Fetal haemoglobin

Question 1

Fetal haemoglobin

Answer 1

Fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin –
therefore, steeper dissociation curve. This is because fetal haemoglobin
must be able to associate with oxygen in an environment where the pO2 is
low enough to make the adult haemoglobin dissociate with oxygen.
Oxygen saturation is low in the mother’s blood at the placenta, as oxygen
has been used up by the body. In the placenta, as pO2 is low, fetal
haemoglobin will bind with oxygen in the surrounding fluid, reducing oxygen
tension and making oxygen diffuse out of the mother’s blood (down conc gradient). This reduces pO2 within the mother’s blood, making it dissociate with more oxygen.