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In humans, the circulatory system is different before and after birth. The fetal circulation is composed of the placenta, umbilical blood vessels encapsulated by the umbilical cord, heart and systemic blood vessels. A major difference between the fetal circulation and postnatal circulation is that the lungs are not used during the fetal stage ...
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During fetal development, the foramen ovale allows blood to pass from the right atrium to the left atrium, bypassing the nonfunctional fetal lungs while the fetus obtains its oxygen from the placenta. A flap of tissue called the septum primum acts as a valve over the foramen ovale during that time.
The "E" series of prostaglandins are responsible for maintaining the openness of the ductus arteriosus (by dilation of vascular smooth muscle) throughout the fetal period. [3] Prostaglandin E2 (PGE 2 ), produced by both the placenta and the DA itself, is the most potent of the E prostaglandins, but prostaglandin E1 (PGE 1 ) also has a role in ...
In prenatal development, the eustachian valve helps direct the flow of oxygen-rich blood through the right atrium into the left atrium and away from the right ventricle. . Before birth, the fetal circulation directs oxygen-rich blood returning from the placenta to mix with blood from the hepatic veins in the inferior vena
A VSD can cause a left-to-right shunt of blood flow in the heart and is one of the most common of the congenital heart defects. This type of shunt is an acyanotic disorder that can result in ventricular hypertrophy. [4] The alignment of interventricular septum and interatrial septum is disturbed in various congenital heart diseases. [5]
The unpaired umbilical vein carries oxygen and nutrient rich blood derived from fetal-maternal blood exchange at the chorionic villi.More than two-thirds of fetal hepatic circulation is via the main portal vein, while the remainder is shunted from the left portal vein via the ductus venosus to the inferior vena cava, eventually being delivered to the fetal right atrium.
Umbilical cord compression can result from, for example, entanglement of the cord, [16] a knot in the cord, [16] or a nuchal cord, [16] (which is the wrapping of the umbilical cord around the fetal neck) [17] but these conditions do not always cause obstruction of fetal circulation. Velamentous cord insertion; Single umbilical artery; Umbilical ...