What is surfactant and how does it affect of the lungs?
Surfactant reduces the surface tension of fluid in the lungs and helps make the small air sacs in the lungs (alveoli) more stable. This keeps them from collapsing when an individual exhales. In preparation for breathing air, fetuses begin making surfactant while still in the womb.
What is the purpose of surfactant in the lungs?
Surfactant prevents the lungs from collapsing by reducing surface tension throughout the lungs. Surface tension is the main force that is present within the alveoli of the lungs. Without surfactant, the surface tension present in the lungs causes the alveoli to stick together during expiration, which causes both lungs to collapse.
What is the role of surfactants in lungs?
The Role of Surfactant in Lung Disease and Host Defense against Pulmonary Infections
- Abstract. Pulmonary surfactant is essential for life as it lines the alveoli to lower surface tension, thereby preventing atelectasis during breathing.
- Surfactant Composition and Function. ...
- Pulmonary Disorders Related to Surfactant Dysfunction or Deficiency. ...
- Antimicrobial Function. ...
- Conclusions. ...
- Summary. ...
- Footnotes. ...
- References. ...
What is the function of the pulmonary surfactant?
Pulmonary surfactant is a mixture of lipids and proteins which is secreted by the epithelial type II cells into the alveolar space. Its main function is to reduce the surface tension at the air/liquid interface in the lung.
How does pulmonary surfactant reduce surface tension?
Pulmonary surfactant works to reduce the surface tension by replacing some of the water molecules at the alveolar surface. The attractive forces be...
What would happen to your lungs without surfactant?
Without surfactant in the lungs, the alveolar tissue would stick together and collapse as a human breathes out. This would cause the lungs to colla...
Where is pulmonary surfactant found?
Pulmonary surfactant is found lining the alveolar surfaces of the lungs. This is where the air and fluid exchange occurs in the lungs.
What is the purpose of a surfactant?
The purpose of a surfactant in the lungs is to reduce surface tension at the alveolar tissue. This is where the exchange between liquids and air oc...
What produces lung surfactant?
The alveolar type II cells of the lung product the surfactant that is present in the lungs over the alveolar tissues.
What is the function of lung surfactant?
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.
What percentage of surfactant proteins are phosphatidylglycerol?
Anionic phosphatidylglycerol and cholesterol are about 10% each, whereas surfactant proteins SP-A to -D comprise 2-5%. Maturation of the surfactant system is not essentially due to increased synthesis but to decreased turnover of specific components.
Is particle opsonization absent in bird surfactant?
Consequently, SP-A and -D for particle opsonization are absent in bird surfactant.
What is the purpose of surfactant in the lungs?
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.
What is pulmonary surfactant?
Pulmonary surfactants and their role in pathophysiology of lung disorders. 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. The pulmonary surfactant is produced by the ...
What is a surfactant?
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. The pulmonary surfactant is produced by the alveolar type-II (AT-II) c ….
Which organelle is responsible for the synthesis and metabolism of surfactants?
Lamellar bodies are the main organelle for the synthesis and metabolism of surfactants. The synthesis, secretion and recycling of the surfactant lipids and proteins is regulated by complex genetic and metabolic mechanisms.
What is the agent that decreases the surface tension between two media?
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. The pulmonary surfactant is produced by the alveolar type-II (AT-II) cells of the lungs.
How do surfactants work in the lungs?
The surfactant is produced by specialized AT-II cells in the alveoli and works by decreasing the surface tension in the alveoli. This prevents the alveoli from collapsing during exhalation with the loss of thoracic pressure and for respiration to continue seamlessly. Many medical disorders such as RDS affect the function of surfactants due to the lack of sufficient surfactant being produced by the alveolar cells. This causes many unsettling respiratory symptoms in patients and can even lead to death due to lack of respiration without treatment.
What Produces Surfactant in the Lungs?
There are specialized cells in the lungs that produce the pulmonary surfactant. These are the alveolar type-II (AT-II) cells of the lungs. As the alveoli are the places where gas exchange takes place, this is an ideal location for the surfactant to be produced.
How does surfactant affect the alveoli?
This allows for a faster decrease in surface tension of the alveoli thus allowing more air to enter the lungs during inhalation.
What is the role of the lungs in the body?
