Do Alveolar Macrophages Secrete Pulmonary Surfactant?

Are there macrophages in the lungs?

In the lung, there are two distinct macrophage populations: alveolar macrophages, which are in close contact with the type I and II epithelial cells of alveoli (1); and interstitial macrophages, which reside in the parenchyma between the microvascular endothelium and alveolar epithelium (2)..

Where are macrophages found?

The macrophages occur especially in the lungs, liver, spleen, and lymph nodes, where their function is to free the airways, blood, and lymph of bacteria and other particles. Macrophages also are found in all tissues as wandering amoeboid cells, and the monocyte, a precursor of the macrophage, is found in the blood.

What is alveolar surfactant?

Alveolar surfactant is a remarkable and highly active surface material composed of lipids and proteins that are present in the fluid lining the alveolar surface of the lungs (Griese, 1999). It has several distinct features, and is carefully regulated under a range of normal physiological conditions throughout life.

What do alveolar macrophages secrete?

To prevent uncontrolled inflammation in the lower respiratory tract, alveolar macrophages secrete nitric oxide, prostaglandins, interleukin-4 and -10(IL-4, IL-10), and transforming growth factor-β (TGF-β).

What is the function of an alveolar macrophage?

Alveolar macrophages are mononuclear phagocytes found in the alveoli of the lungs. They ingest small inhaled particles resulting in the degradation, clearance and presentation of the antigen to adaptive immune cells.

What are the 3 types of alveolar cells?

Each alveolus consists of three types of cell populations:Type 1 pneumocytes.Type 2 pneumocytes.Alveolar macrophages.

What are alveolar macrophages called?

Alveolar macrophages (AM) also known as dust cells are a type of white blood cells. The immune system is divided into the cellular and humoral components. Alveolar macrophages are the first line of defense against invading respiratory pathogens.

Do alveoli secrete surfactant?

Pulmonary surfactant is a mixture of lipids and proteins which is secreted into the alveolar space by epithelial type II cells. The main function of surfactant is to lower the surface tension at the air/liquid interface within the alveoli of the lung.

Which alveolar cells produce pulmonary surfactant?

Pulmonary surfactant is produced by alveolar type II cells and is required for lung function after birth. Pulmonary surfactant is composed of lipids and four lipid-associated proteins, SP-A, SPB, SP-C, and SP-D, that regulate surfactant function, structure, metabolism, and innate host defense.

Is soap a surfactant?

Soaps and detergents are made from long molecules that contain a head and tail. These molecules are called surfactants; the diagram below represents a surfactant molecule. The head of the molecule is attracted to water (hydrophilic) and the tail is attracted to grease and dirt (hydrophobic).

How do you increase pulmonary surfactant?

Purines, such as adenosine triphosphate are potent stimulators of surfactant secretion and may be important for its secretion at birth. Mechanical stretch such as lung distension and hyperventilation, have also been found to be involved in stimulating surfactant secretion.

What are Type 1 alveolar cells?

Type I alveolar cells are squamous extremely thin cells involved in the process of gas exchange between the alveoli and blood. Type II alveolar cells are involved in the secretion of surfactant proteins.

What happens if there is no surfactant?

Without normal surfactant, the tissue surrounding the air sacs in the lungs (the alveoli) sticks together (because of a force called surface tension) after exhalation, causing the alveoli to collapse.

Where is lung surfactant?

Pulmonary surfactant is a complex and highly surface active material composed of lipids and proteins which is found in the fluid lining the alveolar surface of the lungs.

What is the role of pulmonary surfactant?

It is established that pulmonary surfactant reduces surface tension at the air–water interface in the alveoli, thereby preventing collapse of these structures at end-expiration. In this manner, surfactant reduces the work associated with breathing.