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a) The oxygen dissociation curve of fetal haemoglobin is shifted to the left The fetal circulation supplies the fetal tissues with oxygen and. The fetal circulation (Fig. 1) is markedly different from the adult circulation. In the fetus, gas exchange does not occur in the lungs but in the placenta. Blood flow;. Fetus;. Placenta;. Ductus venosus;. Ductus arteriosus;. Foramen ovale;. Liver developing circulation, with both short- and long-term implications.

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Fetal Circulation Pdf

Facilitates gas, nutrient, and waste exchange between maternal and fetal blood. □ Maternal and fetal blood do not mix, though certain cells pass (i.e. T-cells). Different segments of fetal circulation. -Placenta – pulmonary circulation. • Developmental changes. • Transition at birth. Function of Circulatory System. • Provide. In animals that give live birth, the fetal circulation is the circulatory system of a fetus. The term .. Print/export. Create a book · Download as PDF · Printable version.

The publisher's final edited version of this article is available at Clin Perinatol See other articles in PMC that cite the published article. Abstract The physiology of the fetus is fundamentally different from the neonate with both structural and functional distinctions. The fetus is well-adapted to the relatively hypoxemic intrauterine environment. The transition from intra- to extrauterine life requires rapid, complex and well-orchestrated steps to ensure neonatal survival. This chapter explains intrauterine physiology that allows the fetus to survive and then reviews the physiologic changes that occur during the transition to extrauterine life. Asphyxia fundamentally alters the physiology of transition and necessitates a thoughtful approach in the management of affected neonates. Keywords: fetal physiology, intrauterine circulation, transition from intrauterine to extrauterine life, transition physiology Introduction The physiology of the fetus is fundamentally different from the neonate with both structural and functional distinctions. It is critical that neonatal care providers have a clear understanding of fetal and normal transitional physiology so that they can recognize deviations from typical physiology and appropriately manage these scenarios 1. Fetal Physiology Cardiac Development The human fetal circulation begins when the heart first beats at approximately 22 days of gestation. Because oxygenated maternal blood mixes with poorly oxygenated blood within the free-flowing placental space, the oxygen content of blood provided to the fetus is lower than the maternal uterine arterial blood, causing the fetus to live in a relatively hypoxemic environment. As the fetal lungs do not contribute to intrauterine oxygenation, there are several intrauterine shunts designed to direct blood away from the fetal lungs. Unique aspects of the fetal circulation and other organ systems are summarized in Table 1.

Oxygen then diffuses from the placenta to the chorionic villus, an alveolus -like structure, where it is then carried to the umbilical vein. Diagram of the human fetal circulatory system.

The circulatory system , consisting of the heart and blood vessels, forms relatively early during embryonic development, and continues to develop in complexity within the growing fetus. A functional circulatory system is a biological necessity, since mammalian tissues can not grow more than a few cell layers thick without an active blood supply.

The prenatal circulation of blood is different than the postnatal circulation, mainly because the lungs are not in use.

Fetal circulation - Wikipedia

The fetus obtains oxygen and nutrients from the mother through the placenta and the umbilical cord. About half of this enters the fetal ductus venosus and is carried to the inferior vena cava , while the other half enters the liver proper from the inferior border of the liver.

In the fetus, there is an opening between the right and left atrium the foramen ovale , and most of the blood flows from the right into the left atrium, thus bypassing pulmonary circulation.

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The majority of blood flow is into the left ventricle from where it is pumped through the aorta into the body. Some of the blood moves from the aorta through the internal iliac arteries to the umbilical arteries, and re-enters the placenta, where carbon dioxide and other waste products from the fetus are taken up and enter the woman's circulation.

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In the fetus, there is a special connection between the pulmonary artery and the aorta, called the ductus arteriosus , which directs most of this blood away from the lungs which aren't being used for respiration at this point as the fetus is suspended in amniotic fluid.

This leads to the closure of the foramen ovale , which is then referred to as the fossa ovalis.

Blood Circulation in the Fetus and Newborn How does the fetal circulatory system work? The unborn baby is connected to the placenta by the umbilical cord. While the baby is still in the uterus, his or her lungs are not being used.

The fetal circulation

Circulating blood bypasses the lungs and liver by flowing in different pathways and through special openings called shunts. Blood flow in the unborn baby follows this pathway: Oxygen and nutrients from the mother's blood are transferred across the placenta to the fetus through the umbilical cord.

There it moves through a shunt called the ductus venosus. This allows some of the blood to go to the liver.

Fetal circulation

But most of this highly oxygenated blood flows to a large vessel called the inferior vena cava and then into the right atrium of the heart. Here is what happens inside the fetal heart: When oxygenated blood from the mother enters the right side of the heart it flows into the upper chamber the right atrium.

Most of the blood flows across to the left atrium through a shunt called the foramen ovale. From the left atrium, blood moves down into the lower chamber of the heart the left ventricle.

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