Chapter 11

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  1. On hat does the movement of gases between the lungs and the body tissue mainly depend?
    A. active transport
    b. gaseous diffusion
    c. membrane dialysis
    d. membrane transport

    Gas movement between the lungs and tissues occurs by simple diffusion
  2. The lowest PO2 would normally be found in what location?
    A. arterial blood
    b. atmospheric air
    c. cells
    d. venous blood

    The intracellular PO2 (approximately 5 mm Hg) provides the final gradient for oxygen diffusion in to the cell.
  3. The highest PCO2 levels are found in what location?
    A. arterial blood
    b. atmospheric air
    c. cells
    d. venous blood

    The partial pressure of carbon dioxide (PCO2) is highest in the cells ( approximately 60 mm HG)
  4. Which of the following are true regarding PACO2?
    1. Directly proportional to whole-body carbon dioxide production
    2. Inversely proportional to alveolar ventilation (VA)
    3. Normally maintained at about 35-45 mm HG
    1, 2, 3

    PACO2 varies directly with the body's production of carbon dioxide (CO2) inversely with alveolar ventilation(VA). Under normal conditions it is maintained at about 35-45 mm HG
  5. What is the appropriate level of carbon dioxide production (CO2) for an adult?
    A. 200 ml/min
    b. 250 ml/min
    c. 4200 ml/min
    d. 6000 ml/min

    In a healthy individual the normal CO2 of is about 200ml/min
  6. Under what conditions will alveolar PACO2 rise above normal?
    A. if both metabolic rate and ventilation increase (e.g. through exercise)
    b. if carbon dioxide production decreases relative to VA
    c. if V A decreases relative to carbon dioxide production
    d. when a pt is febrile

    The PACO2 will increase above this level if carbon dioxide production increases while VA remains constant or when VA decreases while CO2 remains constant
  7. A 70kg male has CO2 of 200 ml/min and a VA of 9 L/min. From this information, what can you infer?
    A. the pt's CO2 production is abnormally low
    b. the pt's VA is normally low
    c. the pt will have a lower than normal PACO2
    d. the pt will have a higher than normal PACO2

    When the CO2 is normal while the VA is elevated, the PACO2 must be lower then normal. Likewise, the PACO2 will fall if the carbon dioxide production or the alveolar ventilation increases
  8. What is the primary determinant of the PAO2?
    A. body's CO2
    b. metabolic rate of the body tissues?
    c. PaCO2
    d. PO2 in the inspired gas

    Many factors determine the alveolar partial pressure of oxygen (PAO2). Most important is the inspired partial pressure of oxygen or PIO2.
  9. The PAO2 depends on which of the followings factors?
    A. ambient pressure
    b. fractional concentration of inspired oxygen
    c. level of VA
    d. types of fuels burned

    • PAO2 = FIO2 x (PB- 47) - PACO2 x 1.25
    • Where FIO2 is the fraction of inspired oxygen, PB is barometric pressure, 47 is watter vapor tension (in mm HG) at 37 C , PAO2 is alveolar  PCO2, and 0.8 is normal respiratory exchange ratio (R). as VA is the VA is the primary determinant of PACO2 any changes in VA will effect the PAO2. Like wise the fuel source will determine the RQ which is normally 0.8
  10. Which of the following best represents the partial pressure of all gases in the normally ventilated and perfused ALVEOLUS when breathing room air at sea level?
    A. PO2= 40 mm Hg; PCO2= 100 mm Hg; PN2= 573 mm Hg PH2O = 47 mm Hg

    b. PO2= 100 mm Hg; PCO2= 40 mm Hg; PN2= 573 mm Hg PH2O= 47 mm Hg

    c. PO2= 100mm Hg; PCO2= 40mm Hg; PN2= 573 mm Hg PH2O=  47 mm Hg

    d. PO2= 149 mm Hg; PCO2= 40 mm Hg; PN2= 573 mm Hg PH2O= 47 mm Hg
  11. In a person breathing room air (and with all else being normal), if the alveolar PCO2 rises from 40-70 mm Hg, what would you expect?
    A. PAO2 to fall by about 30 mm Hg
    b. PAO2 to fall by about 40 mm Hg
    c. PAO2 to rise by about 30 mm Hg
    d. PAO2 to rise about 40 mm Hg

    Based on alveolar air equation, if the FIO2 remains constant, then the PAO2 must vary inversely with the PACO2
  12. Assuming the FIO2 and the carbon dioxide production, which of the following statements are correct?
    A. an increased in PACO2 will result in and increased PAO2
    b. increased FIO2 blows off carbon dioxide
    c. increased in VA decrease the PACO2 and increases the PAO2
    d. the PAO2 varies proportionally with the PACO2

    With constant carbon dioxide production, a decrease in VA simultaneously raises the PACO2 and lowers the PAO2
  13. What is the PaO2 one could expect to observe in an individual breathing room air at sea level?
    A. 90-100 mm Hg
    b. 110-120 mm Hg
    c. 640-670 mm Hg
    d. 710 -760 mm Hg

    Neural mechanism and the increased work of breathing prevent decreases in PACO2 much below 15-20 mm Hg. Thus whenever a pt is breathing room air at sea level, the respiratory therapist should not expect to see a PaO2 any higher than 120 mm Hg during hyperventilation.
  14. Which of the following conditions must exist for gas to move between the alveolus and pulmonary capillary?

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Chapter 11
2015-06-15 19:13:27

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