Transport of carbon dioxide

• What are the 3 ways that carbon dioxide is transported through the circulatory system?

  -dissolved in plasma (5%)

  -associated with haemoglobin to form carbamino-haemoglobin (10%)

  -transported as hydrogen carbonate ions (85%)
• Explain how CO2 gets transported as hydrogen carbonate ions.?

  1. CO2 diffuses into RBC
  2. CO2 dissolves in water to form carbonic acid (with a carbonic anhydrase catalyst)
  3. Carbonic acid disassociates into H+ ions and hydrogen carbonate ions (HCO3-)
  4. HCO3- ions diffuse out of the RBC into the plasma via facilitated diffusion
  5. To balance the outflow of negative charge, chloride ions (Cl-) diffuse into the cell. This is called chloride shift.