Physiology Ch. 16

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Physiology Ch. 16
2011-09-29 17:20:32

The Respiratory physiology
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  1. Respiration functions:
    • Ventilation
    • Gas Exchange
    • 02 Utilization
  2. Ventilation
    • The act of breathing
    • The mechanical process that moves air into and out of the lungs
  3. Gas Exchange
    • occurs at two locations
    • between air and capillaries in the lungs
    • between systemic capillaries and tissues of the body
  4. O2 utilization
    known as cellular respiration
  5. Alveoli (air sacs)
    • Polyhedral in shape and clustered like units of honeycomb
    • 300 million air sacs
    • Each alveolus is 1 cell layer thick
  6. 2 types of cells: Alveoli (air sacs)
    • Alveolar type I: Structural cells
    • Alveolar type II: Secrete surfactant
  7. Gas change; 2 Zones
    • Respiratory Zone
    • Conducting Zone
  8. Respiratory Zone
    • Region of gas exchange between air and blood (alveoli & capillaries)
    • Respiratory bronchioles and alveolar sacs
    • Must contain alveoli
  9. Conducting Zone
    • Includes all of the anatomical structures through which air passes before reaching the respiratory zone
    • Trachea---> Terminal Bronchioles (No gas exchange)
  10. Intra/pleural space:
    • Space between visceral and parietal pleurae
    • Visceral pleura: covers the organ
    • Parietal pleura: lines the cavity wall
    • Contains only a film of fluid secreted by the membranes
  11. Intrapulmonary pressure:
    Intra alveolar pressure (pressure in the alveoli)
  12. Intrapleural pressure
    • Pressure in the intrapleural space
    • This pressure is negative, due to lack of air in the intrapleural space
  13. Transpulmonary Pressure
    Pressure difference across the wall of the lung (inside vs outside)
  14. Transpulmonary Pressure
    During inspiration:
    Atmospheric pressire is > intrapulmonary pressure (-3 mmHg) high to low
  15. Transpulmonary Pressure
    During expiration:
    Intrapulmonary pressure(+3 mm Hg) is > atmospheric pressure
  16. Boyles Law
    Changes in intrapulmonary pressure ocur as a result of changes in lung volume because of gas is inversely proportinal to its volume
  17. Boyles Law
    Increase in lung volume ______ intrapulmonary pressure
    • decreases
    • Air goes in
  18. Boyles Law
    Decrease in lung volume _____intrapulmonary pressure above atmosphere.
    • raises
    • air goes out
  19. Ventilation occurs as a result of pressure_____ induced by changes in____ _____.
    differences; lung volume
  20. 3 physical properties that affect lung function:
    • Compliance
    • Elasticity
    • Surface tension
  21. Compliance
    Stretchability: Ease with which the lungs can expand
  22. Elasticity
    • Tendency to return to initial size after distension
    • High content of elastin proteins
    • Has recoil ability
    • Elastic tension increases during inspiration and is reduced by recoil during expiration
  23. Surface Tension
    • Force exerted by fluid in alveoli to resist distension
    • Lungs secrete and absorb fluid, leaving a very thin film of fluid
    • This film of fluid causes surface tension
  24. Law of Laplace:
    Pressure in alveoli is:
    • Directly proportional to surface tension
    • ^ increase ST ^ increase pressure in alveoli
    • Inversely proportional to radius of alveoli
    • decrease radius ^increase pressure
  25. Surfactant
    • Plays a vitale role in newborns
    • A phospholipid produced by alveolar type II cells
    • Lowers surface tension
    • As alveoli radius decreases, surfactant's abilty to lower surface tension
  26. Quiet Inspiration
    Active process
    Contraction of diaphragm, increases thoracic volume vertically
  27. Quiet Inspiration
    Parasternal and external intercostals contract
    raising ribs; increasing thoracic volume laterally
  28. Expiration
    • Quiet expiration is a passive process
    • Decrease in lung volume raises the pressure within alveoli above atmosphere and pushes air out