Oxygen Transport in Blood: Hemoglobin

1. Association & Dissociation of Oxygen + Hemoglobin
1. oxyhemoglobin (HbO2) - oxygen molecule bound
2. deoxyhemoglobin (HHb) - oxygen unbound
• H-Hb + O2 <========> HbO2 + H+
3. binding gets more efficient as each O2 binds
4. release gets easier as each O2 is released
5. Several factors regulate AFFINITY of O2
• Partial Pressure of O2
• temperature
• blood pH (acidity)
• concentration of "diphosphoglycerate" (DPG)
2. Effects of Partial Pressure of O2
1. oxygen-hemoglobin dissociation curve
• 104 mm (lungs) - 100% saturation (20 ml/100 ml)
• 40 mm (tissues) - 75% saturation (15 ml/100 ml)
• right shift - Decreased Affinity, more O2 unloaded
• left shift - Increased Affinity, less O2 unloaded
3. Effects of Temperature
1. HIGHER Temperature -----> Decreased Affinity (right)
2. LOWER Temperature -----> Increased Affinity (left)
4. Effects of pH (Acidity)
1. HIGHER pH ------> Increased Affinity (left)
2. LOWER pH ------> Decreased Affinity (right) "Bohr Effect"
• more Carbon Dioxide, lower pH (more H+), more O2 release
5. Effects of Diphosphoglycerate (DPG)
1. DPG - produced by anaerobic processes in RBCs
2. HIGHER DPG ----------> Decreased Affinity (right)
3. thyroxine, testosterone, epinephrine, NE - increase RBC metabolism and DPG production, cause RIGHT shift
6. Oxygen Transport Problems
1. hypoxia - below normal delivery of Oxygen
• anemic hypoxia - low RBC or hemoglobin
• stagnant hypoxia - impaired/blocked blood flow
• hypoxemic hypoxia - poor lung gas exchange
2. carbon monoxide poisoning - CO has greater Affinity than Oxygen or Carbon Dioxide
   

Category: Physiology Notes