The effect of fetal hemoglobin having a left shift on the O2-Hb curve is due to the fact that the fetal Hb has a greater affinity to the mother's oxygen and can leech it during gestation. It is similar to the effect of human placental lactogen (HPL), a hormone secreted by the placenta during pregnancy peaking at around 35-42 weeks. It stimulates insulin production but confers insulin resistance to the mother, thus shunting glucose to the baby. This can sometimes cause gestational diabetes if the mother cannot overcome insulin resistance. Both fetal Hb and HPL act to shunt resources to the baby, oxygen with fetal Hb, and glucose with HPL.
submitted by โshak360(19)
Increased concentrations of fetal hemoglobin results in a left shift of the oxygen dissociation curve with the maintenance of the sigmoidal cooperative binding characteristics.
I like to remember the "CADET!, stand RIGHT" mnemonic:
Factors that move the oxygen dissociation curve to the right are those physiological states where tissues need more oxygen. For example, during exercise, muscles have a higher metabolic rate, and consequently need more oxygen, produce more carbon dioxide and lactic acid, and their temperature rises (from Wikipedia on the O2-Hb dissociation curve).