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Pathology caused by adverse environmental factors that are inhaled.
Nowadays, the structure of diseases caused by adverse environmental factors has undergone significant changes due to the manifestation of various pathways of xenobiotics into the human body. During evolution, the bulk of toxic products entered the body through the gastrointestinal tract and rendered harmless in the liver. Currently, the majority of foreign products enter the human body through the lungs, which is due to an increase in their concentrations in the atmospheric air, as well as the gigantic dimensions of the airborne barrier (80 m when exhaling and 120 m when inhaling), which is the largest membrane of the body at the border with external environment, the protection of which is ensured by a complex of mechanisms of broncho-pulmonary protection. In addition, there are indications that a person is more sensitive in toxic substances entering through the lungs than through the gastrointestinal tract: the MPC of the same substance in water and in atmospheric air are different. It becomes clear the increase in the prevalence of respiratory pathology these days: chronic obstructive diseases, bronchial asthma, interstitial lung diseases, lung cancer. This led to the emergence of a new branch of pulmonology - "Environmental pulmonology". Environmental pulmonology is a section of pulmonary pathology that studies diseases of the respiratory organs caused by chemical and physical factors of natural, technogenic and domestic origin (Velichkovsky B.T., 2001). The defense mechanisms of the bronchopulmonary system operate at the level of the conducting and respiratory departments of the lung and are carried out by air conditioning, mechanical cleaning, endocytosis with bronchial epithelium, humoral nonspecific protection, cellular nonspecific protection, and immune specific protection. Air conditioning is associated with its heating or cooling, moisturizing in the upper respiratory tract and large bronchi. Mechanical cleaning of the air begins with its filtration during the passage of the nasal cavity. In this case, the inhalation of particles occurs on the mucous membranes of the nose, trachea and bronchi, followed by their removal by sneezing and coughing. The deposition of particles depends on their diameter. So, particles with a diameter of more than 50 microns are trapped in the nasal cavity, 30-50 microns in the trachea, 10-30 microns in the bronchi, 3-10 microns in the bronchioles, 1-3 microns in the alveoli. Particles whose diameter is less than 0.5 microns practically do not linger in the lungs. The most important part of the mechanical cleaning of air from microorganisms and other damaging agents is the mucociliary clearance, acting at the level of the bronchi and bronchioles.
It is provided by the development of the mucous secretion by the mucous glands of the bronchi, goblet cells and Clara cells of the integumentary epithelium, as well as by the beating of the cilia of ciliated cells. The composition of the mucous secretion, in addition to mucus, includes various glycoproteins, proteases, surfactant, IgA. The mucous membrane has a thickness of 5-7 microns and is divided into two layers: at the level of the cilia it is represented by the liquid phase (sol), which provides favorable conditions for their movement, on the surface of the epithelium - by the dense phase (gel). The functioning of the mucociliary system is associated with a delay in the inhaled particles by mucus, followed by their movement due to the beating of the cilia towards the trachea and their removal with a cough reflex. Many conditions are known in which mucociliary clearance is damaged and contributes to the development of acute pneumonia: primary ciliary dyskinesia (Kartagener syndrome), cold or hot air, drugs, tobacco smoke, allergens, slow-reacting anaphylaxis substance, PGE1, PGE2 and leukotriene (accelerate beating cilia). Nonspecific protective factors are produced mainly by polymorphonuclear leukocytes and macrophages that are constantly present in the respiratory tract, as well as serous cells of the glands: interferon, lysozyme, lactoferrin, proteases, antiproteases, secretory immunoglobulin, etc. The cellular mechanisms of nonspecific protection of the lung tissue are of greatest importance in its respiratory departments, where there is no mucociliary system and a secret containing humoral factors of nonspecific protection. The most important cells of this system are the alveolar macrophage, polymorphonuclear leukocyte, labrocyte and eosinophil. The immune mechanisms of the specific protection of the bronchi and pulmonary parenchyma are carried out by lymphoid and macrophage cells of the broncho-associated lymphoid tissue and lymph nodes. Of particular importance is the secretion of IgA and IgG. IgA in large quantities is kept secret and protects the lungs from viral infections, provides agglutination of bacteria and the neutralization of their toxins. IgG of serum and lower respiratory tract agglutinates and opsonizes bacteria, activates complement, accelerating chemotaxis of granulocytes and macrophages, neutralizes bacterial toxins and viruses, and lyses gram-negative bacteria. All of these protection mechanisms provide drainage function of the bronchi, in violation of which there are favorable conditions for the development of acute pneumonia.
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Pathology caused by adverse environmental factors that are inhaled.
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