Placental Oxygen Gradients Due to Diffusion and Chemical Reaction
This paper is a report of preliminary computations showing that gradients of oxygen tension are likely to exist in the human placenta due to slowness of oxygen equilibration between maternal and fetal blood. Calculations of likely gradients have been recently made by Hill, Power, and Longo (3) using a placental model in which blood flow was of the concurrent pattern, that is to say maternal and fetal capillaries ran together for a distance and the flow was in the same direction in each. These workers found that there was very little tension gradient if the capillary transit time in each circulation was taken as 1.7 seconds. The calculations whose results are presented in this paper differ from those of Hill et al (3) in two important respects; firstly they consider not only the concurrent model of the placenta but also a pool model and the multivillous stream system model, and secondly they use recently determined results for oxygen reaction rates with partly saturated human adult and fetal red cells.
KeywordsOxygen Tension Human Placenta Fetal Blood Full Equilibration Placental Membrane
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