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Each respiratory bronchiole supplies the alveoli held in each acinus accompanied by a pulmonary artery branch. The pulmonary lobule is the portion of the lung ventilated by one bronchiole. Bronchioles are approximately 1 mm or less in diameter and their walls consist of ciliated cuboidal epithelium and a layer of smooth muscle .
The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary ...
The respiratory bronchioles represent the transition from the conducting portion to the respiratory portion of the respiratory system. The narrow channels are usually less than 2 mm in diameter and they are lined by a simple cuboidal epithelium, consisting of ciliated cells and non-ciliated club cells, which are unique to bronchioles.
The lungs can be included in the lower respiratory tract or as separate entity and include the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. [3] Adult and pediatric airway anatomy. The respiratory tract can also be divided into a conducting zone and a respiratory zone, based on the distinction of transporting gases or ...
The bronchial circulation is the part of the systemic circulation that supplies nutrients and oxygen to the cells that constitute the lungs, as well as carrying waste products away from them.
The ducts number between two and eleven from each bronchiole. [10] Each duct opens into five or six alveolar sacs into which clusters of alveoli open. Each terminal respiratory unit is called an acinus and consists of the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. New alveoli continue to form until the age of eight years.
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]
Alveoli are the spherical outcroppings of the respiratory bronchioles. Pulmonary surfactant is a surface-active complex of phospholipids and proteins formed by type II alveolar cells . [ 1 ] The proteins and lipids that make up the surfactant have both hydrophilic and hydrophobic regions.