What is pulmonary 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.

Surfactant is an agent that decreases the surface tension between two media. The surface tension between gaseous-aqueous interphase in the lungs is decreased by the presence of a thin layer of fluid known as pulmonary surfactant. It is essential for efficient exchange of gases and for maintaining the structural integrity of alveoli. Surfactant is a secretory product, composed of lipids and proteins. The lipid and protein components are synthesized separately and are packaged into the lamellar bodies in the AT-II cells. Lamellar bodies are the main organelle for the synthesis and metabolism of surfactants.

What is pulmonary surfactant

Pulmonary surfactant is a surface-active complex of phospholipids and proteins formed by type II alveolar cells. By adsorbing to the air-water interface of alveoli , with hydrophilic head groups in the water and the hydrophobic tails facing towards the air, the main lipid component of surfactant, dipalmitoylphosphatidylcholine DPPC , reduces surface tension. As a medication, pulmonary surfactant is on the WHO Model List of Essential Medicines , the most important medications needed in a basic health system. Alveoli can be compared to gas in water, as the alveoli are wet and surround a central air space. The surface tension acts at the air-water interface and tends to make the bubble smaller by decreasing the surface area of the interface. Compliance is the ability of lungs and thorax to expand. Lung compliance is defined as the volume change per unit of pressure change across the lung. This difference in inflation and deflation volumes at a given pressure is called hysteresis and is due to the air-water surface tension that occurs at the beginning of inflation. However, surfactant decreases the alveolar surface tension , as seen in cases of premature infants with infant respiratory distress syndrome. Pulmonary surfactant thus greatly reduces surface tension , increasing compliance allowing the lung to inflate much more easily, thereby reducing the work of breathing. It reduces the pressure difference needed to allow the lung to inflate. The lung's compliance, and ventilation decrease when lung tissue becomes diseased and fibrotic.

Wheater's functional histology : a text and colour atlas. Retrieved May 10, In other projects.

.

Federal government websites often end in. Before sharing sensitive information, make sure you're on a federal government site. The site is secure. NCBI Bookshelf. Hina Khawar ; Komal Marwaha. Authors Hina Khawar ; Komal Marwaha 1.

What is pulmonary surfactant

Lung surfactant is a complex with a unique phospholipid and protein composition. Its specific function is to reduce surface tension at the pulmonary air-liquid interface. The underlying Young-Laplace equation, applying to the surface of any geometrical structure, is the more important the smaller its radii are. It therefore applies to the alveoli and bronchioli of mature lungs, as well as to the tubules and saccules of immature lungs. Maturation of the surfactant system is not essentially due to increased synthesis but to decreased turnover of specific components. As there is no need for a surface-associated surfactant reservoir, SP-C is absent in birds as well. Airflow is lowest and particle sedimentation highest in the extrapulmonary air-sacs, rather than in the gas-exchange area. Consequently, SP-A and -D for particle opsonization are absent in bird surfactant. In essence, comparative analysis is consistent with the concept that surfactant is adapted to the physiologic needs of a given vertebrate species at a given developmental stage. Keywords: Airways surfactant; Bird surfactant; Mammalian surfactant; Phospholipid molecular species; Surfactant variability; Young—Laplace-equation.

Emoji gg

This also explains why the compliance is greater during expiration than during inspiration. Therefore, during ventilation, surface tension is usually lower than at equilibrium. The DPPC is the strongest surfactant molecule in the pulmonary surfactant mixture. A pathophysiological role for surfactant was first appreciated in premature infants with respiratory distress syndrome and hyaline membrane disease, a condition which is nowadays routinely treated with exogenous surfactant replacement. Annals of Anatomy. Surfactant degradation or inactivation may contribute to enhanced susceptibility to lung inflammation and infection. However the significance of his discovery was not understood by the scientific and medical community at that time. The surface tension acts at the air-water interface and tends to make the bubble smaller by decreasing the surface area of the interface. The fast adsorption velocity is necessary to maintain the integrity of the gas exchange region of the lungs. Lamellar bodies are the main organelle for the synthesis and metabolism of surfactants. Compliance is the ability of lungs and thorax to expand. Contents move to sidebar hide.

Federal government websites often end in.

These proteins can bind to sugars on the surface of pathogens and thereby opsonize them for uptake by phagocytes. Experimental Lung Research. Categories : Respiratory physiology Integral membrane proteins Surfactants Pulmonary function testing Lipopeptides. Journal of Applied Physiology. Ex-situ measurements of surface tension and interfacial rheology can help to understand the functionality of pulmonary surfactants. The lipid and protein components are synthesized separately and are packaged into the lamellar bodies in the AT-II cells. Lamellar bodies are the main organelle for the synthesis and metabolism of surfactants. Alveoli can be compared to gas in water, as the alveoli are wet and surround a central air space. Tools Tools. Hidden categories: All articles lacking reliable references Articles lacking reliable references from May Wikipedia articles needing page number citations from May CS1 Vietnamese-language sources vi CS1 maint: location missing publisher CS1 German-language sources de Articles with short description Short description is different from Wikidata All articles with unsourced statements Articles with unsourced statements from May The apolipoproteins are produced by the secretory pathway in type II cells.