Bronchial regions

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... 

Figure 7. Doses to the bronchial region and segmental bronchi as a function of breathing rate, relative to values for miners breathing at 1.2 m h . ...

Figure 10, Doses to the bronchial region (solid curves) and to segmental bronchi in newborn infants and children of various ages, relative to values for adults.

The oral LD50 value for rat is 5.9 g kg whereas the LC50 is 60 000 ppm (30 min exposure). Acute exposures to butanal vapors induce inflammation of the alveolar and bronchial regions of the lung, with death due to pulmonary edema. Severe irritation of... 

More noninvasive markers are needed for assessing early alterations in lung structure. The cells of the nasal, tracheal, and bronchial regions can be... 

Upper bronchial region trachea and bronchi (large ciliated thoracic airways)... 

Lower bronchial region bronchioles (small ciliated thoracic airways) Alveolar region nonciliated thoracic airways and airspaces... 

When an aerosol enters the respiratory tract, its particles first experience inertial transport onto airway surfaces in the extrathoracic and upper bronchial region. 

In the bronchial region, particle deposition is less dependent on flow rate and breathing-cycle period (Fig. 11). It is due to impaction in upper thoracic airways and dne to sedimentation in lower thoracic airways. 

These conditions are specified in Fig. 15. More than 50% of the mass deposited in the entire respiratory tract can be specified in the extrathoracic, lower bronchial, and alveolar regions. Only targeting of the upper bronchial airways is not possible. However, when extrathoracic and upper bronchial regions are com-... 

To inhale the aerosols labelled with radioisotopes (radioactive aerosols), subjects breathe through a mouth piece. The volume of air in the mouth and tracheo-bronchial region is respiratory dead space, and the activity reaching the pulmonary region depends on the volume of air inhaled as well as the deposition in the tracheo-bronchial region. To obtain reproducible results, subjects take breaths of predetermined volume, and the breathing cycle is also standardised, usually at 14 or 15 breaths/min. Exhaled aerosol is collected on a filter, and the deposition in the mouth also estimated, so that the deposition in the lung (tracheo-bronchial... 

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