where is surfactant produced

What is inadequate surfactant production?

Surfactant production is insufficient due to the immature development of type II pneumocytes, which begin to produce surfactant at approximately 20 weeks gestation . Insufficient surfactant leads to reduced pulmonary compliance and increased surface tension [2,3]. This results in increased risk of alveoli collapse at expiration followed by ...

Does surfactant helps increase alveolar surface tension?

The surfactant lines the alveolar walls over the water film, and then reduces the surface tension and thus the collapsing pressure. Diving deep into this, let’s zoom in and look at a cross-section of the wall of the pulmonary alveoli.

What cells of the alveolar that produces surfactant?

Type ii cells comprise 17% of the cells of the alveolar wall and cover about 5% of the alveolar surface. They produce surfactant, which helps keep the balloon shape from collapsing. Alveoli also contain immune cells called alveolar macrophages. Type 2 Cells Produce Surfactant And Play A Role In Maintenance Of Lung Fluid Balance.

What is the function of surfactant in the respiratory system?

Terms in this set (26)

1. Increase the compliance of lung tissue, facilitating alveolar inflation
2. Reduce the tendency of lung tissue to recoil at any given inflating pressure
3. Helps keep the lungs "dry" by preventing accumulation of fluid (edema) within alveolar airspaces

What is the function of surfactant and where is it produced?

Surfactant is a mixture of fat and proteins made in the lungs. Surfactant coats the alveoli (the air sacs in the lungs where oxygen enters the body). This prevents the alveoli from sticking together when your baby exhales (breathes out).

Which cells produce the 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 surfactant produced in the liver?

The synthesis of surfactant occurs mainly in the lungs. However, SP-A mRNA and protein expression is also found in nonpulmonary sites, such as brain, kidney, and female reproductive tract. SP-A regulates the immune homeostasis in these organs (15, 20, 23, 36, 37).

Do the upper airways produce surfactant?

Surfactant is not restricted to the alveolar compartment; it also reaches terminal conducting airways and is present in upper airway secretions.

What are the 4 types of surfactants?

Types of SurfactantsAnionic Surfactants. Anionic surfactants have a negative charge on their hydrophilic end. ... Nonionic Surfactants. Nonionic surfactants are neutral, they do not have any charge on their hydrophilic end. ... Cationic Surfactants. ... Amphoteric Surfactants.

Is there surfactant on alveoli?

Surfactant is released from the lung cells and spreads across the tissue that surrounds alveoli. This substance lowers surface tension, which keeps the alveoli from collapsing after exhalation and makes breathing easy.

What stimulates surfactant production?

These studies suggest that labor stimulates both the synthesis and secretion of surfactant in the immediate postnatal period and thus may be an important factor in the prevention of the respiratory distress syndrome of the newborn.

What is the function of surfactant?

Function. The main functions of surfactant are as follows: (1) lowering surface tension at the air–liquid interface and thus preventing alveolar collapse at end-expiration, (2) interacting with and subsequent killing of pathogens or preventing their dissemination, and (3) modulating immune responses.

What is the role of pulmonary surfactants?

Human pulmonary surfactant (PS) is an endogenous lipoprotein complex produced naturally in the lungs. PS forms a layer on the alveolar epithelium and is responsible in reducing surface tension at the air-fluid interface on the alveolar surface (Agassandian and Mallampalli, 2013).

Which cells produce surfactant quizlet?

Surfactant is a complex substance containing phospholipids and a number of apoproteins. This fluid is produced by the Type II alveolar cells, and lines the alveoli and smallest bronchioles.

What causes surfactant deficiency?

Genetic surfactant dysfunction disorders are caused by DNA sequence variants in genes encoding proteins critical for the production and function of pulmonary surfactant.

Do adults have surfactant in lungs?

Pulmonary surfactant is synthesized and secreted by alveolar type II cells and constitutes an important component of the alveolar lining fluid. It comprises a unique mixture of phospholipids and surfactant-specific proteins.

Which cells produce surfactant quizlet?

Surfactant is a complex substance containing phospholipids and a number of apoproteins. This fluid is produced by the Type II alveolar cells, and lines the alveoli and smallest bronchioles.

What are alveolar type 2 cells?

Alveolar type II (ATII) cells play a key role as part of the distal lung epithelium, including roles in the innate immune response and as self-renewing progenitors to replace alveolar type I (ATI) cells during regeneration of the alveolar epithelium.

What is the function of type 2 pneumocytes?

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.

Where are Clara cells located?

The Clara cells are a group of cells, sometimes called "nonciliated bronchiolar secretory cells", found in the bronchiolar epithelium of mammals including man, and in the upper airways of some species such as mice.

Where are surfactants produced?

