Transport of Carbon Dioxide AS Biology Module 2 Lesson 12 CRD

Objectives By the end of the lesson you should be able to: Describe the role of haemoglobin in carrying carbon dioxide Describe and explain the significance of the dissociation curves of adult oxhaemoglobin at different carbon dioxide levels (the Bohr effect)‏

By the end of the lesson you should be able to:

Describe the role of haemoglobin in carrying carbon dioxide

Describe and explain the significance of the dissociation curves of adult oxhaemoglobin at different carbon dioxide levels (the Bohr effect)‏

Terminology haemoglobin oxyhaemoglobin carbaminohaemoglobin haemoglobinic acid

How is Carbon Dioxide transported 5% in the plasma 10% combined with haemoglobin (carbaminohaemoglobin)‏ 85% as hydrogencarbonate ions (HCO 3 - )‏

5% in the plasma

10% combined with haemoglobin (carbaminohaemoglobin)‏

85% as hydrogencarbonate ions (HCO 3 - )‏

Formation of Hydrogencarbonate ions Some carbon dioxide enters red blood cells Combines with water to form carbonic acid (enzyme carbonic anhydrase)‏ Carbonic acid dissociates to release hydrogen ions and hydrogen carbonate ions. Hydrogen carbonate ions diffuse out of rbc and into plasma. Charge maintained by chloride entering the rbc (called chloride shift)‏ Hydrogen ions combine with haemoglobin to form haemoglobinic acid.

Some carbon dioxide enters red blood cells

Combines with water to form carbonic acid (enzyme carbonic anhydrase)‏

Carbonic acid dissociates to release hydrogen ions and hydrogen carbonate ions.

Hydrogen carbonate ions diffuse out of rbc and into plasma.

Charge maintained by chloride entering the rbc (called chloride shift)‏

Hydrogen ions combine with haemoglobin to form haemoglobinic acid.

Formation of Hydrogencarbonate ions

Releasing oxygen The partial pressure of oxygen (also called oxygen tension) of respiring tissues is lower than the lungs. Oxyhaemoglobin dissociates.

The partial pressure of oxygen (also called oxygen tension) of respiring tissues is lower than the lungs.

Oxyhaemoglobin dissociates.

Bohr Effect Hydrogen ions compete with oxygen and displace oxygen on haemoglobin. Oxyhaemoglobin releases more oxygen.

Hydrogen ions compete with oxygen and displace oxygen on haemoglobin.

Oxyhaemoglobin releases more oxygen.