Select a Community
Are you sure you want to trigger topic in your Anconeus AI algorithm?
You are done for today with this topic.
Would you like to start learning session with this topic items scheduled for future?
Squamous cell proliferation
2%
4/167
Sweeping of debris out of the alveoli by ciliated cells
3/167
Excess mucus production by goblet cells
1%
2/167
Proliferation of surfactant-secreting cells
88%
147/167
Proliferation of club cells
5%
8/167
Select Answer to see Preferred Response
Type II pneumocytes are cuboidal, surfactant-secreting cells that are responsible for the regeneration of alveolar lining following injury. Gas exchange in the lung takes place primarily in the alveoli. Type I pneumocytes are squamous cells that line the alveoli, comprising 97% of alveolar surfaces. Type II pneumocytes are cuboidal cells that secrete pulmonary surfactant, decreasing alveolar surface tension and preventing airway collapse. Type II pneumocytes proliferate following lung damage to form new type I and type II pneumocytes. (See Illustration A) Sanguil and Fargo describe the role of type I and type II pneumocytes in the pathophysiology of ARDS. In ARDS, the release of inflammatory mediators within the lung results in the destruction of the type I and type II cells, compromising the integrity of the alveolar lining and leading to decreased surfactant release. Damage to the surrounding vasculature with vessel leakage also occurs, resulting in pulmonary edema. After the insult, type II cells proliferate, reconstituting the alveolar lining. The reconstitution of the alveolar lining is essential for the removal of fluid and debris from the alveoli and return of lung function. Castranova et al. review the structure and function of alveolar type II pneumocytes. While type II cells cover less than 5% of the alveolar surface, they actually comprise 60% of all alveolar epithelial cells. In addition to forming and secreting surfactant and regenerating alveolar epithelium, type II pneumocytes also play an important role in transepithelial fluid movement and toxin metabolism within the lung. Illustration A shows type I pneumocytes and type II pneumocytes in the respiratory epithelium. Illustration B shows the branching of a lobular bronchiole into terminal and respiratory bronchioles. Incorrect Answers: Answer 1: Type I pneumocytes are squamous cells that comprise the majority of alveolar surfaces but do not proliferate following alveolar injury. Answer 2: Alveolar cells are non-ciliated. Ciliated cells extend to the end of terminal bronchioles (see Illustration B). Answer 3: Mucus-producing goblet cells are not present in the alveoli. Goblet cells extend to the end of bronchi where lobular bronchioles branch (see Illustration B). Answer 5: Club cells (formerly Clara cells) act as reserve cells and do not proliferate following alveolar injury.
3.8
(5)
Please Login to add comment