Alveolar ducts

Alveolar duct Airway distal to respiratory bronchiole leading to individual alveoli and alveolar sacs. 

Branching from the terminal bronchioles are the respiratory bronchioles. This is the first generation of airways to have alveoli in their walls. Finally, there are the alveolar ducts which are completely lined with alveolar sacs. This region, from the respiratory bronchioles through the alveoli, is referred to as the respiratory zone, which comprises most of the lungs and has a volume of about 3000 ml at the end of a normal expiration. 

Decrease in lung capacity, alveolar volume, and diffusing capacity for carbon monoxide values remained depressed for at least 72 h after last exposure. Persistent inflammation of proximal portion of alveolar ducts and adjacent alveoli. 

Parenchymal changes affect the gas-exchanging units of the lungs (alveoli and pulmonary capillaries). Smoking-related disease most commonly results in centrilobular emphysema that primarily affects respiratory bronchioles. Panlobular emphysema is seen in AAT deficiency and extends to the alveolar ducts and sacs. 

The sites of action and effects of ozone and other photochemical oxidants are described in Chapters 8 and 9. Recent work with primates has suggested that ozone is absorbed along the entire respiratory tract, penetrates more into the peripheral nonciliated airways, and causes more lesions in the respiratory bronchioles and alveolar ducts as the inhaled ozone concentration increases from 0.2 to 0.8 ppm. The most common and most severe tissue damage was observed in the respiratory bronchioles. The ciliated cells in the terminal bronchioles and the Type 1 cells in the epithelial layer of the proximal alveoli of rats were the... 

Continuous for up to 3 weeks Morphologic changes in distal and respiratory bronchioles, alveolar ducts, and associated alveoli Young rat 72... 

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 the early stages of the disease, fibrotic lesions can be found in the bronchioles and alveolar ducts of the pulmonary tree. If exposure to asbestos is not documented in the patient s life history, laboratory examination (tissue analysis), to demonstrate of the presence of asbestos fibers and ferruginous bodies is necessary. However, the demonstration of these bodies in the ab-... 

The lower respiratory tract (pulmonary region or alveolar ducts and sacs) is the area where gas exchange occurs. Alveolar sacs, clusters of two or more alveoli, branch from alveolar ducts. It is generally considered that there is a total of approximately 300 million alveoli in the lungs of adult humans. The total alveolar surface area in the lungs of adult humans is... 

Atrium. The upper chamber of each half of the heart the portion of nasal cavity in the lung, a subdivision of the alveolar duct from which alveolar sacs open. 

Chronotropic. Affecting the time or rate, as the rate of contraction of the heart. Clara cells. Unciliated cells occurring at the boundary where alveolar ducts branch from the bronchioles. 

The hyperplasia occurred in bronchiolar epithelial cells, often extending into the alveolar ducts (NTP 1989). ... 

Conducting Bronchiole Terminal Bronchiole Respiratory Bronchiole Alveolar Duct... 

Inhaled particles of 20 [im diameter or more tend to be retained in upper parts of the respiratory tract (trachea, pulmonary bronchi and terminal bronchioles) and then removed by ciliary action. In contrast, smaller particles of around 6 pm diameter reach all parts of the respiratory system including the alveolar sacs. Smaller (2 pm) and very small particles (0.2 pm) may not reach the alveolar sacs, only the terminal bronchioles and alveolar ducts. Particles of diameter 1 pm or less may be absorbed if they reach the alveolar sacs. 

An alveolar region or respiratory zone, which includes the alveolar ducts and the alveoli where the gas exchange takes place. 

The transition zone consists of the respiratory bronchioles (generations 17 to 19), which contain alveoli. At the terminal end, the respiratory zone is composed of parenchyma that contains the alveolar ducts and about 300 million alveoli (alveolar sacs) to provide the gas-exchange surface. Since the surface area expands to such a large extent within the very last generations of bifurcations, the inhalation airflow rapidly slows down to zero velocity so that the movement of gas molecules and the exchange occurs entirely by diffusion (Stocks and Hisloop 2002). 

Stratified squamous to mucociliated epithelium with olfactory cells Mucociliated epithelium (ciliated, mucous cells, basal cells) smooth muscle cells fibroblasts neuroendocrine cells immune cells Mucociliated epithelium with Clara cells in distal bronchioles and alveolar ducts... 

Alveolar ducts 20-22 0.3 Alveolar type I Alveolar type II 0.1-0.5... 

This is also referred to as the respiratoiy airways , peripheral airways or pulmonary region , comprising the respiratory bronchioles, alveolar ducts and alveoli. 

Terminal bronchiole Respiratory bronchiole Alveolar ducts and sacs... 

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