During pregnancy, the fetal circulatory system works in different ways than ~ birth:

The fetus is associated by the umbilical cord to the placenta, the body organ that develops and also 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 important nutrition, oxygen, and life assistance from the mother through the placenta.

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


The fetal circulatory system uses two ideal to left shunts, i m sorry are tiny passages that straight blood that needs to be oxygenated. The objective of this shunts is come bypass details body parts? in particular, the lungs and liver ? that room not fully developed when the fetus is tho in the womb. The shunts that bypass the lungs are called the foramen ovale, which moves blood from the right atrium of the heart to the left atrium, and also the ductus arteriosus, which move blood indigenous the pulmonary artery come the aorta.

Oxygen and nutrients indigenous the mother"s blood space transferred throughout the placenta come the fetus. The enriched blood flows with the umbilical cord come the liver and also splits right into three branches. The blood climate reaches the inferior vena cava, a significant vein connected to the heart. Many of this blood is sent through the ductus venosus, additionally a shunt the passes highly oxygenated blood with the liver come the worse vena cava and then come the ideal atrium that the heart. A small amount of this blood goes straight to the liver to give it the oxygen and nutrients that 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 chamber on the upper right side that the heart. Once the blood beginning the ideal atrium, many of that flows v the foramen ovale right into the left atrium.

Blood then passes right into the left ventricle (lower chamber of the heart) and also then come the aorta, (the huge artery comes from the heart).

From the aorta, blood is sent to the heart muscle itself in enhancement to the brain. After circulating there, the blood returns to the right atrium the the heart through the exceptional vena cava. About two thirds of the blood will certainly pass with the foramen ovale as explained above, but the remaining one third will pass into the ideal ventricle, toward the lungs.

In the fetus, the placenta walk the work of breathing rather of the lungs. Together a result, just a tiny amount that the blood proceeds on to the lungs. Many of this blood is bypassed or shunted far from the lungs through the ductus arteriosus come the aorta. Most of the circulation to the lower body is offered by blood passing through the ductus arteriosus.

This blood then enters the umbilical arteries and also flows right into the placenta. In the placenta, carbon dioxide and waste assets are released right 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 infant no longer receives oxygen and nutrients from the mother. With the first breaths that life, the lungs start to expand. Together the lung expand, the alveoli in the lungs are cleared of fluid. An increase in the baby"s blood pressure and a significant reduction in the pulmonary pressure reduces the require for the ductus arteriosus come shunt blood. These transforms promote the closure of the shunt. These alters increase the press in the left atrium of the heart, i m sorry decrease the push in the ideal 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 transition of fetal circulation to newborn circulation.