The fetal circulation is arranged to allow oxygenrich blood from the placenta to initially flow to the liver, where it divides to either the portal sinus or ductus venosus and then enters the right atrium via the inferior vena cava. Fetal circulation congenital heart defects simplified. Fetal circulation an overview sciencedirect topics. It is active by the beginning of the fourth week when the placenta is unable to meet the requirements of the growing embryo. Waste products from the fetal blood are transferred back across the placenta to the mothers blood. The bulk of this blood passes through the foramen ovale, into the left atrium. Blood circulation in the fetus and newborn childrens. The arterial oxygenation of this blood is approximately 25 to 28 mm hg. Fetal blood sampling was undertaken to exclude anemia, infection, and metabolic abnormalities, after which, ivig 1 gkg, with an estimated fetal weight of 1.
When blood goes through the placenta it picks up oxygen. Jun 30, 2017 a visual explanation of fetal circulation and how it differs from that of postnatal or adult circulation. I love creating resources to help medical students with their studies. Apr 10, 2020 fetal blood vessels and fetal circulation. Vascular structures formed early in gestation provide an initial platform for gas exchange and nutrient delivery. It then passes into the inferior vena cava and enters the right atrium. Specialized circulatory structures required for systemic circulation then form later in gestation to support the metabolic needs of the fetus before. During an intrauterine period, the fetus develops own blood cells and circulatory system, but the oxygen and nutrients are obtained from the placenta through diffusion, osmosis, and active transport method.
There are four temporary structures in fetal circulation. The three shunts, ductus venosus, ductus arteriosus and foramen ovale, are essential distributional arrangements, making the fetal circulation a. Discuss fetal anatomy discuss the fetal circulation course of the circulation admixture of oxygenated and systemic venous blood fetal vascular pressures blood gases and oxygen saturation cardiac output and its distribution birth associated changes in circulation. Mar 26, 20 fetal circulation foramen ovale small opening in the septum of the heart completely bypasses the nonfunctioning lungs blood continues journey to the left ventricle blood is then pumped into the aorta blood is circulated to the upper extremities blood then returns to the right atrium. This means that a fetus can steal oxygen from its mothers blood. Fetal circulation is an umbrella term for the circulatory system through which blood and lymph flow throughout the body of the unborn baby and comprises of heart, blood vessels, blood, and lymph and the placental system which includes the birth cord and the blood vessels in the placenta that carry blood to and from the fetus. Two umbilical arteries carry oxygendepleted fetal blood, including wastes and carbon dioxide, to the placenta. It is essential that we learn the true nature of the fetal circulation to understand changes occurring at birth. The uncoiling of the fetal pulmonary blood vessels results in a sudden considerable fall in pulmonary vascular resistance, while at the same time the systemic circulation increases. Dec 21, 2004 accumulating data on the human fetal circulation shows the similarity to the experimental animal physiology, but with important differences. Aug 08, 2016 poorly oxygenated and nutrientpoor fetal blood is sent back to the placenta via right and left umbilical arteries. About half of this blood passes through the hepatic capillaries and the rest flows through the ductus.
The umbilical vein receives nutrients and oxygen from the mothers circulation and transports them to the fetal circulation. Congenital cardiovascular malformations and the fetal. Fetal circulation by lisa mccabe for openpediatrics. A small amount of this blood goes directly to the liver to give it the oxygen and nutrients it needs. Normal fetal circulation and cardiovascular adaptations at. Prior to birth the foetus is not capable of respiratory function and thus relies on the maternal circulation to carry out gas, nutrient and waste exchange. Two different shunts are used to reroute blood from the lungs. Blood enters the right atrium, the chamber on the upper right side of the heart. During pregnancy, the fetal circulatory system works differently than after birth. Fetal circulation the blood that flows through the fetus is actually more complicated than after the baby is born normal heart. The oxygen rich blood goes through one of the two extra connections in the fetal heart that will close after the baby is born.
A flexible cordlike structure containing blood vessels and attaching a human to the placenta responsible for the supplying and elimination of co2 and o2. The term usually encompasses the entire fetoplacental circulation, which includes the umbilical cord and the blood vessels within the placenta that carry fetal blood the fetal prenatal circulation differs from normal postnatal circulation, mainly because the lungs are not in use. Physiology of the fetal circulation and growth, with a gradual return towards normal concentrations of blood gases and endocrine status,80 although with a residual deviation that may have a longlasting effect on fetal and newborn life. Embryology, fetal circulation statpearls ncbi bookshelf. At the time of birth, multiple changes occur to transition from fetal circulation to infant circulation.
