What is the difference between type1 and type 2 alveolar cells?
The type I cell is a complex branched cell with multiple cytoplasmic plates that are greatly attenuated and relatively devoid of organelles; these plates represent the gas exchange surface in the alveolus. On the other hand, the type II cell acts as the “caretaker” of the alveolar compartment.
What are type 2 alveolar cells?
Type II cells are defenders of the alveoli by secreting surfactant, keeping the alveolar space relatively free from fluid, serving as progenitor cells to repopulate the epithelium after injury, and providing important components of the innate immune system.
What is the function of type 1 alveolar cells?
Pulmonary alveolar type I (AT1) cells cover more than 95% of alveolar surface and are essential for the air–blood barrier function of lungs. AT1 cells have been shown to retain developmental plasticity during alveolar regeneration. However, the development and heterogeneity of AT1 cells remain largely unknown.
Are type 1 cells simple squamous?
Alveolar Epithelial Cells Most of the alveolar surface is covered by simple squamous cells known as type I pneumocytes (Figure 1-9). These cells have a small nucleus with highly branched cytoplasmic processes covering 4000 to 5000 µm2. The cytoplasm contains sparse organelles.
Where are type 2 alveolar cells found?
Two types are pneumocytes or pneumonocytes known as type I and type II cells found in the alveolar wall, and a large phagocytic cell known as an alveolar macrophage that moves about in the lumens of the alveoli, and in the connective tissue between them.
What are the functions of the type 1 and 2 pneumocytes?
Pneumocyte: One of the cells lining the alveoli (the air sacs) in the lung. The alveoli are, in fact, lined with two types of cells termed the type 1 and type 2 pneumocytes: Type 1 pneumocyte: The cell responsible for the gas (oxygen and carbon dioxide) exchange that takes place in the alveoli.
Are there more Type 1 or 2 pneumocytes?
The type I pneumocytes form part of the barrier across which gas exchange occurs. They can be identified as thin, squamous cells whose most obvious feature is their nuclei. Type II pneumocytes are larger, cuboidal cells and occur more diffusely than type I cells.
What do type 2 alveolar cells do?
Four major functions have been attributed to alveolar type II cells: (1) synthesis and secretion of surfactant; (2) xenobiotic metabolism; (3) transepithelial movement of water; and (4) regeneration of the alveolar epithelium following lung injury.
Why are type two alveolar cells important?
Type II cells are the progenitor cells for the alveolar epithelium and are responsible for reforming the alveolar epithelium after damage to the very sensitive type I cells. Type II cells also trans- port sodium and fluid from the apical surface into the interstitium and play an important role in innate immunity.
What do type 2 pneumocytes produce?
The main function of type 2 pneumocytes is the production of pulmonary surfactant: Surfactant is a complex mixture of phospholipids (mainly dipalmitoyl phosphatidylcholine), carbohydrates (glycosaminoglycans) and proteins (including SP-A, SP-B, SP-C and SP-D)
What is structural characteristic of the alveoli?
Structure Alveoli are tiny balloon shaped structures and are the smallest passageway in the respiratory system. The alveoli are only one cell thick, allowing the relatively easy passage of oxygen and carbon dioxide (CO2) between the alveoli and blood vessels called capillaries. One cubic millimeter of lung tissue contains around 170 alveoli.
Where are alveoli found?
Alveoli are the functional units of the lungs that permit gas exchange between the air in the lungs and the blood in the capillaries of the lungs. Alveoli are found in small clusters called alveolar sacs at the end of the terminal bronchiole.
What are the features of the alveoli?
Features of the alveoli. The alveoli are adapted to make gas exchange in lungs happen easily and efficiently. Here are some features of the alveoli that allow this: they give the lungs a really big surface area. they have moist, thin walls (just one cell thick) they have a lot of tiny blood vessels called capillaries.