar secretory cells', found in the bronchiolar epithelium of mammals including man, and in the upper airways of some species such as mice. Their secretory function is assumed from their ultrastructural appearance, that usually includes copious smooth endoplasmic reticulum, many apical mitochondria and scanty secretory-like dense vesicles near the luminal membrane. An apical cap of the cell usually bulges into the airway lumen, and secretion may be by shedding this cap, or by diffusion secretion or by merocrine secretion in individual granules. The chemical nature of the secretion probably includes protein, glycoprotein and lipids. The secretion may contain enzymes.
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Its function is presumably to determine the chemical and physical properties of the lining of small airways, and it could behave as a kind of bronchiolar surfactant, limiting lung collapse. The Clara cells also contain much cytochrome P450 dependent mixed-function oxidases, which presumably play a detoxifying role.
It is not known whether these oxidases can be secreted or whether they have a lipid-synthesizing function. Clara cells may be important in human disease, both by giving rise to tumours and by taking part in metaplastic changes in bronchiolar disease.