The human body produces diverse surfactants. Pulmonary surfactant is produced in the lungs in order to facilitate breathing by increasing total lung capacity, and lung compliance. In respiratory distress syndrome or RDS, surfactant replacement therapy helps patients have normal respiration by using pharmaceutical forms of the surfactants. One example of pharmaceutical pulmonary surfactants is Survanta ( beractant) or its generic form Beraksurf produced by Abbvie and Tekzima respectively. Bile salts, a surfactant produced in the liver, play an important role in digestion.

When was surfactant invented?

The word "surfactant" is a blend of surface-active agent, coined c. 1950.

What is the structure of surfactant phases in water?

Structure of surfactant phases in water. In the bulk aqueous phase, surfactants form aggregates, such as micelles, where the hydrophobic tails form the core of the aggregate and the hydrophilic heads are in contact with the surrounding liquid.

Why do surfactant ions remain in oil?

Schematic diagram of a micelle – the lipophilic tails of the surfactant ions remain inside the oil because they interact more strongly with oil than with water. The polar "heads" of the surfactant molecules coating the micelle interact more strongly with water, so they form a hydrophilic outer layer that forms a barrier between micelles. This inhibits the oil droplets, the hydrophobic cores of micelles, from merging into fewer, larger droplets ("emulsion breaking") of the micelle. The compounds that coat a micelle are typically amphiphilic in nature, meaning that micelles may be stable either as droplets of aprotic solvents such as oil in water, or as protic solvents such as water in oil. When the droplet is aprotic it is sometimes known as a reverse micelle.

What is the purpose of surfactant?

Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, or dispersants .

Where can anionic surfactants be found?

Anionic surfactants can be found in soils as the result of sewage sludge application, wastewater irrigation, and remediation processes. Relatively high concentrations of surfactants together with multimetals can represent an environmental risk. At low concentrations, surfactant application is unlikely to have a significant effect on trace metal mobility.

How many tails does a surfactant have?

Surfactant molecules have either one tail or two; those with two tails are said to be double-chained .

How is surfactant produced?

Surfactant production increases with increasing gestational age in the normal neonate. The lack of lung maturity and associated surfactant deficiency cause respiratory distress syndrome (RDS). Pulmonary edema, alveolar capillary leak, pulmonary hemorrhage, and the presence of meconium in the airways can inactivate surfactant. Decreased surfactant activity results in alveolar collapse, atelectasis, ventilation-perfusion abnormalities, decreased lung compliance, resulting in a decreased ventilation and pulmonary hypertension leading to respiratory failure. Surfactant maintains lung volumes and enhances the clearance of lung liquid. Surfactant replacement decreases the incidence of air leak and mortality that accompany RDS.

What is surfactant in water?

Surfactants, or surface-active agents, are amphiphilic molecules. Their heads are polar, or hydrophilic, and their tails hydrophobic. They are soluble in both organic solvent and water. The surfactant reduces the surface tension of water by adsorbing at the liquid–gas interface. They also reduce the interfacial tension between oil and water by adsorbing at the liquid–liquid interface. CPE is the first extraction method in which a surfactant has been used. A surfactant could serve as an emulsifier to enhance the dispersion of the water-immiscible phase into the aqueous phase. Saraji and Bidgoli294 developed an efficient surfactant-assisted DLLME (SA-DLLME) for determination of phenylurea herbicides in water samples. Yamini et al. 238 reported another application of SA-DLLME for the extraction and determination of chlorophenols as model compounds in environmental water samples. The surfactants used are environmentally friendly and cost-effective to such an extent that the amounts used for effective extraction schemes are minimal compared with the amounts of organic solvents used in conventional DLLME. A list of surfactants as disperser used in DLLME along with representative concentrated analytes is given in Table 2.

What is the solubility of surfactants?

Surfactants are also classified depending on their solubility, such as hydrophilic surfactants that are soluble in water or hydrophobic (lipophilic) surfactants that are soluble in lipids. Ionic surfactants are generally hydrophilic surfactants, but nonionic surfactants can be either hydrophilic or lipophilic, depending on the balance of the hydrophilic group and lipophilic group. In other words, the solubility of nonionic surfactants depends on the balance between the hydrophilic group's capacity of attracting water and the lipophilic group's capacity of attracting oil. Hydrophilic-lipophilic balance (HLB) is an indicator that quantifies this relative balance. HLB was first proposed by Griffin 1 and currently several formulas to calculate HLB have been reported. 2,3 Since HLB indicates the characteristics of nonionic surfactants, it is commonly used as an indicator for choosing a surfactant for specific applications, such as emulsifiers or cleansers, which are both mentioned later in this chapter ( Fig. 15.2 ). However, since HLB is merely an indicator based on experience, it can be used as a reference to choose a surfactant for an application but this is not enough in formulation development and that can lead to many challenges. Knowing the characteristics of surfactants efficiently and quickly is vital in formulation development. In addition to the HLB, there are two indicators that subjectively show these characteristics: the cloud point for nonionic surfactants and the Krafft point for ionic surfactants.

