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.

• Inspiration

  • The force of the intrapleural pressure is even enough to hold the lungs open during inpiration despite the natural elastic recoil of the lung.

• 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.

• Arterial Blood Pressure

  • The tunica media of arteries is thickened compared to veins featuring more smooth muscle fibers and elastic tissue.
  • Together, these allow for the generation of elastic recoil and contraction of the blood vessel allowing for the maintenance of a higher pressure.

• Lungs

  • The elastic recoil of the lungs automatically pulls the lungs inward during exhalation.

• 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.

• Muscular Arteries

  • Distributing arteries are medium-sized arteries that draw blood from an elastic artery and branch into "resistance vessels".
  • Muscular, or distributing, arteries are medium-sized arteries that draw blood from an elastic artery and branch into "resistance vessels" including small arteries and arterioles.
  • In contrast to the mechanism elastic arteries use to store and dissipate energy generated by the heart's contraction, muscular arteries contain layers of smooth muscle providing allowing for involuntary control of vessel calibre and thus control of blood flow.
  • Muscular arteries can be identified by the well defined elastic lamina which lies between the tunicae intima and media.