The fetal circulation kiserud 2004 prenatal diagnosis. Newborn adaptation to extrauterine life and newborn assessment. Blood gases and acidbase status of the human secondtrimester fetus. The fetus is connected by the umbilical cord to the placenta. The umbilical arteries carry deoxygenated blood from the whole body to the placenta which is the gaseous exchange. Fetal circulation differs from adult circulation in a variety of ways to support the unique physiologic needs of a developing fetus. Most of the circulation to the lower body is supplied by blood passing through the ductus arteriosus. The circulation of oxygenated blood, deoxygenated blood, nutritive material etc in the foetus is termed as foetal circulation. Investigating fetal cord blood during delivery is beneficial for. The partial pressure of oxygen po2 in the umbilical vein is around 4. Circulation of blood systemic and pulmonary circulation blood circulation refers to the flow of blood through all the vessels, which are arranged in a complete circuit or circular pattern systemic circulation carries blood throughout the body path goes from left ventricle through aorta. The prenatal circulation is different from postnatal circulation after the fetus is disconnected with the umbilical vessels. Blood circulation in the fetus and newborn how does the fetal circulatory system work.
These arteries further divide into chorionic arteries in the chorionic villi where exchange of substances takes place. The partial pressure of oxygen po2 in the umbilical vein is. This blood then enters the umbilical arteries and flows into the placenta. Watch how the blood flows through the fetal circulation and compare it to what happens in the babys body. Fetal hemoglobin, the protein that binds oxygen in the blood, has a higher affinity for oxygen than does maternal hemoglobin. After exchange, oxygenated blood moves from placenta to the fetal circulation through umbilical vein 80% o2. Circulation of blood systemic and pulmonary circulation blood circulationrefers to the flow of blood through all the vessels, which are arranged in a complete circuit or circular pattern systemic circulation carries blood throughout the body path goes from left ventricle through aorta. It is usually established in the fetal period of development and is designed to serve prenatal nutritional needs, as well as permit the switch to a neonatal circulatory pattern at birth. In the placenta the blood becomes enriched with nutrients and oxygen and gets via the unpaired umbilical vein into the fetal blood circulation system. Since the fetus doesnt breathe air, his or her blood circulates differently than it does after birth. During pregnancy, the unborn baby fetus depends on its mother for. The oxygen rich blood that enters the fetus passes through the fetal liver and enters the right side of the heart. Development of the cardiovascular system teachmeanatomy. Fetal blood goes into the placenta through umbilical arteries 58% o2 saturation.
Newborn adaptation to extrauterine life and newborn. The term usually encompasses the entire fetoplacental circulation, which includes the umbilical cord and the blood vessels within the placenta that carry fetal blood. Blood circulation in the fetus and newborn health encyclopedia. Deoxygenated blood passes to the placenta via the umbilical arteries, which arise from the right and left internal iliac arteries. Fetal circulation is the circulation of blood through the cardiovascular system in the human fetus. In the fetus, deoxygenated blood arrives at the placenta via the umbilical arteries and is returned to the fetus in the umbilical vein. The fetal placental circulation allows the umbilical arteries to carry deoxygenated and nutrientdepleted fetal blood from the fetus to the villous core fetal vessels. In this study we observed that third trimester fetal blood flow redistribution with a preferential fetal blood flow to the brain cerebral circulation at the expense of lower body parts, is associated with increased risks of adverse birth outcomes and growth restriction from fetal life onwards. This is because the mother the placenta is doing the work that the babys lungs will do after birth.
In prenatal circulation, the oxygenated blood comes from umbilical vein. Fetal circulation right before birth video khan academy. The oxygen rich blood then returns to the fetus via the third vessel in the umbilical cord umbilical vein. In the placenta, carbon dioxide and waste products are released into the mothers circulatory system. The placenta must therefore receive deoxygenated blood from the fetal systemic organs and return its oxygen rich venous drainage to the fetal systemic arterial circulation. The physiologic rule that all arterial blood flows away from the heart, and all venous blood flows to the heart gets a little backwards in this case. Notes on differences between adult and fetal circulation. All structures unique to fetal circulation are no longer necessary and undergo changes to reflect this. Physiology of the fetal circulation seminars in fetal and neonatal. Fetal circulation, unlike postnatal circulation, involves the umbilical cord and placental blood vessels which carry fetal blood between the fetus and the placenta. Accumulating data on the human fetal circulation shows the similarity to the experimental animal physiology, but with important differences.
Fetal circulation is significantly different from that of a newborn fig. Fetal circulation embryogenesis and development mcat. Modern techniques, particularly ultrasound with its. After the exchange of oxygen and nutrients, the umbilical vein carries fresh oxygenated and nutrientrich blood circulating back to the fetal systemic circulation. Reference ranges of blood flow in the major vessels of the normal human fetal circulation at term by phasecontrast magnetic resonance imaging. These shunts close after birth, and most of the fetal vessels are visible as remnants in the adult circulation. The placenta provides three vessels to the fetus that make up the umbilical cord. More info due to the higher pressure of the blood in the inferior vena cava, more blood flows from it directly into the left atrium via the foramen ovale. Thus, the fetal circulation can be defined as a shuntdependent circulation. Therefore, a computational model of the fetal circulation was developed, including the key elements related to fetal blood redistribution and using measured cardiac outflow profiles to allow.
