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The respiratory system


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The structure and function of th respiratory system, and the mechanics of breathing at rest and during exercise.

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The respiratory system

  1. 1. The Respiratory System Structure, Function, Mechanics of Breathing (External Respiration)
  2. 2. Questions you need to answer <ul><li>What is the function of the respiratory system? </li></ul><ul><li>Describe the passage of air from the body into the blood. </li></ul><ul><li>Explain the mechanics of breathing and how they change during exercise. </li></ul>
  3. 5. Air Pathways and Partial Pressures <ul><li>Air passes into; </li></ul><ul><ul><ul><li>Lungs </li></ul></ul></ul><ul><ul><ul><li>Bronchus </li></ul></ul></ul><ul><ul><ul><li>Bronchi </li></ul></ul></ul><ul><ul><ul><li>Bronchioles </li></ul></ul></ul><ul><ul><ul><li>Alveoli </li></ul></ul></ul><ul><ul><ul><li>at alveoli air passes through the one cell thick sacs into pulmonary capillaries </li></ul></ul></ul><ul><ul><ul><li>O 2 passes in and CO 2 out. </li></ul></ul></ul>
  4. 6. Mechanics of Breathing <ul><li>Inspiration </li></ul><ul><ul><ul><li>external ribs contract - pull ribs up, sternum out </li></ul></ul></ul><ul><ul><ul><li>diaphragm contracts and flattens </li></ul></ul></ul><ul><ul><ul><li>decrease air pressure in thoracic cavity, lung volume increases - air rushes to fill the lungs </li></ul></ul></ul><ul><li>Expiration </li></ul><ul><ul><ul><li>passive relaxation of the respiratory muscles and elastic recoil of lungs - air forced out of the lungs </li></ul></ul></ul><ul><ul><ul><li>forced expiration internal intercostal muscles and abdominals contract to pull ribs down and pull diaphragm up </li></ul></ul></ul>
  5. 7. Gaseous Exchange Internal Respiration, Breathing Control, Respiratory Volumes and measures
  6. 8. Questions you need to answer <ul><li>Describe gaseous exchange at the alveoli and movement of oxygen due to partial pressure. </li></ul><ul><li>Explain the effect of temperature, acidity, and carbon dioxide on oxygen dissociation. </li></ul><ul><li>Explain how breathing rate and depth is controlled by the body. </li></ul><ul><li>Know the definitions of breathing volumes and typical values at rest and exercise. </li></ul>
  7. 10. Partial Pressure of gases (mmHg) <ul><li>Oxygen (0 2 ) Carbon Dioxide (CO 2 ) </li></ul><ul><li>160 Atmosphere 0.3 </li></ul><ul><li>105 Alveoli 40 </li></ul><ul><li>40 Tissues 45 </li></ul>
  8. 11. <ul><li>O 2 attracted into capillaries by partial pressure of gases and haemoglobin. </li></ul><ul><ul><ul><li>97% O 2 carried in this way. </li></ul></ul></ul><ul><li>Oxygen saturation of haemoglobin is affected by several factors as well as its own partial pressure </li></ul><ul><ul><ul><li>body temperature </li></ul></ul></ul><ul><ul><ul><li>partial pressure of CO 2 </li></ul></ul></ul><ul><ul><ul><li>acidity ‘Bohr Effect’ </li></ul></ul></ul><ul><li>Only 23% CO 2 carried by haemoglobin </li></ul><ul><ul><ul><li>70% combines with water to form carbolic acid which is buffered by hydrogen ions to form Bicarbonate . </li></ul></ul></ul>
  9. 12. Breathing Control <ul><li>Controlled by the respiratory centre in the medulla oblongata. </li></ul><ul><ul><ul><li>The inspiratory centre controls rhythmic cycle of in/expiration during rest. </li></ul></ul></ul><ul><ul><ul><li>The expiratory centre is inactive at rest but affects breathing during exercise </li></ul></ul></ul><ul><li>2 methods of control </li></ul><ul><ul><ul><li>Neural </li></ul></ul></ul><ul><ul><ul><li>Chemical </li></ul></ul></ul>
  10. 13. <ul><li>Volumes </li></ul><ul><li>Tidal Volume </li></ul><ul><ul><ul><li>air breathed in/out each breath </li></ul></ul></ul><ul><li>Inspiratory Volume </li></ul><ul><ul><ul><li>max volume inspired after tidal volume </li></ul></ul></ul><ul><li>Expiratory Volume </li></ul><ul><ul><ul><li>max volume expired after tidal volume </li></ul></ul></ul><ul><li>Residual Volume </li></ul><ul><ul><ul><li>volume left in lungs after max expiration (stops lungs collapsing) </li></ul></ul></ul><ul><li>Measures </li></ul><ul><li>Vital Capacity </li></ul><ul><ul><ul><li>max air expired after inspiring as much as possible </li></ul></ul></ul><ul><li>Total Lung Capacity </li></ul><ul><ul><ul><li>vital capacity + residual volume </li></ul></ul></ul><ul><li>Minute Ventilation </li></ul><ul><ul><ul><li>Tidal Volume x frequency of breathing per minute </li></ul></ul></ul>