The lungs are responsible for the transfer of oxygen into the blood as a person breathes inwards and for the transfer of carbon dioxide and any other gases out of the blood as a person exhales. The alveoli are air-filled sacs in the lungs that allow for this exchange to occur. They are lined with tiny capillaries that carry the gases to and away from the rest of the body. When a person exhales, the loss of pressure in the thoracic cavity can cause the alveoli to collapse. The pulmonary surfactant is a special fluid released by cells in the lungs that prevents this collapse from occurring on exhalation. Respiratory Distress Syndrome is a disorder in which the lack of enough surfactant in immature lungs causes babies to breathe poorly and they may even stop breathing.
What would happen if you didn't have surfactant in your lungs?
Without surfactant in the lungs, the alveolar tissue would stick together and collapse as a human breathes out . This would cause the lungs to collapse.
What is surfactant dysfunction?
In adult patients, a similar disorder can occur known as surfactant dysfunction disorder . It is caused by mutations in genes that are responsible for the production of surfactants. In any patient with a lack of surfactant, it is very important to monitor their oxygen and carbon dioxide, even with treatment, to ensure the treatment is working.
Where does oxygen and carbon dioxide exchange occur?
The gas exchange of oxygen and carbon dioxide occurs in the alveoli of the lungs. Alveoli are lined on their outer surface with tiny capillaries that carry blood to and away from the alveoli. Carbon dioxide moves from these capillaries bringing blood to the alveoli from the rest of the body to move out of the capillaries into the alveoli and out of the lungs and mouth during exhalation. During inhalation, oxygen moves from the nose and mouth into the lungs and into alveoli, where it then diffuses into the capillaries which carry the blood to the rest of the body to oxygenate the tissues of the body. During exhalation, the thoracic cavity undergoes a significant decrease in pressure. This can cause the tiny air-filled sacs called alveoli to collapse and the walls of the sacs to stick to each other. The surfactant is what prevents this from happening and keeps alveoli intact and inflated ready to accept oxygenated air with the next inhale.
What is surfactant in the lung?
Pulmonary surfactant is a lipoprotein complex that lines the alveoli and decreases the surface tension to prevent lung atelectasis. Surfactant deficiency is a documented cause of neonatal respiratory distress syndrome (NRDS), a major cause of morbidity and mortality in premature infants. Therapeutic indications for surfactant replacement therapy include neonates with clinical and radiographic evidence of respiratory distress syndrome (RDS) and infants who require endotracheal intubation and mechanical ventilation secondary to respiratory failure. Surfactant is prophylactically administered in neonates at risk of developing NRDS. This activity will discuss the biochemical structure of surfactant, its administration, related complications, and the future of surfactant therapy.
Where is pulmonary surfactant produced?
Its production begins around 26 weeks gestation and reaches mature levels at approximately 35 weeks. It is produced in the endoplasmic reticulum (ER) of type two pneumocytes and secreted from the lamellar bodies of type two pneumocytes.[4] Other cells in the lung, namely club or Clara cells, also produce surfactant. This lipoprotein mixture enhances lung compliance and aids in lowering the surface tension of the air-liquid interface within alveolar walls, which will ultimately prevent atelectasis. [1]
How to administer surfactant?
Surfactant is administered in liquid form via an endotracheal tube in a single bolus dose as quickly as the neonate tolerates. Some studies recommend administering all the surfactant at once, while others advocate dividing the bolus into smaller aliquots.
What is the role of pharmacy in surfactant therapy?
The pharmacy will be responsible for ensuring proper preparation of the surfactant, verifying dosing and administration, and serving as a drug information resource to the rest of the team. Only with an interprofessional team approach and open communication can surfactant therapy optimally reduce the morbidity of respiratory distress syndrome in neonates. [Level 5]
What are the components of surfactant?
Surfactant proteins comprise about 10% of the structure and interact extensively with phospholipids. They are SP-A, SP-B, SP-C, and SP-D. The SP-A and SP- D proteins are part of the innate immune response. These proteins coat bacteria and viruses, allowing phagocytosis and destruction by macrophages.[5] SP-A also appears to be a part of a negative feedback mechanism that controls surfactant release from type II alveolar cells. SP-B and SP-C are hydrophobic proteins that control the rate at which surfactant covers the surface of alveoli.
