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Why gas exchange?

Why gas exchange?. Often gas exchange is called respiration Is not the same as cellular respiration, but is a consequence of the process. O 2. O 2. O 2. O 2. O 2. O 2. O 2. O 2. What is gas exchange?. CO 2. CO 2. CO 2. CO 2. CO 2. CO 2.

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Why gas exchange?

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  1. Why gas exchange? • Often gas exchange is called respiration • Is not the same as cellular respiration, but is a consequence of the process

  2. O2 O2 O2 O2 O2 O2 O2 O2 What is gas exchange? CO2 CO2 CO2 CO2 CO2 CO2 • Is the uptake of O2 and discharge of CO2 as a result of ventilation • Involves both circulatory and respiratory systems CO2 CO2 CO2 CO2 O2 CO2 O2 O2 O2 O2 O2 O2 O2 O2 O2 O2 CO2 CO2 alveolus capillary tissue

  3. Requirements of respiratory surfaces • Respiratory surfaces must be moist • Should have a large surface area • Should be thin

  4. Gills • Thin, highly vascular • Cross-current flow of water allows an oxygen gradient to develop

  5. Tracheal System • Consist of small openings on exoskeleton’s exterior that open to small tracheae leading to air sacs inside

  6. Why a ventilation system? • Concentration gradients of respiratory gases must be maintained in alveoli so that cells get oxygen they need for cellular respiration

  7. Ventilation system structure

  8. Negative Pressure Breathing • Pressure of the chest cavity falls upon inhalation: application of Boyle’s law

  9. Avian Lungs • Air sacs keep air flowing in one direction • Helps decrease bird’s density • Gas exchange happens in air tubes in lungs, not alveoli

  10. Control of Breathing • Chemoreceptors in medulla detect changes in CO2 concentration • Chemoreceptors in aorta, carotid detect changes in O2

  11. Partial pressure of a gas • The air we breathe is a mixture of gases • Partial pressure is the pressure of the individual gases in the mixture • It is the partial pressures of each gas that allows them to diffuse into or out of alveoli: a concentration gradient is established

  12. Oxygen dissociation curves • Respiratory pigments must be able to load and unload O2 • Tissues at rest can unload more O2 than exercising tissues • Think about why!

  13. How CO2 is carried in blood • Hgb picks up the CO2 and H+ ions, which are converted to carbonic acid • This dissociates into bicarbonate and H+ ions in blood • At alveoli, Hgb releases CO2 and H+ • Chloride shift: occurs due to Cl- ions being transported across with HCO3- so venous blood has higher [Cl-].

  14. Bicarbonate buffer system • Keeps blood pH at a certain level so that acidosis or alkalosis are avoided • Proper pH is crucial to O2 transport by Hgb • Bohr shift: Hgb loses affinity for O2 at lower pH levels, will unload O2 to restore pH to normal

  15. Fetal vs. Maternal Hgb • Fetal hemoglobin has a higher saturation rate at lower partial pressures than maternal Hgb • Think about why!

  16. Elite Animal Athletes…(for Anthony) • Running mammals must sustain speed and endurance • Ex: Pronghorns consume O2 at 3x the rate predicted for an animal its size. How? • Larger surface area in lungs, higher muscle mass, more mitochondria • Diving mammals • Ex: Seals remain 200-500m underwater for 20-60 min. How? • Stockpile O2 in their blood, increased blood volume, myoglobin in muscles stores O2.

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