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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.
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]
A decrease in diameter is called bronchoconstriction, which is the tightening of the smooth muscle surrounding the bronchi and bronchioles due to and stimulated by histamine, parasympathetic nerves, cold air, chemical irritants, excess mucus production, viral infections, and other factors to decrease air flow. Bronchoconstriction can result in ...
The lung has a left-right symmetry and each bud known as a bronchial bud grows out as a tubular epithelium that becomes a bronchus. Each bronchus branches into bronchioles. [55] The branching is a result of the tip of each tube bifurcating. [53] The branching process forms the bronchi, bronchioles, and ultimately the alveoli. [53]
Visualising the interior of the bronchi through a bronchoscope passed through the mouth and trachea, procedure is called bronchoscopy. The carina of the trachea is a hook shaped process projecting backward from the lower margin of lowest tracheal ring. It helps to divide the trachea into two primary bronchi.
The lower respiratory tract is also called the respiratory tree or tracheobronchial tree, to describe the branching structure of airways supplying air to the lungs, and includes the trachea, bronchi and bronchioles. [8] trachea. main bronchus (diameter approximately 1 – 1.4 cm in adults) [9] lobar bronchus (diameter approximately 1 cm)
The primary bronchi enter the lungs to become the intrapulmonary bronchi, which give off a set of parallel branches called ventrobronchi and, a little further on, an equivalent set of dorsobronchi (Fig. 16). [46] The ends of the intrapulmonary bronchi discharge air into the posterior air sacs at the caudal end of the bird.
This branch supplies the superior lobe of the right lung and is the most superior of all secondary bronchi. It arises above the level of the right pulmonary artery, and for this reason is named the eparterial bronchus. [1] All other distributions falling below the pulmonary artery are termed hyparterial.