Respiratory system airways

Respiratory System Airway obstruction Pulmonary infiltrates Pulmonary edem Respiratory depression Nasal congestion... 

Tlie respiratory system is tlie main target organ for vapour, gas or mist. Readily-soluble cheirticals, e.g. chlorine or phosgene, attack the upper respiratory tract less soluble gases, e.g. oxides of nitrogen, penetrate more deeply into the conducting airways and, in some cases, may cause pulmonary oedema, often after a time delay. 

Horsfield, K. (1986). Morphometry of airways. In The respiratory system Section 3. Mechanics of Breathing, Part 1vol. Ill (P.T. Macklem and J. Mead, Eds.), pp. 75-88. American Physio logical Society, Bethesda, Maryland. 

The aerodynamic particle diameter determines the fate of particles in the respiratory system. Coarse particles are deposited in the nose and nasopharynx. Smaller particles that pass the upper airway can be deposited in the bronchial region and lower airway. A size-selective deposition model and sampling of particles has been standardized both in Europe and internationally. The... 

Inhaled gaseous compounds are absorbed in all parts of the respiratory system whereas particle size determines how deep into the airways the parti cles will he transported in the airstrearn. Shortness of breath is a typical sign of a chemical exposure that has affected the lungs, and it may be evoked through iminunological mechanisms (e.g., formaldehyde, ethyleneoxide), or through toxic irritation (formaldehyde, isocyanates, sulfur dioxide, nitrogen dioxide, Frequently the mechanism depends on the concentration ol the com... 

It is the respiratory system that enables an adult human to absorb about 360 litres of oxygen in a typical day and excrete a slightly smaller volume of carbon dioxide. This is made possible by the branching system of airways in the lungs which services a vast surface area for gas exchange. 

Fig. 3.1 Schematic diagram of the human respiratory system. The gross anatomy of the lung, the covering membranes (pleura), airways and air sacs (alveoli) are shown. The average diameter of portions of the air flow system are indicated trachea, 20 mm bronchus, 8 mm terminal and respiratory bronchioles, 0.5 mnn alveolar duct, 0.2 mm alveolar sacs, 0.3 mm.

In experimental animals the respiratory system is a primary target of acrolein exposure after inhalation, and there is an inverse relationship between the exposure concentration and the time it takes for death to occur." Inhalation LCso values of 327ppm for 10 minutes and 130ppm for 30 minutes have been reported in rats." Of 57 male rats, 32 died after exposure to 4 ppm for 6 hours/day for up to 62 days. Desquamation of the respiratory epithelium followed by airway occlusion and asphyxiation is the primary mechanism for acrolein-induced mortality in animals." Sublethal acrolein exposure in mice at 3 and 6 ppm suppressed pulmonary antibacterial defense mechanisms. A combination of epithelial cell injury and inhibition of macrophage function may be responsible for acrolein-induced suppression of pulmonary host defense. ... 

A stands for provision of airway B stands for breathing and ventilation C stands for circulation support D stands for drug-induced depression (central nervous and respiratory system) and E for electrolyte and metabolic abnormalities and... 

Muscarinic antagonists inhibit secretions and relax smooth muscle in the respiratory system. The parasympathetic innervation of respiratory smooth muscle is most abundant in large airways, where it exerts a dominant constrictor action. In agreement with this innervation pattern, muscarinic antagonists produce their greatest bronchodilator effect at large-caliber airways. 

Figure 2.13 shows the deposition of particles in various regions of the respiratory tract as a function of particle diameter (Phalen, 1984 Phalen et al., 1991 Yeh et al., 1996). The deposition fraction of PM1() in the pulmonary and tracheobronchial regions can be quite large, so it is not surprising that health effects could be associated with these particles. Deposition in the upper portions of the respiratory system is dominated primarily by the large particles, which are readily taken out in the nose and upper airways. 

However, the lungs are equipped with defense mechanisms especially with regard to the intake of foreign substances from the air. Thus, the upper airways of the respiratory system are lined with ciliated cells, and mucus is secreted, which also lines the airways. Solid particles are therefore trapped by the mucus and cilia and are transported out of the respiratory system. Other substances may be removed after dissolving in the mucus and then being transported out by the ciliary escalator. 

Volatile irritants such as ammonia and chlorine initially cause constriction of the bronchioles. These two gases are water soluble, are absorbed in the aqueous secretions of the upper airways of the respiratory system, and may not cause permanent damage. Irritant damage may however lead to changes in permeability and edema, the accumulation of fluid. Some irritants such as arsenic compounds cause bronchitis. 

Asthma A chronic disease of the respiratory system characterized by bronchoconstriction, airway inflammation, and the formation of mucous plugs in the airway. 

As shown in Table 18.2, there are many different cell types in the respiratory system with considerable variation in both structure and function from the nasal epithelium to the alveoli. The various cell types of the airway epithelium are shown in Figure 18.2. 

Sulfur dioxide is an irritant to the eyes, skin, mucous membranes, and respiratory system. As a water-soluble gas, it is largely removed in the upper respiratory tract. Its major effect is as a respiratory tract irritant, where it irritates the upper airways and causes bronchioconstriction, resulting in increased airflow resistance.16 Subjects who are hyperresponsive to sulfur dioxide are especially at risk from it. Asthmatics may suffer bronchioconstriction after only a few breaths of... 

Bioavailability from Environmental Media. No studies were located regarding the bioavailability of acrolein from environmental media. Since acrolein has been detected in ambient air and in food and beverages (ppb levels), it is important to determine if acrolein can be absorbed by humans from environmental samples. However, the chemical structure of acrolein makes it a highly reactive molecule, which presumably is why its effects are, for the most part, restricted to the area of exposure (i.e., respiratory system for inhalation exposure or localized skin damage for dermal exposure). The limited information available regarding absorption parameters of acrolein in experimental animals indicates that acrolein is easily retained in the respiratory airways however, virtually no information is available regarding absorption by the gastrointestinal tract or skin. Therefore, based on the data available, it is likely that inhalation of contaminated air will result in irritation of the eyes and respiratory tract. 

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