Is surfactant used for intubation?
Subsequently, in selected patients, surfactant administration may be considered an alternative to intubation with prophylactic or early surfactant administration. Surfactant replacement therapy is administered by trained personnel in a clinical setting where equipment for intubation and resuscitation are readily available.
Is surfactant toxic to the body?
Given that surfactant is a substance produced in the body and administered only when deficient, there have not been any serious reports of toxicities related to surfact ant administration. The prerequisites for administration, namely endotracheal intubation and CPAP usage, carry some inherent risks, as mentioned above.
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 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.
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.
Why does the surface of a surfactant increase during inspiration?
The surface increases during inspiration, which consequently opens space for new surfactant molecules to be recruited to the interface.
What are the two proteins that are primarily attributed to surfactant immune function?
Surfactant immune function is primarily attributed to two proteins: SP-A and SP-D. These proteins can bind to sugars on the surface of pathogens and thereby opsonize them for uptake by phagocytes. It also regulates inflammatory responses and interacts with the adaptive immune response.
Why is surfactant important for the lungs?
Lung surfactant makes it easier for oxygen to penetrate the lung surface lining and move into the blood. Without the lung surfactant it would be extremely hard to breathe, and transfer of oxygen through the surface that lines the lungs would be very difficult.
What are Lung surfactants?
Lung surfactants are made from animal lung extract and contain phospholipids. Natural surfactant is produced by the alveolar cells in the lungs and line mainly the alveoli and small bronchioles, and prevents the alveoli from collapsing. Lung surfactant makes it easier for oxygen to penetrate the lung surface lining and move into the blood. Without the lung surfactant it would be extremely hard to breathe, and transfer of oxygen through the surface that lines the lungs would be very difficult.
Why do we need pulmonary surfactant?
Therefore, pulmonary surfactant allows the lungs to expand so air can enter and gas exchange can occur . Respiratory distress syndrome, or (RDS), occurs when a person cannot breathe due to lack of sufficient surfactant. RDS is a breathing disorder that affects newborns. While it rarely occurs in full-term infants, it is most common in premature infants. For example, nearly all infants born before 28 weeks gestation will not have enough surfactant to be able to breathe without assistance.
What is the purpose of water in the lungs?
Our lungs are lined with a thin layer of water. The water creates surface tension, which makes it difficult for the lungs to expand and allow for gas exchange. Pulmonary surfactant is made by our lungs and decreases the surface tension so we can breathe. Updated: 10/31/2019. Create an account.
Why is surface tension important?
As it turns out, the thin layer of water lining the respiratory system presents a challenge. While the water is necessary for gas exchange, it creates surface tension that makes ventilation difficult. Have you ever performed a belly flop off a diving board into a swimming pool? If you have, then you have experienced the effect of surface tension, an attractive force created by chemical bonds between water molecules at a water's surface. This property is the reason why water can resist external force. Surface tension allows insects to walk on water and holds water together in drops dripping from a leaking faucet. For that matter, have you ever played the backyard game Red Rover? Think of the people holding hands as being like water molecules creating surface tension. In order to break through the line, the runner has to force the people's hands apart.
What does surface tension do to the respiratory system?
Okay, so what does surface tension have to do with the respiratory system and gas exchange? In short, surface tension created by water lining the respiratory system prevents the lungs from expanding. Not only do the water molecules hold onto each other, they hold onto the cells lining the respiratory system as well. Here, the surface tension creates an inward directed force, and that prevents the lungs from expanding. This is a problem as breathing is not possible unless the lungs can expand. If we can't breathe in fresh air, gas exchange cannot occur.
Why are lungs wet?
Lungs are kept wet inside the body so that the gas exchange needed for respiration can occur. Have you ever wondered why lungs are on the inside of land-dwelling animals, while gills are on the outside of fish? In order for oxygen and carbon dioxide to get into and out of the blood, these gases have to cross a wet surface.
Can you breathe in fresh air?
This is a problem as breathing is not possible unless the lungs can expand. If we can't breathe in fresh air, gas exchange cannot occur. Pulmonary Surfactant. Fortunately, specialized cells within the lungs produce pulmonary surfactant, which decreases the surface tension by breaking the bond between water molecules.
