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Animal Respiration

Animal Respiration. Lecture #4. Respriation. Involves the diffusion of gases Oxidative respiration consumes O 2 and produces CO 2 Respiration is the process of obtaining O 2 and getting rid of CO 2 This is done by passive diffusion. CO 2 CO 2 O 2 O 2. Composition of Air.

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Animal Respiration

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  1. Animal Respiration Lecture #4

  2. Respriation • Involves the diffusion of gases • Oxidative respiration consumes O2 and produces CO2 • Respiration is the process of obtaining O2 and getting rid of CO2 • This is done by passive diffusion. • CO2CO2 • O2O2

  3. Composition of Air • All O2 in the air is a result of photosynthesis. • O2 producing organisms first appeared in the ocean. • O2 dissolved in water then diffused into atmosphere. • Then, terrestrial plants added O2 to the atmosphere

  4. Composition of Air (II) • Nitrogen (N2)………………78.09% • Oxygen (O2 )………………20.95% • Argon and inert gases………0.93% • Carbon Dioxide (CO2)……..0.03% • Because of convection currents, composition of air is the same throughout the world.

  5. BUT • Composition is the same in a horizontal plane. • Amount of air in a vertical plane is not the same. • As altitude increases, the amount of air decreases.

  6. Air is comprised of molecules. • Therefore, air has • A weight • A pressure • Consider a column or tube of air going from sea level up until there was no more air. • The weight would cause a pressure = a column of 760mm of Hg (mercury) = 1 atmosphere • Weather Channel watchers = 29.92 in

  7. 1 Atmosphere = 760mm pressure • Each gas in atmosphere contributes a partial pressure to the total atmospheric pressure. • PN = 78.08% X 760mm = 600.6mm Hg • PO = 20.95% X 760mm = 159.2mm Hg • At sea level, air pressure is 760mm Hg. • But as altitude increases, column gets shorter = air pressure  • Partial pressure of O2 (PO) also 

  8. Physics of Respiration • Diffusion of O2 across a cell membrane is • Passive • Depends upon the concentration gradient • Limited by distance • (don’t write this down) . We can put this all into a physical equation.

  9. Fick’s Law of Diffusion • Approximates rate of diffusion (R) between 2 regions R = D x A x p/d • D = diffusion constant • A = area over which diffusion takes place • p = concentration gradient [in] vs. [out] • d = distance across which diffusion has to take place

  10. Evolution of Respiration • Single Cells • Limited by size….why? • d = distance of diffusion • Surface [O2 ] would be depleted.

  11. Creating a Water Current • Primitive phyla got rid of O2 depleted water…..how? 1. flagella

  12. 2. Movement • In these organisms, ext. [O2 ] never 

  13. Increasing Diffusion Surface Area • Advanced invertebrates and vertebrates develop organs that do this. • They  R by  A • They also  d

  14. And the champion is?

  15. Fish – Most Efficient • Why? •  A (gills) •  p (countercurrent flowof water over gills)

  16. Structure of Gills • Water comes in mouth and passes over gills =  p

  17. Gill Structure  A • Gills segmented into gill filaments = A

  18. Countercurrent Flow • Blood flow in gills opposite that to water flow. • Least [O2 ] blood meets least [O2 ] water at back of gill • Most [O2 ] blood meets most [O2 ] water at front of gill • Result – most efficient blood oxygenation known in nature

  19. Countercurrent vsConcurrent Exchange

  20. Water to Land • More O2 in air than in water • Water = 0.5 – 1% • Land = ~ 21% • Many members of aquatic group (molluscs, crustaceans and fish) came on land. • Two problems to overcome • Gills collapsed….no support • Water evaporation of gills

  21. Two types of respiration on land A. Insects developed trachea.

  22. Insects • Trachea are air-filled passageways connected to all parts of the body. • They close when CO2 levels  •  water evaporation

  23. Vertebrates • B. Lungs

  24. Amphibians • Earliest terrestrial vertebrates • First to abandon one way respiration • Not a very efficient lung • Could breath with its mouth closed • Could breath through its skin (cutaneous) • Had to have moist skin

  25. Amphibians

  26. Reptiles • More active than amphibians • Require more O2 • Total terrestrial life….no O2 exchange through skin • Dry skin….no dessication (water loss) • Skin is water tight • Lung has  A vs. to amphibian

  27. Mammals • O2 consumption much greater than most animals •  A • 300 x 106 small sacs called alveoli • Structure of human lung

  28. Alveoli

  29. Alveoli

  30. Human Lung

  31. Lung Pathologiesand Fick’s Law • Emphysema – shortness of breath and inability to do physical exercise (A) • Cystic fibrosis – secretion of thick mucus which D • Respiratory distress syndrome – leading cause of death in premature infants (d)

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