Haemoglobin

• Affinity: an attraction of one thing to another
• Bohr effect: a physiological phenomenon stating that haemoglobin's oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide
• Dissociation: The separation of one molecule from another
• Haemoglobin: globular protein in blood that readily combines with oxygen to transport it around the body. It comprises of four polypeptide chains around an iron-containing haem group
• Partial pressure: a measure of the concentration of a substance in a particular area
• Red blood cells contain haemoglobin
• Haemoglobin allows red blood cells to carry more oxygen that if it was only dissolved in the cytoplasm
• Each molecule of haemoglobin can transport 4 molecules of oxygen
• the saturation of haemoglobin depends upon the partial pressure of oxygen
• oxygen will bond to haemoglobin where there is a high ppO2
• haemoglobin will release oxygen when there is a low ppO2
• Dissociation curve is initially shallow as 'empty' haemoglobin makes it difficult for oxygen to bind
• there is a steep dissociation curve in the middle as the second and third oxygen molecules can easily bind
• the curve plateaus as the final oxygen molecule binds, it is difficult for this molecule to bind as the cell has changed shape so much
• haemoglobin has a higher affinity for co2 as it is dangerous for co2 to stay in the blood
• Co2 can bind and change the shape of haemoglobin
• when the haemoglobin's shape changes it has a lower affinity for oxygen
• co2 dissolves in water to form carbonic acid
• carbonic acid produces H+ ions, makes blood acidic
• decrease in pH denatures Hb, lower affinity for oxygen