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A bronchus (/ ˈ b r ɒ ŋ k ə s / BRONG-kəs; pl.: bronchi, / ˈ b r ɒ ŋ k aɪ / BRONG-ky) is a passage or airway in the lower respiratory tract that conducts air into the lungs.The first or primary bronchi to branch from the trachea at the carina are the right main bronchus and the left main bronchus.
The bronchioles (/ ˈ b r ɑː ŋ k i oʊ l s / BRONG-kee-ohls) are the smaller branches of the bronchial airways in the lower respiratory tract.They include the terminal bronchioles, and finally the respiratory bronchioles that mark the start of the respiratory zone delivering air to the gas exchanging units of the alveoli.
The afferents of the tracheobronchial glands drain the lungs and bronchi, the thoracic part of the trachea and the heart; some of the efferents of the posterior mediastinal glands also end in this group.
At the end of the fourth week, the lung bud divides into two, the right and left primary bronchial buds on each side of the trachea. [56] [57] During the fifth week, the right bud branches into three secondary bronchial buds and the left branches into two secondary bronchial buds. These give rise to the lobes of the lungs, three on the right ...
The cells in the respiratory epithelium are of five main types: a) ciliated cells, b) goblet cells, c) brush cells, d) airway basal cells, and e) small granule cells (NDES) [6] Goblet cells become increasingly fewer further down the respiratory tree until they are absent in the terminal bronchioles; club cells take over their role to some extent here. [7]
Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by chronic respiratory symptoms and airflow limitation. [8] GOLD 2024 defined COPD as a heterogeneous lung condition characterized by chronic respiratory symptoms (dyspnea or shortness of breath, cough, sputum production or exacerbations) due to abnormalities of the airways (bronchitis ...
It branches off into two bronchial tubes, a left and a right main bronchus. The bronchi branch off into smaller sections inside the lungs, called bronchioles. These bronchioles give rise to the air sacs in the lungs called the alveoli. [10] The lungs are the largest organs in the lower respiratory tract.
After the lung buds have formed, they begin to grow and branch forming a primitive version of the bronchial tree, determining how the lobes of the lung will be arranged in the mature organ. [2] The first stage of alveolar development, spanning between the fifth and the 16th week of development, is called the pseudoglandular stage . [ 5 ]