5B - Gas Transport and Ventilation/Perfusion Ratios Flashcards
What are the two forms that oxygen is carried in the blood?
- Bound to hemoglobin (~98.5% - most important)
2. Dissolved in plasma (~1.5%)
Normal adult hemoglobin is comprised of what subunits?
What state is iron in to bind O2?
a2b2
Ferrous state (Fe2+)
5b6. Hemoglobin-O2 Dissociation Curve
Arterial blood has a P(O2) of 100 mmHg. What is the level of oxygen saturation of hemoglobin at this point?
Hemoglobin is 98-100% saturated - Oxygen bound to all four heme groups on all hemoglobin molecules
5b6. Hemoglobin-O2 Dissociation Curve
Mixed venous blood has a P(O2) of 40 mmHg. What is the level of oxygen saturation of hemoglobin at this point?
Hemoglobin is 75% saturated - on average, 3 of the 4 heme groups on each hemoglobin have O2.
5b7. Hemoglobin-O2 Dissociation Curve
What is the level of oxygen saturation of hemoglobin at P(O2) of ~25 mmHg?
Hemoglobin is 50% saturated - on average, 2 of the 4 heme groups of each hemoglobin molecule have O2 bound
5b8. What is the shape of the hemoglobin-O2 dissociation curve? What do you call the relationship between PO2 and hemoglobin saturation? (what kind of cooperativity)?
Sigmoid shape
Positive cooperativity
5b10. What factors influence hemoglobin saturation at a given PO2?
P(CO2)
pH
Temperature
2,3-BPG Hemoglobin F
5b11. When will the hemoglobin-O2 dissociation curve shift to the right?
Increased P(CO2), decreased pH, increased temperature, or increased 2,3-BPG
5b11. When the hemoglobin-O2 dissociation graph shifts to the right, what does it mean for O2 unloading and for % saturation of hemoglobin?
O2 unloading from the arterial blood to tissues if facilitated
% saturation of hemoglobin is decreased
5b12. How does exercise affect the Hemoglobin-O2 dissociation curve?
Shifts to the right
- More CO2 produced
- Tissue pH decreased
- Temperature increased
- 2,3-DPG concentration incresaed
- Stimulates O2 delivery to exercising muscles
5b14. What is an adaptation that the body makes in reaction to chronic hypoxemia (living at high altitude)?
Increased synthesis of 2,3-BPG, which binds to hemoglobin and facilitates unloading of O2 in the tissues
5b16. What changes can trigger a hemoglobin-O2 dissociation curve shift to the left?
Decreased P(CO2)
Increased pH
Decreased temperature
Decreased 2,3-BPG concentration
5b15. When the hemoglobin-O2 dissociation curve shifts to the left, is unloading O2 from arterial blood to the tissues more or less difficult?
More difficult
At any level of P02 - the % saturation of hemoglobin is increased
5b17. Which has a higher affinity for hemoglobin - CO or O2?
CO has a 200x affinity for hemoglobin than does O2
CO will occupy O2 binding sites on hemoglobin and decrease the O2 concentration of blood.
5b17. Will binding of CO shift the curve to the left or right?
CO will shift the curve to the left, increasing the affinity of the remaining site for O2.