| | Definition: | | This is the blood circulation in a fetus. It is distinct from newborn and adult circulation in the following aspects: - in fetal circulation, the cardiac output not only has to perfuse the body, but also the placenta (55% of output goes to the placenta).
- the umbilical cord connects the placenta to the fetus, blood from the fetal heart enters the placenta via the umbilical artery
- the umbilical vein contains oxygenated blood as versus the artery in newborn or adults containing oxygenated blood.
- there are two umbilical arteries and one umbilical vein.
- the pressure of the right heart chambers in the fetal circulation is higher than that of the left chambers, as a result, blood from right atrium passes through the foremen ovale to the left atrium, and blood from pulmonary artery passes through the ductus arteriosus to the aorta.
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