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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 respiratory bronchioles are the narrowest airways of the lungs, 0.5 mm across. [4] The bronchi divide many times before evolving into the bronchioles. The respiratory bronchioles deliver air to the exchange surfaces of the lungs. [5] They are interrupted by alveoli which are thin walled evaginations.
In the upper respiratory system of mammals there are submucosal glands in the airways, notably in the sinuses, the trachea and the bronchial tubes. [1] In the visual systems of mammals. In the auditory systems of mammals. In the throat there are the esophageal submucosal glands, the submucosal glands of the esophagus.
Mucus is made up of a fluid component of around 95% water, the mucin secretions from the goblet cells, and the submucosal glands (2–3% glycoproteins), proteoglycans (0.1–0.5%), lipids (0.3–0.5%), proteins, and DNA. [7] The major mucins secreted – MUC5AC and MUC5B - are large polymers that give the mucus its rheologic or viscoelastic ...
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]
In these states of immunodeficiency, there is a weakened or absent immune system response to severe infections that repeatedly affect the lung and eventually result in bronchial wall injury. [40] HIV/AIDS is an example of an acquired immunodeficiency that can lead to the development of bronchiectasis.
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 ...
These lymph nodes form four main groups including paratracheal, tracheobronchial, bronchopulmonary and pulmonary nodes.. Paratracheal nodes are located on either side of the trachea.