How do type 1 and type 2 pneumocytes in the alveoli differ?
Type 1 pneumocytes are alveolar cells that line the alveolar surface. Type 2 pneumocytes are alveolar cells that secrete surfactant proteins to reduce surface tension. Type 1 pneumocytes are flat and thin. Type 2 pneumocytes are cubic in shape.
What are 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.
What are the functions of Pneumocyte 1 and Pneumocyte II?
Moreover, functionally, type 1 pneumocytes are responsible for the process of gas exchange between alveoli and capillaries, while type 2 pneumocytes are responsible for the secretion of pulmonary surfactants in order to reduce surface tension. So, this is the key difference between type 1 and type 2 pneumocytes.
What are the type I and type II 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 is the function of type 1 pneumocytes?
Type I pneumocytes cover 95% of the internal surface of each alveolus. These cells are thin and squamous, ideal for gas exchange. They share a basement membrane with pulmonary capillary endothelium, forming the air-blood barrier where gas exchange occurs.
What are the functions of type 1 and 2 pneumocytes and the alveolar macrophage?
Typically, type 1 alveolar cells comprise the major gas exchange surface of the alveolus and are integral to the maintenance of the permeability barrier function of the alveolar membrane. Type 2 pneumocytes are the progenitors of type 1 cells and are responsible for surfactant production and homeostasis.
Where are type 1 pneumocytes found?
alveolar capillaries
Type I pneumocytes have a continuous basement membrane that is fused with the basement membrane of the endothelial cells of the alveolar capillaries (Fig. 8.31). These capillaries are located directly beneath the alveolar lining cells.
What is the function of type 2 alveolar cells?
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.
What do type 2 pneumocytes do?
Type II pneumocytes are identified as the synthesizing cells of the alveolar surfactant, which has important properties in maintaining alveolar and airway stability. Lung surfactant can reduce the surface tension and prevent alveolar collapse and the airway walls collapse.
What is the function of type I pneumocytes in alveoli?
What do type 1 pneumocytes produce?
The type I cell is responsible for gas exchange and the type II cell synthesizes and secretes surfactant. At birth the lung has no mature alveoli but instead contains approximately 20 million primitive terminal sacs. These sacs are lined by mature alveolar epithelium; they resemble large shallow cups.
What do type 2 pneumocytes produce?
Surfactant and the Type 2 Pneumocyte. 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 are the functions of type III pneumocytes?
The third type of cells (Type 3 pneumocytes) are the macrophages which are responsible for removing foreign bodies be it bacteria, dust, damaged blood cells etc.
What are the 3 types of alveolar cells?
There are three major types of alveolar cell. 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.
Which pneumocytes produce surfactant?
What is the function of type 2 pneumocytes?