Gas Exchange

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  1. Organisms must exchange ____ and ____ aka ______ gases. This is done via ______ along their concentration gradients. Gas exchange systems are made up of ______ and the ______ that ______ and ______ them.
    • CO2 & O2
    • respiratory gases
    • diffusion
    • surfaces 
    • mechanisms
    • ventilate & perfuse
  2. Partial pressure 
    Barometric pressure
    • partial pressure: the concentration of a gas in a mixture
    • barometric pressure: is the pressure exerted by the weight of air in the atmosphere of Earth (or that of another planet)
  3. Fick's law of diffusion applies to all _____ _____ systems. 

    What is Q?
    What is D?
    What is A?
    gas exchange systems

    • Q: rate of diffusion
    • D: the diffusion coefficient (a charac. of the diffusing substance, the medium (like water vs air) and temp.) 
    • A: the area where diffusion occurs
  4. Q=DA(P1-P2/L) 
    What are P1 & P2?
    What is L?
    What does (P1-P2)/L signify?
    • P1 & P2: partial pressures of the gas at two locations
    • L: the path length between the locations
    • (P1-P2)/L: a partial pressure gradient
  5. The _____ rate of diffusion of oxygen in water limits the ____ & _____ of species without internal systems for ____ ____. These species have evolved to have ______ surface areas, or _____ ______, or ________ _______ systems
    • slow 
    • size and shape 
    • gas exchange
    • larger 
    • central cavities
    • specialized respiratory systems
  6. _______ is easier to obtain from the air than from water

    State 3 reasons why this is so.

    • O2 content of air is higher than that of water
    • O2 diffuses much faster through air
    • Air and water must be moved by the animal over its gas exchange surfaces—requires more energy to move water than air
  7. Respiratory gas exchange is a two-way process explain.
    CO2 diffuses out of the body as O2 diffuses in
  8. The concen. gradient of CO2 from air breathers to the environment is always ______. CO2 is _____ soluble in water and is easy for aquatic animals to _____.
    • large
    • very 
    • exchange
  9. Some respiratory systems have adaptations to maximize the exchange of O2 and CO2. Name 4 such adaptations
    • Increased surface area (A)
    • Maximized partial pressure gradients (P1-P2)
    • Minimized diffusion path length (L)
    • Minimize the diffusion that takes place in an aqueous medium (D)
  10. Name 4 ways Surface area is increased
    • External gills—also minimize the diffusion path length (L) of O2 and CO2 in water
    • Internal gills—protected from predators and damage
    • Lungs—internal cavities for respiratory gas exchange with air
    • Tracheae—air-filled tubes in insects
  11. Air enters the human lungs through the ____ ____ or the ______ ______, both of which join in the _______.
    • oral cavity 
    • nasal passage
    • pharynx
  12. Below the pharynx, the ______ (at the beginning is the voice box or _____)leads to the _____
    • trachea 
    • larynx 
    • lungs
  13. The trachea branches into two _____, then into _______, and then into _______ (the site of gas exchange)
    • bronchi
    • bronchioles 
    • alveoli
  14. Capillaries surround and lie between the ______, here the _____ path between _____ & ____ is less than two micrometers.
    • alveoli
    • diffusion 
    • blood & air
  15. ________ from smoking destroys alveoli
  16. Respiratory gases are transported in the _____. Blood plasma carries _____ O2, however the blood contains molecules that _____ _____ to O2. O2 is picked up where its partial pressure is _____ and released where its partial pressure is ______.
    • Blood
    • little 
    • binds reversibly 
    • high
    • lower
  17. Hemoglobin is protein with four ______ ______ and is an O2 ______
    • polypeptide subunits 
    • transporter
  18. In hemoglobin, each polypeptide surrounds a _____ _____ that can bind a molecule of _____. One hemoglobin can bind up to ____ _____
    • heme group
    • O2 
    • four oxygens
  19. The relationship between PO2 and O2 is that binds is ______. Low PO2 means one ______ binds O2.
    • S-shaped
    • subunit
  20. Positive cooperativity
    one subunit binds and changes shape, making it easier for the next one to bind—the affinity for O2 is increased.
  21. When _____ subunits are bound, a larger increase in PO2 is needed.
  22. Myoglobin is a single ______ _____ in
    muscles and can bind ___ molecule of O2. It has a ______ affinity for O2, binds it at low PO2 values when ______ molecules would release their O2
    • polypeptide molecule
    • one
    • higher
    • hemoglobin
  23. Myoglobin provides a reserve for high _______ demand for O2
  24. The affinity of hemoglobin for O2 varies. Three
    factors are:
    • Hemoglobin composition
    • pH—in the Bohr effect, blood circulating through active tissues has a lower pH and H+ ions bind to the hemoglobin molecule in place of O2
    • 2,3-bisphosphoglyceric acid (BPG)—also lowers the affinity for O2 (byproduct of glycolysis)
  25. CO2 is transported ____ from the tissues after diffusing into the blood. In the blood plasma, CO2 is slowly converted into ______ ___. In endothelial cells and red blood cells ______ _______ speeds up the conversion.
    • away 
    • bicarbonate ions (HCO3-)
    • carbonic anyhydrase
  26. The conversion of CO2 to bicarbonate (2)
    • keeps PCO2 low
    • facilitates diffusion away from the tissues.
  27. Some CO2 binds to _______ molecules. In the lungs the conversion reaction is _______, CO2 diffuses from the _____ into the _____ and is ______
    • hemoglobin
    • reversed
    • blood 
    • alveoli
    • exhaled
  28. Breathing is controlled in the _____ specifically the _____. In ______ and _______, the breathing rate is more sensitive to changes in PCO2 than to PO2. The PCO2 of blood is the _____ ______ ______ for breathing.
    • brainstem
    • medulla
    • humans and mammals 
    • primary metabolic feedback

Card Set Information

Gas Exchange
2016-11-17 08:03:01
Week 7
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