How to remove DNAPLs from aquifers?

SEAR-solubilization techniques are commonly used to remove DNAPLs from aquifers. DNAPL-impacted sites can contain a number of components such as TCE, PCE; 1,1,1-trichloroethane, and other chlorinated solvents with densities that range from 1.1 to 1.6 g/ml. If these oils are displaced from the porous media as a “plume of dense oil” they tend to sink deeper into the aquifer, making their removal more difficult. Similar to hard surface cleaners, the SEAR-solubilization approach seeks to solubilize organic contaminants into the hydrophobic core of micelles, thereby increasing the apparent “aqueous solubility” of the contaminant [ 16, 17, 140, 141 ]. The process of oil removal in SEAR-solubilization technology is simple in principle: the surfactant formulation is continuously injected into the aquifer, then the surfactant micelles that encounter an NAPL–water interface solubilize the NAPL, and incorporate the solubilized NAPL into the aqueous phase. The surfactant solution loaded with NAPL is continuously extracted from the aquifer, the NAPL is then removed using different separation processes above ground, and the surfactant solution is then re-formulated and re-injected into the aquifer. This semi-closed continuous loop is monitored by measuring concentration of NAPL in the extracted surfactant solution to evaluate the need to change flow configuration or stop the surfactant flush. After the surfactant flush is completed, water is flushed through the system to remove any residual surfactant from the aquifer and re-equilibrate the system. The concentration of NAPL in the extracted water is closely monitored to determine the reduction of this concentration with respect to the initial value. The success of a remediation technology is evaluated in terms of the reduction of the aqueous NAPL concentration and the fraction of total NAPL removed (this is called source reduction). Also, the mass balance of the surfactant is an important parameter to determine the amount of surfactant retained in the aquifer. SEAR solubilization uses relatively large quantities of surfactants, typically the surfactant concentration ranges between 2 and 8% of anionic surfactants (e.g. sodium dihexyl sulfosuccinate), and/or nonionic surfactants (e.g. alkyl polyethylene glycols), and medium-chain alcohols (isopropanol, pentanol, etc.) [ 143, 144 ].

What is nonionic surfactant?

Nonionic surfactants are surfactants that do not dissociate into ions in aqueous solutions, and they are subclassified depending on the type of their hydrophilic group ( Fig. 15.1 ). Common hydrophilic groups of ionic surfactants are carboxylate (–COO − ), sulfate (–OSO 3− ), sulfonate (SO 3− ), carboxybetaine (–NR 2 CH 2 COO − ), ...

What is the name of the group of molecules that have affinity to water?

The surfactant molecules also have a functional group called the hydrophilic group that has affinity to water. This kind of structure with two opposing functions is called an amphiphilic structure. Surfactants are classified into ionic surfactants and nonionic surfactants.

Why are surfactants biobased?

Biobased surfactants derived from fatty acids and neutral lipids continue to grow in their employment and interest, due mainly to their good surfactant properties, biodegradability, biocompatibility, and their potential replacement of fossil fuel-derived surfactants, which is of interest to many consumers because of the linkage of fossil fuels to climate change. Currently, fossil fuel-derived feedstocks are less expensive than renewable resources. However, this trend will likely reverse in the future, thereby further enhancing long-term prospects of biobased surfactants. The versatility of chemistries available to convert fatty acids and other biobased feedstocks into viable and useful surfactants will be leveraged to prepare new and valuable biobased surfactants in the years to come, with increasing use of green manufacturing principles.

Where is surfactant formed?

It seems likely that surfactant is both formed in and liberated from the alveolar epithelial type II cell ( page 18 ). Pulmonary surfactant is formed relatively late in the process of maturation of the fetus. The concentration of lecithin in the amniotic fluid reflects the quantity in the alveoli and it increases sharply late in gestation. In contrast, the quantity of sphingomyelin remains fairly constant, and the lecithin/sphingomyelin (L/S) ratio in the amniotic fluid has been used as an indication of pulmonary maturity.

What is the most abundant surfactant?

The most abundant component of surfactant is a disaturated phosphatidylcholine, dipalmitoyl lecithin, which accounts for about 40% of lung surface-active material (Clements, 1973 ).

When is surfactant detected in amniotic fluid?

Surfactant is not normally detected in amniotic fluid in large quantities until after 35 weeks gestation, at a time when large amounts of saturated phosphatidylcholine are present in the fetal lung tissue.

