Under normal circumstances, the defense has improved respiratory function, the inhaled air can play a filtration, heating and humidification role ; ciliary movement and airway mucosal surfaces such as cough reflex , take to clear the airway foreign bodies and pathogenic microorganisms. Lower respiratory tract there secretory IgA, the role of pathogenic microorganisms. Therefore , to maintain the airway generally purified state. Systemic or local defense respiratory and immune dysfunction, especially the elderly, are vulnerable to chronic bronchitis and recurrent rather than more.
1 , smoking
The main factor in the pathogenesis of the disease , cigarettes contain tar , nicotine and hydrogen cyanide and other chemicals that can damage the airway epithelial cells, cilia movement dysfunction and macrophage phagocytosis reduced, resulting in decreased airway purification . And can stimulate the submucosal receptors that parasympathetic hyperactivity , causing bronchial smooth muscle contraction, resulting in increased airway resistance, and glandular secretion, goblet cell hyperplasia , bronchial mucosal edema , mucus accumulation , likely to cause infection. In addition , cigarette smoke also enable increased production of toxic oxygen free radicals induce the release of neutrophil proteases, inhibiting anti-protease systems, destruction of lung elastic fibers , induced emphysema occur. Studies have shown that the prevalence of smokers with chronic bronchitis compared to no smokers 2 to 8 times longer smoked , the greater the amount of smoke is also higher prevalence .
2 , air pollution and harmful gases
Such as sulfur dioxide , nitrogen dioxide, ozone, chlorine and airway epithelium were stimulated and cytotoxicity . According to the report of smoke or sulfur dioxide in the air over 1000mu; g/m3 , the AECB will significantly increase. Others such as silica dust , coal dust , sugar cane dust , lint , etc. can also stimulate the bronchial mucosa damage , lung clearance suffered damage , and create conditions for bacterial infections.
3 , infection factors
Infection is an important factor in the occurrence and development of chronic bronchitis . Viruses, mycoplasma and bacterial infections of the disease with acute exacerbation of the main reasons. Virus infection with influenza virus , rhinovirus , adenovirus and respiratory syncytial virus is common. Bacterial infections with Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus bacteria and catarrhal Mora is more common . Secondary bacterial infections occur every virus or mycoplasma infection basic airway mucosal damage on .
4 , allergic factors
Asthmatic patients with chronic bronchitis , and more have allergies , for a variety of allergens stimulate the skin test positive rate is higher, sputum eosinophils and histamine content and the number of IgE in the blood tend to have increased in some patients serum rheumatoid factor positive and abnormal distribution of T lymphocyte subsets , etc., in the opinion of atopic (atopy) and immune factors associated with the occurrence of this disease , but some believe that the quality of应属atopic asthma risk factors, such in fact应属patients with asthma or chronic bronchitis and asthma category .
5 , Other
AECB more in the winter , so one of the important factor in the pathogenesis of meteorological factors shall be considered . Cold air can stimulate the glands secrete mucus and cilia motility increased weaken airway defenses . Can cause bronchial smooth muscle spasm, mucosal vasoconstriction through reflection , local blood circulation disorder , is conducive to secondary infection. Most patients with this disease have autonomic dysfunction phenomenon parasympathetic hyperactivity in some patients , airway reactivity higher than normal . In addition , the elderly adrenal dysfunction, impaired immune function , reduced lysozyme activity , poor nutrition , vitamin A, C deficiency Dengjun airway mucosal vascular permeability changes .
6 , the elderly gonads and adrenal function decline , laryngeal reflexes , respiratory defense function degradation , monocytes - phagocyte system function decline , but also can increase the incidence of chronic bronchitis .
7 , nutrition also has some influence on bronchitis , vitamin C deficiency , the body's resistance to infection decreased, increased vascular permeability ; vitamin A deficiency , can columnar epithelial cells of the bronchial mucosa and mucosa repair miopragia , lysozyme reduce , easy to suffer chronic bronchitis.
8 , whether genetic factors related to the pathogenesis of chronic bronchitis , has not yet been confirmed. alpha; 1 - antitrypsin deficiency by severe can cause emphysema , but no symptoms of airway disease , suggesting that it is not directly related to chronic bronchitis.