Fetal circulation how does the fetal circulatory system work. Influence of fetal blood flow redistribution on fetal and. This relatively oxygen rich blood passes predominantly to the head and upper extremities. Successful shift from placental to pul monary respiration. The majority of the blood enters the ductus venosus, a shunt which bypasses the liver and puts blood into the hepatic veins. The function of these shunts is to direct oxygenrich venous blood to the systemic circulation and to ensure oxygendeplete venous blood bypasses the underdeveloped pulmonary circulation. Thus, there is anatomy of fetal circulation harold ellis harold ellis was professor of surgery at westminster medical school, uk, until 1989. Rishi is a pediatric infectious disease physician and works at khan academy. Difference of fetal circulation from an adult ciruclation the fetus has a connection with the maternal blood supply at the site of placenta. During pregnancy, the unborn baby fetus depends on its mother for nourishment and oxygen. The cardiovascular system is one of the first body systems to appear within the embryo.
Some blood from the umbilical vein enters the portal circulation allowing the liver to process nutrients. Deoxygenated blood from the superior vena cava flows into the right atrium, right ventricle, and then into the pulmonary artery. Development of blood vessels and fetal circulation. The first, called the foramen ovale, is a oneway valve that connects the right atrium to the left atrium. Normal fetal circulation and cardiovascular adaptations at birth. In addition, the fetal cardiovascular system is designed in such a way that the most highly oxygenated blood is delivered to the myocardium and brain. Newborn adaptation to extrauterine life and newborn assessment selflearning module. Blood flowing through the foramen ovale and into left atrium passes into the left ventricle where it is ejected into the ascending aorta. At birth, the circulation of the fetal blood through the placenta ceases, acute changes in the pulmonary and systemic vascular resistance occur and the lungs begin to function. This connection is formed by the two umbilical arteries and a single umbilical vein. The human fetus seems to circulate less blood through the placenta, shunt less through the ductus venosus and foramen ovale, but direct more blood through the lungs than the fetal sheep.
Placental blood circulation vascular biology of the. When the embryo develops into the fetus, it creates a functional cardiovascular system that cooperates with the mothers system. Circulation of blood through the fetal heart and lungs and. Fetal circulation is a bit complex and difficult to understand. After exchange, oxygenated blood moves from placenta to the fetal circulation through umbilical vein 80% o2 saturation. Poorly oxygenated and nutrientpoor fetal blood is sent back to the placenta via right and left umbilical arteries. During pregnancy, the fetal lungs are not used for breathing the placenta does the work of exchanging oxygen and carbon dioxide through the mothers. Physiology of the fetal circulation pdf free download. Subsequently the foramen ovale, ductus arteriosus and umbilical vessels close or transform into the corresponding ligaments. Fetus circulation an overview sciencedirect topics. In this article, we shall consider the embryonic development of the heart and cardiovascular system, as well as some important clinical conditions associated with failure of this. Jun 29, 2016 fetal circulation is a bit complex and difficult to understand.
Learn about the anatomy and physiology of fetal and postnatal circulation. Fetal circulation definition of fetal circulation by. Consequently the liver and the lungs are nonfunctional, and a series of shunts exist in. The oxygenated blood is carried from the placenta to the fetus via the umbilical vein. Fetal circulation childrens hospital of philadelphia. Emerging from the placenta is the umbilical vein, which carries oxygenrich blood from the mother to the fetal inferior vena cava via the ductus venosus to the heart that pumps it into fetal circulation. Fetal circulation and babys first breath pediatric nursing neonatal nursing nicu cardiac sonography nursing mnemonics respiratory therapy visual aids nclex annals of medical school discusses how the circulation is different before birth so that blood from the mother can. The function of the umbilical vein is carrying oxygenated and nutrientrich blood from maternal circulation to the fetal circulation, and the umbilical arteries are responsible for transportation.
Successful transition and closure of fetal shunts creates a neonatal circulation where deoxygenated blood returns to the heart through the inferior and superior vena cava. In animals that give live birth, the fetal circulation is the circulatory system of a fetus. This is the organ that develops and implants in the mothers uterus during pregnancy. In the fetus, deoxygenated blood arrives at the placenta via the umbilical arteries. Some blood in the right atrium enters the right ventricle. The foetal and maternal blood never mix, instead they interface at the placenta. Its well known that the blood circulation in the humans varies. The interactions between the postnatal development of the circulation and the presence of congenital cardiovascular malformations have been recognised for many years. Once the main arteries and veins as well as the heart are developed, usually after the 8th week of fetal development, deoxygenated blood is returned from the fetal systemic circulation to the placenta via two umbilical arteries, which branch off the fetal internal iliac arteries. Physiology of fetal circulation university of illinois.
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