During pregnancy, the fetal circulatory device works differently than after ~ birth:

The fetus is associated by the umbilical cord to the placenta, the organ that develops and implants in the mother"s uterus throughout pregnancy.

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Through the blood ship in the umbilical cord, the fetus receives all the crucial nutrition, oxygen, and also life support from the mom through the placenta.

Waste products and carbon dioxide indigenous the fetus space sent ago through the umbilical cord and also placenta come the mother"s circulation to it is in eliminated.


The fetal circulatory system uses two appropriate to left shunts, i m sorry are little passages that direct blood that demands to be oxygenated. The purpose of this shunts is come bypass specific body parts? in particular, the lungs and also liver ? that are not totally developed when the fetus is tho in the womb. The shunts the bypass the lungs are dubbed the foramen ovale, which move blood from the right atrium that the love to the left atrium, and also the ductus arteriosus, which move blood from the pulmonary artery come the aorta.

Oxygen and also nutrients from the mother"s blood space transferred across the placenta to the fetus. The enriched blood flows v the umbilical cord to the liver and splits into three branches. The blood climate reaches the inferior vena cava, a major vein connected to the heart. Many of this blood is sent out through the ductus venosus, additionally a shunt that passes highly oxygenated blood v the liver come the inferior vena cava and also then come the appropriate atrium that the heart. A tiny amount the this blood goes directly to the liver to provide it the oxygen and nutrients it needs.

Waste commodities from the fetal blood room transferred back throughout the placenta to the mother"s blood.

Inside the fetal heart:

Blood enters the ideal atrium, the chamber on the upper right side that the heart. As soon as the blood beginning the best atrium, most of the flows v the foramen ovale into the left atrium.

Blood then passes into the left ventricle (lower chamber of the heart) and then to the aorta, (the big artery comes 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 the the heart with the premium vena cava. About two thirds of the blood will pass with the foramen ovale as described above, yet the remaining one third will pass into the appropriate ventricle, towards the lungs.

In the fetus, the placenta does the work-related of breathing rather of the lungs. Together a result, only 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. Most of the circulation to the lower body is offered by blood passing with the ductus arteriosus.

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

At birth, the umbilical cord is clamped and the baby no much longer receives oxygen and also nutrients indigenous the mother. With the first breaths of life, the lungs begin to expand. As the lung expand, the alveoli in the lungs room cleared that fluid. An increase in the baby"s blood pressure and also a significant reduction in the pulmonary pressure reduces the need for the ductus arteriosus to shunt blood. These changes promote the closure of the shunt. These transforms increase the push in the left atrium of the heart, i m sorry decrease the pressure in the right atrium. The change in push stimulates the foramen ovale to close.

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