During pregnancy, the fetal circulatory device works in different way than ~ birth:

The fetus is linked by the umbilical cord come the placenta, the organ that develops and implants in the mother"s uterus during pregnancy.

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Through the blood vessels in the umbilical cord, the fetus receives every the crucial nutrition, oxygen, and life assistance from the mommy through the placenta.

Waste products and carbon dioxide from the fetus are sent earlier through the umbilical cord and also placenta to the mother"s circulation to it is in eliminated.


The fetal circulatory device uses two ideal to left shunts, i m sorry are small passages that direct blood that needs to be oxygenated. The function of these shunts is to bypass specific body parts? in particular, the lungs and also liver ? that room not completely developed when the fetus is quiet in the womb. The shunts that bypass the lung are referred to as the foramen ovale, which move blood native the appropriate atrium the the love to the left atrium, and also the ductus arteriosus, which move blood indigenous the pulmonary artery to the aorta.

Oxygen and also nutrients native the mother"s blood are transferred across the placenta to the fetus. The enriched blood flows with the umbilical cord to the liver and also splits right into three branches. The blood then reaches the worse vena cava, a major vein linked to the heart. Many of this blood is sent through the ductus venosus, also a shunt the passes very oxygenated blood with the liver come the worse vena cava and then to the best atrium of the heart. A tiny amount the this blood goes directly to the liver to offer it the oxygen and also nutrients it needs.

Waste assets from the fetal blood room transferred back across the placenta to the mother"s blood.

Inside the fetal heart:

Blood enters the appropriate atrium, the room on the upper appropriate side that the heart. When the blood start the ideal atrium, most of that flows v the foramen ovale right into the left atrium.

Blood climate passes into the left ventricle (lower chamber of the heart) and then to the aorta, (the large artery coming from the heart).

From the aorta, blood is sent out to the heart muscle itself in addition to the brain. After circulating there, the blood returns to the right atrium that the heart with the premium vena cava. About two thirds of the blood will pass with the foramen ovale as defined above, but the staying one 3rd will pass right into the appropriate ventricle, toward the lungs.

In the fetus, the placenta go the work-related of breathing rather of the lungs. Together a result, just a tiny amount of the blood proceeds on to the lungs. Many of this blood is bypassed or shunted away from the lungs through the ductus arteriosus to the aorta. Many of the circulation come the lower body is supplied by blood passing v the ductus arteriosus.

This blood then enters the umbilical arteries and flows into the placenta. In the placenta, carbon dioxide and waste commodities are released into the mother"s circulatory system, and oxygen and also nutrients from the mother"s blood are released right into the fetus" blood.

At birth, the umbilical cord is clamped and also the infant no longer receives oxygen and also nutrients from the mother. With the an initial breaths of life, the lungs start to expand. As the lungs expand, the alveoli in the lungs room cleared that fluid. An increase in the baby"s blood pressure and also a far-ranging reduction in the pulmonary pressures reduces the need for the ductus arteriosus to shunt blood. These changes promote the closure that the shunt. These alters increase the push in the left atrium the the heart, which decrease the pressure in the ideal atrium. The shift in pressure stimulates the foramen ovale to close.

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The closure the the ductus arteriosus and foramen ovale completes the change of fetal circulation to newborn circulation.