haemoglobin

Question 1

describe the role of haemoglobin

Answer 1

• present in red blood cells
• oxygen molecules bind to the haem groups and are carried around the body, then released where they are needed in respiring tissues

Question 2

how does partial pressure of oxygen affect oxygen-haemoglobin binding?

Answer 2

as partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases, so oxygen binds tightly to haemoglobin. when partial pressure is low, oxygen is released from haemoglobin

Question 3

what does oxyhaemoglobin dissociation curves show?

Answer 3

saturation of haemoglobin with oxygen (in %), plotted against partial pressure of oxygen (in kPa), curves further to left show the haemoglobin has a higher affinity for oxygen

Question 4

describe the Bohr effect

Answer 4

as partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape, the affinity of haemoglobin for oxygen therefore decreases, so oxygen is released from haemoglobin

Question 5

explain the role of carbonic anhydrase in the Bohr effect

Answer 5

• carbonic anhydrase is present in red blood cells
• converts carbon dioxide to carbonic acid, which dissociates to produce H+ ions
• these combine with the haemoglobin to form haemoglobinic acid
• encourages oxygen to dissociate from haemoglobin

Question 6

how does foetal haemoglobin differ from adult haemoglobin?

Answer 6

• the partial pressure of oxygen is low by the time it reaches the foetus, therefore foetal haemoglobin has a higher affinity for oxygen than adult
• allows both mother’s and child’s oxygen needs to be met