Blood Transport

Question 1

Arterial Oxygen Content

Answer 1

• 1- Dissolved Oxygen (poorly dissolves in plasma)
• 2- Combined w/ Hemoglobin (majority)
  
  • Cooperative binding
• CaO2 = (1.34 x [Hb] x %sat) + (.003 x PaO2)
  
  • BUT .003 x PaO2 is so small that it can be ignored

Question 2

Total O2 Delivery Equation

Answer 2

Total O2 Delivery = CaO2 x CO x 10 = 1.34 x [Hb] x % sat (as fraction) x CO x 10

**Dec in CO and [Hb] has greater effect than dec in CaO2 at near normal levels

Question 3

What causes shifts in Hb-Oxygen Dissociation Curve

Answer 3

• Shifts R if… (reduced affinity) …RIGHT RELEASE/RIGHT REDUCED
  
  • High 2,3-DPG, low pH (higher CO2, lactic acidosis), higher temp
• Shifts L if… (larger affinity) …LEFT LATCH ON/LEFT LARGER
  
  • Low 2,3-DPG, high pH, lower temp

Question 4

Arterial CO2 Content

Answer 4

• Small amount in plasma
  
  • 1- Small amount dissolved in plasma (.067 x pCO2)
  • 2- Bound by plasma proteins –> carbamino compounds
  • 3- Some hydrated –> H2CO3 –> H+ and HCO3- (SLOW b/c no carbonic anhydrase in plasma)
• Most enters RBCs
  
  • 1- Small amount dissolved in RBC
  • 2- Combine directly w/ Hb –> carbamino groups (NH3 groups of Hb binds w/ CO2)
  • 3- Carbonic anhydrase in RBCs –> H+ and HCO3-
    
    • HCO3- moves out of RBC in exchange for Cl-
    • Hb binds the new H+ (buffer) –> Bohr effect

Question 5

Bohr Effect

Answer 5

• when Hb binds H+ as buffer –> dec affinity of Hb for O2
• shifts dissociation curve to R –> more O2 off-loading
• Facilitates oxygen delivery to TISSUES
• Conc of CO2 effects O2 saturation

Question 6

Haldane Effect

Answer 6

• deoxygenated Hb has greater affinity for CO2
• So when you oxygenate the Hb at the LUNGS w/ new O2 supply - it facilitates CO2 off-loading by dec Hb’s affinity for CO2
• O2 saturation effects CO2 conc