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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.
Instead of hard cartilage, the bronchi and bronchioles are composed of elastic tissue. The lungs are made up of thirteen different kinds of cells, eleven types of epithelial cell and two types of mesenchymal cell. [13] The epithelial cells form the lining of the tracheal, and bronchial tubes, while the mesenchymal cells line the lungs.
The lobar bronchi branch into tertiary bronchi also known as segmental bronchi and these supply air to the further divisions of the lobes known as bronchopulmonary segments. Each bronchopulmonary segment has its own (segmental) bronchus and arterial supply. [8] Segments for the left and right lung are shown in the table. [5]
The first bronchi to branch from the trachea are the right and left main bronchi. Second, only in diameter to the trachea (1.8 cm), these bronchi (1–1.4 cm in diameter) [ 5 ] enter the lungs at each hilum , where they branch into narrower secondary bronchi known as lobar bronchi, and these branch into narrower tertiary bronchi known as ...
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 ...
Another important cell type is the pulmonary neuroendocrine cell. These are innervated cells that only make up around 0.5% of the respiratory epithelial cells. [7] The ciliated cells are columnar epithelial cells with specialized ciliary modifications. The ciliated cells make up between 50 and 80 per cent of the epithelium. [8]
Infection-induced iBALT structures contained CD4+ T cells, B220+ B cells (D), and CD21+ follicular dendritic cells (E). Bronchus-associated lymphoid tissue (BALT) is a tertiary lymphoid structure. It is a part of mucosa-associated lymphoid tissue (MALT), and it consists of lymphoid follicles in the lungs and bronchus. BALT is an effective ...
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.