CO2

• what are the three ways to transport CO2 around the body?

  blood plasma

  attaching to haemoglobin (carbominohaemoglobin)

  carbonic acid
• gas exchange at respiring tissues:

  • dissolved CO2 goes into blood plasma
  • In RBC:
  • CO2 + Hb --> HbCO2
  • CO2 + H2O --(CAH)--> H2CO3 --> HCO- + H+
  • O2 + HHb <-- HbO2
• gas exchange at respiring tissues:

  CO2 + H2O --(CAH)--> H2CO3 --> HCO- + H+

  • CAH = catalyst and requires a cofactor to work (zinc)
  • HCO- = leaves the RBC
  • chloride ion enters
  • pH decreases (acidity decreases), H+ concentration increases
• Chloride shift: replaces ions lost to keep the charge stable
• gas exchange at respiring tissues:

  O2 + HHb <-- HbO2

  • less affinity for oxygen
  • haemoglobic acid