How is surfactant removed from soil?

The solvent/surfactant and released contaminants are then separated from the soil. The soil is then washed or aerated to remove the surfactant/solvent. The surfactant/solvent is then filtered for fine particles and treated to remove the contaminants. This technique is quite expensive and is not often used.

When is surfactant detected in the lungs?

Surfactant is first detectable in the fetal lung at 20-24 weeks of gestation but the concentration increases rapidly after the 30th week.

Is surfactant a protein?

In addition to phospholipids, there is evidence that surfactant contains a unique protein and is probably secreted as a lipoprotein ( Clements, 1973; Farrell and Avery, 1975 ). However, the specific association of protein with surfactant has been questioned by some workers ( Scarpelli and colleagues, 1970 ).

What is a surfactant?

Tap card to see definition 👆. Surfactant is a complex substance containing phospholipids and a number of apoproteins. This fluid is produced by the Type II alveolar cells, and lines the alveoli and smallest bronchioles. Surfactant reduces surface tension throughout the lung.

Why is surfactant important?

Surfactant reduces surface tension throughout the lung. It is also important because it stabilizes the alveoli.That is, at a constant surface tension, small alveoli will generate bigger pressures within them than will large alveoli.

When does surfactant start to form?

Surfactant production in humans begins in type II cells during the alveolar sac stage of lung development. Lamellar bodies appear in the cytoplasm at about 20 weeks gestation. These lamellar bodies are secreted by exocytosis into the alveolar lining fluid, where the surfactant forms a meshwork of tubular myelin Full term infants are estimated to have an alveolar storage pool of approximately 100 mg/kg of surfactant, while preterm infants have an estimated 4–5 mg/kg at birth.

What makes up 10% of surfactant?

Proteins. Proteins make up the remaining 10% of the surfactant. Half of this 10% is plasma proteins but the rest is formed by the apolipoproteins, surfactant proteins SP-A, SP-B, SP-C, and SP-D. The apolipoproteins are produced by the secretory pathway in type II cells.

How long does alveolar surfactant last?

Alveolar surfactant has a half-life of 5 to 10 hours once secreted. It can be both broken down by macrophages and/or reabsorbed into the lamellar structures of type II pneumocytes. Up to 90% of surfactant DPPC (dipalmitoylphosphatidylcholine) is recycled from the alveolar space back into the type II pneumocyte. This process is believed to occur through SP-A stimulating receptor-mediated, clathrin dependent endocytosis. The other 10% is taken up by alveolar macrophages and digested.

How does alveolar size regulation affect the rate of expansion?

Alveolar size regulation. As the alveoli increase in size, the surfactant becomes more spread out over the surface of the liquid. This increases surface tension effectively slowing the rate of expansion of the alveoli.

What is the surfactant of alveoli?

Pulmonary surfactant. Alveoli are the spherical outcroppings of the respiratory bronchioles. Pulmonary surfactant is a surface-active lipoprotein complex (phospholipoprotein) formed by type II alveolar cells. The proteins and lipids that make up the surfactant have both hydrophilic and hydrophobic regions.

How does SP affect surfactant adsorption?

SP molecules contribute to increasing the surfactant interface adsorption kinetics, when the concentration is below the saturation level. They also make weak bonds with the surfactant molecules at the interface and hold them longer there when the interface is compressed. Therefore, during ventilation, surface tension is usually lower than at equilibrium. Therefore, the surface tension varies according to the volume of air in the lungs, which protects them from atelectasis at low volumes and tissue damage at high volume levels.

How does SP protein work?

Each SP protein has distinct functions, which act synergistically to keep an interface rich in DPPC during lung's expansion and contraction. Changes in the surfactant mixture composition alter the pressure and temperature conditions for phase changes and the phospholipids' crystal shape as well. Only the liquid phase can freely spread on the surface to form a monolayer. Nevertheless, it has been observed that if a lung region is abruptly expanded the floating crystals crack like " icebergs ". Then the SP proteins selectively attract more DPPC to the interface than other phospholipids or cholesterol, whose surfactant properties are worse than DPPC's. The SP also fastens the DPPC on the interface to prevent the DPPC from being squeezed out when the surface area decreases This also reduces the interface compressibility.

Overview

In biology

The human body produces diverse surfactants. Pulmonary surfactant is produced in the lungs in order to facilitate breathing by increasing total lung capacity, and lung compliance. In respiratory distress syndrome or RDS, surfactant replacement therapy helps patients have normal respiration by using pharmaceutical forms of the surfactants. One example of a pharmaceutical pulmonary surfactant is Survanta (beractant) or its generic form Beraksurf, produced by Abbvie and Tekzim…

Composition and structure

Safety and environmental risks

Applications

Classification

See also

External links