Gas Transport by the Blood PPT Respiratory Midterm

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Gas Transport by the Blood PPT Respiratory Midterm
2013-03-14 13:05:54
Boston College CRNA

Gas Transport Lecture/Reading Flashcards
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  1. Oxygen is carried in the blood in what two forms?
    • 1. Dissolved in plasma
    • 2. Combined with Hemoglobin
  2. Which hemoglobin is considered normal adult hemoglobin?
    Hemoglobin A
  3. Which hemoglobin makes up part of the hemoglobin of a newborn and is gradually replaced over the first year or two of life?
    Hemoglobin F (fetal)
  4. Which hemoglobin has reduced oxygen affinity and a causes a right shift of the oxygen dissociation curve?
    Hemoglobin S (sickle)

    -The deoxygenated for is poorly soluble and crystallizes within the red cell. The cell shape changes from biconcave to crescent or sickle shape with increased fragility and a tendency to thrombus formation.
  5. What reversible reaction represents the relationship between oxygen, hemoglobin, and oxyhemoglobin?
  6. When is the oxygen capacity reached?
    When the maximum amount of oxygen is combined with hemoglobin (i.e. all sites are occupied)
  7. Define: oxygen saturation
    The percentage of the available hemoglobin binding sites that have oxygen attached
  8. In general ______ mL oxygen combines with each gram of hemoglobin.
  9. What is the formula for finding oxygen saturation?
    • Oxygen combined with Hgb X 100
    •        Oxygen capacity
  10. What is the formula for oxygen saturation, and why should caution be used when consulting an oxygen saturation?
    • How many sites saturated
    • How many sites total

    -Careful because it doesn't take into account the number of hemoglobin. The patient could be anemic but still satting 100% if all sites are saturated
  11. The change in Hgb from fully oxygenated to deoxygenated is accompanied by a conformational change. 

    What form is oxygenated, what form is deoxygenated?
    • Oxygenated form: R (relaxed state)
    • Deoxygenated form: T (tense state)
  12. Does cyanosis depend on the amount of (1) bound hemoglobin or (2) reduced hemoglobin?
    (2) REDUCED hemoglobin!

    This is why cyanosis is often marked in patients with polycythemia (because there are more reduced hemoglobins!)
  13. Patients with smoke inhalation may have great sats but may still not have great oxygen carrying capacities... why?
    Carbon monoxide has 240x the affinity for hgb than oxygen, carbon monoxide will combine with hgb and therefore reduce the oxygen carrying capacity of the blood
  14. What are some causes of a Right shift in the oxygen dissociation curve?
    Acidosis (increased H+ ion),  Hyperthermia,  Increased 2,3 DPG, Increased PCO2
  15. What are some causes of a Left shift in the oxygen dissociation curve?
    Alkalosis, hypothermia, decreased 2,3 DPG, small addition of CO to blood, massive blood transfusion of refrigerated blood products
  16. What happens on the tissue level during a right shift in the oxygen dissociation curve?
    Oxygen is released more readily by the hemoglobin to the tissues
  17. What happens on the tissue level during a left shift in the oxygen dissociation curve?
    Oxygen is less likely to be given up to the tissues, greater oxygen affinity
  18. What is 2,3 DPG?

    End product of red blood cell metabolism, increased in chronic hypoxia, high altitudes, and patients with chronic lung disease (because RBC are being broken down)
  19. How do you calculate the delivery oxygen? 

    (Formula to figure out: How much 02 is blood actually carrying?)
    D02= Qt (CaO2 x 10)

    • D02: delivery O2
    • Qt: flow; Cardiac Output in L/min
    • 10: in dL need in L
  20. What does the Bohr effect describe?
    The effect of CO2 on the oxygen dissociation curve
  21. Bicarbonate is formed in the blood by what sequence?

    When CO2 increases, it pushes the entire equation to the Right, thats why when CO2 increases so does HCO3-

    -This reaction is slow in the plasma, but fast in the blood stream (because of the presence of carbonic anhydrase)
  22. To maintain electrical neutrality when HCO3- moves out of the cell, what moves in?
    Cl- moves into the cell from the plasma

    This is known as the Chloride shift, the movement of chloride is in accordance with the Gibbs-Donnan equilibrium, also known as Hamburger Effect
  23. Carbon dioxide is carried in the blood in three forms. They are:
    • 1. Dissolved (obeys Henrys Law)
    • 2. Bicarbonate
    • 3. Carbamino compounds

    -Largest form of CO2 in blood is carried by bicarbonate, formed by ionization of H2CO3
  24. What is the Haldane effect?
    • -Reduced hemoglobin can carry more acid (H ion or CO2)
    • -looks at the CO2 dissociation curve
  25. True or False: The CO2 dissociation curve is more linear and steeper than the 02 dissociation curve.
  26. Low P02 shifts the CO2 dissociation curve to the:

    (right or left)

    -more affinity for CO2
  27. High P02 shifts the CO2 dissociation curve to the:

    (right or left)

    -less affinity for CO2
  28. What is the Henderson-Hasslebalch equation and what does it describe?

    Describes: the pH resulting from the solution of CO2 in blood and the consequent dissociation of carbonic acid
  29. After manipulation the Henderson-Hasselbach equation can become a solution for finding pH. What is that equation?

    pKa- dissociation constant for a specific gas
  30. Respiratory Acidosis

    pH? PCO2? HCO3?
    Caused by increase in PCO2 (Co2 retention could be due to hypoventilation or ventilation/perfusion inequality)

    pH is decreased

    Compensatory mechanism: Raise HCO3! Kidneys conserve HCO3; usually not a complete compensation so pH usually doesnt return to 7.4
  31. Extent of renal compensation can be determined by:
    Base Excess: difference between new HCO3 and normal HCO3


    Base Deficit: negative base excess
  32. Respiratory Alkalosis

    pH? PCO2? HCO3?
    Caused by decrease in PCO2 (loss of CO2 could be caused by hyperventilation)

    pH is increased

    Compensatory mechanism: kidneys excrete more HCO3! After prolonged compensation, compensation may be nearly complete
  33. Metabolic Acidosis

    pH? PCO2? HCO3?
    Caused by decrease in HCO3 (could be from accumulation of acids in the blood like in uncontrolled diabetes or following release of lactic acid following tissue hypoxia)

    pH is decreased

    Compensatory mechanism: hyperventilation by lungs, decreases PCO2
  34. Metabolic Alkalosis

    pH? PCO2? HCO3?
    Caused by an increase in HCO3 (due to excessive ingestion of alkalis, loss of gastric acid secretion by vomiting)

    pH is increased

    Compensatory mechanism: possible reduction in alveolar ventilation (increasing PCO2)... respiratory compensation in metabolic alkalosis is usually small, sometimes absent
  35. An increase in carbon monoxide added to the blood would (increase/decrease) the 02 affinity of hemoglobin.