Elastic recoil
Encyclopedia
Elastic recoil is the rebound of the lungs
after having been stretched by inhalation
, or rather, the ease with which the lung rebounds. With inhalation, the interpleural pressure (the pressure within the pleural cavity
) of the lungs decreases. Relaxing the diaphragm during expiration allows the lungs to recoil and regain the interpleural pressure experienced previously at rest. Elastic recoil is inversely related to lung compliance
.
This phenomenon occurs because of the elastic fibers in the connective tissue of the lungs and because of the surface tension of the film of fluid that lines the alveoli. As water molecules pull together, they also pull on the alveolar walls causing the alveoli to recoil and become smaller. But two factors prevent the lungs from collapsing: surfactant and the interpleural pressure. Surfactant
is a surface-active lipoprotein complex formed by type II alveolar cells. The proteins and lipids that comprise surfactant have both a hydrophilic region and a hydrophobic region. By adsorbing to the air-water interface of alveoli with the hydrophilic head groups in the water and the hydrophobic tails facing towards the air, the main lipid component of surfactant, dipalmitoylphosphatidylcholine, reduces surface tension. It also means the rate of shrinking is more regular because of the stability of surface area caused by surfactant. Pleural pressure is the pressure in the pleural space. When this pressure is lower than the pressure of alveoli they tend to expand. This prevents the elastic fibers and outside pressure from crushing the lungs. It is a homeostatic
mechanism.
Human lung
The human lungs are the organs of respiration in humans. Humans have two lungs, with the left being divided into two lobes and the right into three lobes. Together, the lungs contain approximately of airways and 300 to 500 million alveoli, having a total surface area of about in...
after having been stretched by inhalation
Inhalation
Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli....
, or rather, the ease with which the lung rebounds. With inhalation, the interpleural pressure (the pressure within the pleural cavity
Pleural cavity
In human anatomy, the pleural cavity is the potential space between the two pleura of the lungs. The pleura is a serous membrane which folds back onto itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity; it normally...
) of the lungs decreases. Relaxing the diaphragm during expiration allows the lungs to recoil and regain the interpleural pressure experienced previously at rest. Elastic recoil is inversely related to lung compliance
Pulmonary compliance
Pulmonary compliance can refer to either dynamic or static lung compliance. Static lung compliance is the change in volume for any given applied pressure...
.
This phenomenon occurs because of the elastic fibers in the connective tissue of the lungs and because of the surface tension of the film of fluid that lines the alveoli. As water molecules pull together, they also pull on the alveolar walls causing the alveoli to recoil and become smaller. But two factors prevent the lungs from collapsing: surfactant and the interpleural pressure. Surfactant
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
is a surface-active lipoprotein complex formed by type II alveolar cells. The proteins and lipids that comprise surfactant have both a hydrophilic region and a hydrophobic region. By adsorbing to the air-water interface of alveoli with the hydrophilic head groups in the water and the hydrophobic tails facing towards the air, the main lipid component of surfactant, dipalmitoylphosphatidylcholine, reduces surface tension. It also means the rate of shrinking is more regular because of the stability of surface area caused by surfactant. Pleural pressure is the pressure in the pleural space. When this pressure is lower than the pressure of alveoli they tend to expand. This prevents the elastic fibers and outside pressure from crushing the lungs. It is a homeostatic
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
mechanism.