elastic recoil

Examples of elastic recoil in the following topics:

• Factors Affecting Pulmonary Ventilation: Compliance of the Lungs

  • Compliance is inversely related to the elastic recoil of the lungs, so thickening of lung tissue will decrease lung compliance.
  • A low lung compliance means that the lungs are "stiff" and have a higher than normal level of elastic recoil.
  • A high lung compliance means that the lungs are too pliable and have a lower than normal level of elastic recoil.
  • Exhalation of air also becomes much more difficult because the loss of elastic recoil reduces the passive ability of the lungs to deflate during exhalation.
  • High lung compliance is commonly seen in those with obstructive diseases, such of emphysema, in which destruction of the elastic tissue of the lungs from cigarette smoke exposure causes a loss of elastic recoil of the lung.

• Functional Anatomy of the Respiratory System

  • The lungs have high degree of elastic recoil, so they rebound from the stretch of inhalation and air flows out until the pressures in the lungs and the atmosphere reach equilibrium.
  • The reason for the elastic recoil of the lung is the surface tension from water molecules on the epithelium of the lungs.
  • Forced exhalation is often used as an indicator to measure airway health, as people with obstructive lung diseases (such as emphysema, asthma, and bronchitis) will not be able to actively exhale as much as a healthy person because of obstruction in the conducting zones from inhlation, or from a loss of elastic recoil of the lungs.

• Elastic Arteries

  • An elastic artery or conducting artery is an artery with a large number of collagen and elastin filaments in the tunica media.
  • The pulmonary arteries, the aorta, and its branches together comprise the body's system of elastic arteries.
  • Additionally, the elastic recoil helps conserve the energy from the pumping heart and smooth the flow of blood around the body through the Windkessel effect.
  • In elastic arteies the tunica media is very rich with elastic and connective tissue.
  • The aorta makes up most of the elastic arteries in the body.

• Alveoli

  • The alveoli are highly elastic, so the alveoli can stretch as they are filled with air during inhalation.
  • Type II (Great Alveolar) cells: These are the site of surfactant production in the lungs, making them critical for maintaining the elastic recoil of the lung.
  • The surfactant produced by type II epithelial cells is very important for maintaining the elastic recoil of the lungs.

• The Mechanics of Human Breathing

  • The lungs are elastic; therefore, when air fills the lungs, the elastic recoil within the tissues of the lung exerts pressure back toward the interior of the lungs.
  • Upon exhalation, the lungs recoil to force the air out of the lungs.

• The Work of Breathing

  • Breathing includes several components, including flow-resistive and elastic work; surfactant production; and lung resistance and compliance.
  • There are two types of work conducted during respiration: flow-resistive and elastic work.
  • When the respiratory rate is decreased, the flow-resistive work is decreased and the elastic work is increased.
  • The overall compliance of the lungs is increased, because as the alveolar walls are damaged, lung elastic recoil decreases due to a loss of elastic fibers; more air is trapped in the lungs at the end of exhalation.
  • Explain the roles played by surfactant, flow-resistive and elastic work, and lung resistance and compliance in breathing

• Expiration

  • The primary reason that expiration is passive is due to the elastic recoil of the lungs.
  • The elasticity of the lungs is due to molecules called elastins in the extracellular matrix of lung tissues and is maintained by surfactant, a chemical that prevents the elasticity of the lungs from becoming too great by reducing surface tension from water.
  • Because the lung is elastic, it will automatically return to its smaller size as air leaves the lung.
  • This happens due to elastic properties of the lungs, as well as the internal intercostal muscles that lower the rib cage and decrease thoracic volume.

• Elastic Collisions in One Dimension

  • An elastic collision is a collision between two or more bodies in which kinetic energy is conserved.
  • An elastic collision will not occur if kinetic energy is converted into other forms of energy.
  • It important to understand how elastic collisions work, because atoms often undergo essentially elastic collisions when they collide.
  • On the other hand, molecules do not undergo elastic collisions when they collide .
  • The mathematics of an elastic collision is best demonstrated through an example.

• Types of Connective Tissue

  • Dense connective tissue is divided into 1) dense regular, 2) dense irregular, 3) elastic.
  • The main fibers that form this tissue are elastic in nature.
  • These fibers allow the tissues to recoil after stretching.
  • Cartilage is classified in three types: 1) elastic cartilage, 2) hyaline cartilage, and 3) fibrocartilage, which differ in the relative amounts of these three main components.
  • This is similar to hyaline cartilage but is more elastic in nature.

• The Compton Effect

  • Still, the origin of the effect can be considered as an elastic collision between a photon and an electron.
  • Thomson scattering, the classical theory of an electromagnetic wave scattered by charged particles, cannot explain low intensity shifts in wavelength: classically, light of sufficient intensity for the electric field to accelerate a charged particle to a relativistic speed will cause radiation-pressure recoil and an associated Doppler shift of the scattered light.