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Placenta - Anatomy & Physiology (view source)
Revision as of 13:56, 12 July 2011
, 13:56, 12 July 2011→Placental Blood Supply
* Endothelium of the fetal placental capillary in the teriary villus
* Endothelium of the fetal placental capillary in the teriary villus
===Placental Blood Supply===
===Placental Blood Supply===
Fetal blood enters the placenta via a pair of umbilical arteries which have numerous branches within the placenta to the chorionic plate. Oxygen and nutrient rich blood returns to the fetus via the umbilical vein. Maternal blood is supplied to the placenta via 80-100 spiral endometrial arteries which allow the blood to flow into intervillous spaces facilitating exchnage. The blood pressure within the spiral arteries is much higher than that found in the intervillous spaces resulting in more efficient nutrient exchange within the placenta.
Maternal blood carrying oxygen and nutrient substrate to the placenta must be transferred to the fetal compartment and this rate of transfer is the rate limiting step in the process. Therefore the placenta has a significant blood to facilitate improved exchange.
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Fetal blood enters the placenta via a pair of umbilical arteries which have numerous branches resulting in fetal chorionic villi within the placenta, terminating at the chorionic plate. The fetal chorionic villi are then surrounded by maternal tissues. This physiology is referred to as "invasive decidualisation" as the fetal chorionic villi effectively invade the maternal tissues. Invasive decidualisation is not present in pigs or sheep.
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Oxygen and nutrient rich blood returns to the fetus via the umbilical vein. Maternal blood is supplied to the placenta via 80-100 spiral endometrial arteries which allow the blood to flow into intervillous spaces facilitating exchnage. The blood pressure within the spiral arteries is much higher than that found in the intervillous spaces resulting in more efficient nutrient exchange within the placenta.
==Types of Placenta==
==Types of Placenta==