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Lecture 5 gas exchange


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Lecture 5 gas exchange

  1. 1. Lecture 5. Gas Exchange• cellular respiration, oxidative processes within cells• external respiration, exchange of O2 and CO2 between the organism and its environment
  2. 2. Gas Exchange Surfaces• for diffusion to be effective, gas-exchange regions must be: – moist – thin – relatively large• effectiveness of diffusion is enhanced by vascularization
  3. 3. Respiratory Organs• cutaneous respiration (direct diffusion)
  4. 4. Respiratory Organs• Tracheal systems (branching system of tubes)
  5. 5. Respiratory Organs• Gills or branchia (external or internal) papulae (dermal branchiae or skin gills)
  6. 6. Respiratory Organs• Gills or branchia (external or internal) gills in axolotl (Ambystoma mexicanum) branchial tufts (gills) in marine worm
  7. 7. Respiratory Organs• Gills or branchia (external or internal)parapodia in ragworm (Nereis spp.)
  8. 8. Respiratory Organs• Gills or branchia (external or internal)
  9. 9. How a fish ventilates its gills
  10. 10. countercurrent flow/exchangeCopyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
  11. 11. Respiratory Organs• Lungs (invaginations)
  12. 12. • Lungs of frogs A frog ventilates its lungs by positive pressure breathing.
  13. 13. • Lungs of mammals
  14. 14. • Lungs of mammals Mammals ventilate their lungs by negative pressure breathing.
  15. 15. • Lungs of birds
  16. 16. • Lungs of birds
  17. 17. • the volume of air an animal inhales and exhales with each breath is called tidal volume – it averages about 500 mL in resting humans• the maximum tidal volume during forced breathing is the vital capacity – about 3.4 L and 4.8 L for college-age females and males, respectively
  18. 18. • most animals transport most of the O2 bound to special proteins called respiratory pigments – hemocyanin – hemoglobin
  19. 19. • when the control center registers a slight drop in pH, it increases the depth and rate of breathing, and the excess CO2 is eliminated in exhaled air
  20. 20. • O2 diffuses into pulmonary capillaries• most O2 combines with hemoglobin in red blood cells to form oxyhemoglobin• CO2 diffuses out of pulmonary capillaries• most CO2 is transported in the form of bicarbonate ion• some CO2 combines with hemoglobin to form carbaminohemoglobin
  21. 21. Fig. 31.27
  22. 22. • cooperative oxygen binding and release is evident in the dissociation curve for hemoglobin
  23. 23. • a drop in pH lowers the affinity of hemoglobin for O2, an effect called the Bohr shift