BRAINCAKEFetal Haemoglobin
A fetus gets its oxygen from its mother's blood at the placenta. The two blood supplies do not mix; oxygen must diffuse from the mother's haemoglobin, across the placenta, into the fetal blood. The pO2 in the placenta is quite low, so the fetus needs haemoglobin that can pick up oxygen there.
Fetal haemoglobin (HbF) has a higher affinity for oxygen than adult haemoglobin (HbA). It is made of two α chains and two γ (gamma) chains instead of two β (beta) chains. This slight difference in structure means it binds oxygen more readily.
As a result, the fetal oxygen dissociation curve lies to the left of the adult curve: at any given pO2, fetal haemoglobin is more saturated with oxygen than adult haemoglobin.
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More in Circulatory Systems
- Platelets
- Haemoglobin and Oxygen Transport
- Oxygen Dissociation Curve for Haemoglobin
- The Bohr Effect
- Myoglobin
- Transport of Carbon Dioxide
- Blood Clotting
- The Blood Clotting Cascade
All 33 lessons in Circulatory Systems · All Edexcel AS-level Biology topics