Final answer:
Fetal hemoglobin binds oxygen with greater affinity than adult hemoglobin due to structural differences and lower interactions with 2,3-BPG. This allows more effective oxygen uptake by the fetus from the maternal blood across the placenta.
Step-by-step explanation:
Fetal hemoglobin binds oxygen with greater affinity than adult hemoglobin. The differences in structure between fetal and adult hemoglobin contribute to this variation in oxygen-binding capacity. The presence of 2,3-bisphosphoglycerate (2,3-BPG) in red blood cells is one factor that can influence hemoglobin's oxygen affinity. Adult hemoglobin interacts more with 2,3-BPG which decreases its affinity for oxygen. However, fetal hemoglobin has a lower binding affinity for 2,3-BPG, allowing it to more effectively bind oxygen even at the lower partial pressures found in the fetal blood supply. This adaptation is crucial for the fetus to attract oxygen from the maternal blood supply across the placenta.
In the oxygen-hemoglobin dissociation curve, which depicts the relationship of oxygen binding, fetal hemoglobin curves lie to the left of adult hemoglobin curves, indicating that fetal hemoglobin binds oxygen more readily. This is essential because the partial pressure of oxygen in the placental blood is lower than in maternal arterial blood. The greater affinity for oxygen by fetal hemoglobin ensures efficient oxygen transfer from the mother to the fetus.