Please confirm topic selection

Are you sure you want to trigger topic in your Anconeus AI algorithm?

Please confirm action

You are done for today with this topic.

Would you like to start learning session with this topic items scheduled for future?

Updated: May 25 2021

Oxygen-Hemoglobin Dissociation Curve

  • Overview
    • Oxygen-hemoglobin dissociation curve
      • sigmoidal shape is characteristic of positive cooperativity
        • binding of 1 O2 molecule to 1 subunit of deoxyhemoglobin increases affinity for O2 in adjacent subunits
      • P50 is PO2 at which hemoglobin is 50% saturated
        • ↑ P50 → ↓ hemoglobin affinity for O2
          • 50% saturation achieved at higher-than-normal P50
        • ↓ P50 → ↑ hemoglobin affinity for O2
          • 50% saturation achieved at lower-than-normal P50
    • Loading and unloading of oxygen
      • in lungs
        • PaO2 ≈ 100 mm Hg
        • hemoglobin % saturation ≈ 100%
        • facilitates maximal O2 loading into arterial blood in lungs
      • in peripheral tissues
        • PvO2 ≈ 40 mm Hg
        • hemoglobin % saturation ≈ 75%
        • facilitates O2 unloading into peripheral tissues
    • Shift to right
      • mechanism
        • ↑ P50 → ↓ hemoglobin affinity for O2 → ↑ O2 unloading
      • causes
        • ↑ PCO2, ↓ pH (Bohr Effect)
          • ↑ PCO2 → ↑ H+ → ↓ pH
            • CO2 + H2O → H2CO3 → H+ + HCO3-
              • ↑ PCO2 → equilibrium reaction shifts right
                • Le Chatelier's principle
          • ↑ CO2, ↑ H+ bind hemoglobin and stabilize low O2 affinity T (taut) state
            • ↓ hemoglobin affinity for O2 → ↑ O2 unloading
              • e.g., exercise → ↑ PCO2, ↓ pH
                • ↑ O2 unloading ensures O2 delivery meets O2 demand in skeletal muscle
        • ↑ temperature
          • e.g., ↑ tissue metabolism → ↑ temperature
        • ↑ 2,3-bisphosphoglycerate (2,3-BPG)
          • high altitude → hypoxemia → ↑ synthesis of 2,3-BPG
            • Also seen in heart failure, anemia, morbid obesity, etc.
          • ↑ 2,3-BPG binds hemoglobin and stabilizes low O2 affinity T (taut) state
            • ↓ hemoglobin affinity for O2 → ↑ O2 unloading
    • Shift to left
      • mechanism
        • ↓ P50→ ↑ hemoglobin affinity for O2 → ↓ O2 unloading
      • causes
        • ↓ PCO2, ↑ pH (Bohr Effect)
          • ↓ PCO2 → ↓ H+ → ↑ pH
          • ↓ CO2, ↓ H+ → stabilizes high O2 affinity R (relaxed) state
            • ↑ hemoglobin affinity for O2 → ↑ O2 loading
          • conversely, ↑ O2 decreases Hb affinity for CO2/H (Haldane effect)
        • ↓ temperature
          • ↓ tissue metabolism → ↓ temperature
        • ↓ 2,3-bisphosphoglycerate (2,3-BPG)
        • hemoglobin F
          • fetal hemoglobin
          • 2 α subunits and 2 γ subunits (α2γ2)
            • ↑ affinity for O2, ↓ affinity for 2,3-BPG
              • facilitates O2 delivery from mother to fetus
Card
1 of 0
Question
1 of 1
Private Note