Fetal circulation, the blood generalized by oxygen comes from a placenta through a venous (arantia) channel in the bottom. the vena cava of the fetus and mixed there with venous blood coming from the bottom. parts of the body. Due to the presence in the right atrium of the Eustachian valve, most of this blood is directed through the oval window into the left atrium, the left ventricle, then into the aorta and through the subclavian arteries to the head and upper limbs.
Venous blood flowing from the top, half of the body enters the right ventricle, then into the pulmonary artery and arterial duct, and from there to the descending aorta. In this regard, the brain and the liver receive the most oxygen-rich blood. After the baby is born, by the end 2 week of life, the venous duct and umbilical vessels are transformed into a round ligament of the liver and hepatoumbilical ligaments, respectively.The arterial duct and the oval window are closed for 6-8 weeks, and sometimes for 3-4 months of life.
SCHEMATIC IMAGE OF FRUIT CIRCULATION (a):
SCHEMATIC IMAGE OF CIRCULATION IN THE NEWBORN (b):