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Smoking exposes delicate cells inside the lungs directly to these compounds. This causes mutations in the DNA of the cells, which leads to cancer. According to the World Health Organization's report, "Tobacco Smoke and Involuntary Smoking", 80 percent of all cases of lung cancer are attributable to smoking.
The hyperplasia of airway basal cells is the earliest indication of smoking-related abnormality in the lung. [4] [1] This is followed by shortened cilia, loss of ciliated cells, mucous cell hyperplasia, and loss of cell junctions giving a leaky epithelial barrier. With persistent stress from smoking, the basal cells become disarranged and lose ...
Another important cell type is the pulmonary neuroendocrine cell. These are innervated cells that only make up around 0.5% of the respiratory epithelial cells. [7] The ciliated cells are columnar epithelial cells with specialized ciliary modifications. The ciliated cells make up between 50 and 80 per cent of the epithelium. [8]
The cilia are hair-like, microtubular-based structures on the luminal surface of the epithelium. On each epithelial cell there are around 200 cilia that beat constantly at a rate of between 10 and 20 times per second. The cilia are surrounded by a periciliary liquid layer (PCL), a sol layer that is overlain with the gel layer of mucus. [9]
Though smoking leads to an overall decrease in DNA methylation, several critical genes become hypermethylated. Two of the most noteworthy of these genes are p16 and p53. These genes are critical to cell cycle regulation and were shown to have higher levels of methylation in smokers than in non smokers. [3]
Primary ciliary dyskinesia (PCD) is a rare, autosomal recessive genetic ciliopathy, that causes defects in the action of cilia lining the upper and lower respiratory tract, sinuses, Eustachian tube, middle ear, fallopian tube, and flagella of sperm cells. The alternative name of "immotile ciliary syndrome" is no longer favored as the cilia do ...
Cigarettes are known to cause many lung diseases including emphysema, chronic bronchitis, and lung cancer. Smoker's macrophages are alveolar macrophages whose characteristics, including appearance, cellularity, phenotypes, immune response, and other functions, have been affected upon the exposure to cigarettes. [1]
Mammals also have motile cilia or secondary cilia that are usually present on a cell's surface in large numbers (multiciliate), and beat in coordinated metachronal waves. [40] Multiciliated cells are found lining the respiratory tract where they function in mucociliary clearance sweeping mucus containing debris away from the lungs . [ 13 ]