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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.
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 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.
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]
The trachea (pl.: tracheae or tracheas), also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all animals lungs. The trachea extends from the larynx and branches into the two primary bronchi.
Bronchial buds continue to branch as development progresses until all of the segmental bronchi have been formed. Beginning around week 13, the lumens of the bronchi begin to expand in diameter. By week 16, respiratory bronchioles form. The fetus now has all major lung structures involved in the airway.
A bronchopulmonary segment is a portion of lung supplied by a specific segmental bronchus and its vessels. [1] [2] These arteries branch from the pulmonary and bronchial arteries, and run together through the center of the segment. Veins and lymphatic vessels drain along the edges of the segment.