Differences In Feetal Circulation Vs. Postnatal Circulation

During pregnancy the cardiorespiratory system of the fetus adapts for survival in utero and then changes to an independent postnatal circulatory system. In order to understand the differences in fetal circulation versus postnatal circulation it is important to note that in a fully functioning not pregnant mammal blood circulates in the following way: vena cava, right atrium, tricuspid valve, right ventricle, pulmonary semi lunar valve, pulmonary arteries, lungs, pulmonary veins, left atrium, bicuspid valve, left ventricle, aortic semilunar valve, aorta, systemic circulation, vena cava. Fetal circulation works by using three shunts to direct deoxygenated blood and avoid the not yet fully developed lungs and liver. The patent foramen ovale …show more content…
The second shunt the ductus arteriosus protects the lungs against circulatory overload and allows the right ventricle to strengthen. The last shunt, the ductus venosus is a fetal blood vessel connecting the umbilical vein to the inferior vena cava. The ductus venosus carries mostly oxygenated blood and is regulated via a sphincter. . In addition, the placenta connects to the fetus via an umbilical cord, which is made up of the umbilical vein and the two umbilical arteries. Thus, there are several anatomical differences in utero versus postnatal. The differences account for the large difference in fetal circulation. Fetal circulation begins when the oxygenated blood from the placenta enters the fetus through the umbilical vein. The oxygenated blood then skips the liver due to the ductus venosus, shunt in left umbilical vein that is directly connected to the inferior vena cava, and mixes with …show more content…
The placenta does this by allowing transfer of oxygen and nutrients, in addition, to removing waste products and CO2. The fetus receives oxygen and nutrients due to trophoblasts that are imbedded in the chorionic plate. The chorionic plate sits right above the basal plate. The basal plate is connected to the uterus of the mother and is innervated by uterine veins and arteries that release red blood cells. Therefore, the trophoblasts reach into the area between the basal and chorionic plate so that diffusion of oxygen and nutrients can take place. In addition, CO2 diffuses out into the mother’s circulation. Fetus waste and CO2 can also be sent back to the mother’s circulation via the umbilical arteries and then the placenta. In addition to nutrients and oxygen, IgG antibodies can pass through the human placenta to provide protection to the fetus in utero. The IgG antibodies will begin to pass by the twentieth week of gestation and eventually provide the newborn baby with a basic immune