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A lobule of the lung enclosed in septa and supplied by a terminal bronchiole that branches into the respiratory bronchioles. 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.
Type I cells, also called type I pneumocytes, or type I alveolar cells, are squamous, thin and flat and form the structure of the alveoli. Type II cells, also called type II pneumocytes or type II alveolar cells, release pulmonary surfactant to lower surface tension, and can also differentiate to replace damaged type I cells. [12] [15]
An acinus (/ ˈ æ s ɪ n ə s /; pl.: ... acinar / ˈ æ s ɪ n ər / or acinous) refers to any cluster of cells that resembles a many ... as is the alveolar sac ...
In humans and other mammals, the anatomy of a typical respiratory system is the respiratory tract.The tract is divided into an upper and a lower respiratory tract.The upper tract includes the nose, nasal cavities, sinuses, pharynx and the part of the larynx above the vocal folds.
Panlobular emphysema, also called panacinar emphysema, affects all of the alveoli in a lobule, and can involve the whole lung or mainly the lower lobes. [ 18 ] [ 24 ] This type of emphysema is associated with alpha-1 antitrypsin deficiency (A1AD or AATD), and Ritalin lung , [ 24 ] and is not related to smoking.
They contain serous acini, a grouping of serous cells that secrete serous fluid, isotonic with blood plasma, that contains enzymes such as alpha-amylase. Serous glands are most common in the parotid gland and lacrimal gland but are also present in the submandibular gland and, to a far lesser extent, the sublingual gland .
This marks the beginning of the terminal respiratory unit called the acinus which includes the respiratory bronchioles, the alveolar ducts, alveolar sacs, and alveoli. [27] An acinus measures up to 10 mm in diameter. [28] A primary pulmonary lobule is the part of the lung distal to the respiratory bronchiole. [29]
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]