What are the differences between a fetus heart and an adult heart?

The fetal and adult cardiovascular systems exhibit significant differences, reflecting different sources of respiratory and nutritional support. Most strikingly, the embryonic lungs are collapsed and nonfunctional, and the digestive tract has nothing to digest. The nutritional and respiratory needs of the fetus are provided by the diffusion across the placenta.

Blood flow to the placenta is provided by a pair of umbilical arteries which arise from the internal iliac arteries and enter the umbilical cord. Blood returns from the placenta in the single umbilical vein, bringing oxygen and nutrients to the developing fetus. The umbilical vein drains into the ductus venosus, a vascular connection to an intricate network of veins within the developing liver. The ductus venosus collects blood from the veins of the liver and from the umbilical vein, and empties into the inferior cava. When the placental connection is broken at birth, blood flow ceases along the umbilical vessels, and they soon degenerate. However, remnants of these vessels persist throughout life as fibrous cords.

Throughout embryonic and fetal life, the lungs are collapsed; yet after delivery, the newborn infant must be able to extract oxygen from inspired air rather than across the placenta.

Although the interatrial and interventricular septa develop early in fetal life, the interatrial partition remains functionally incomplete until birth. The foramen ovale, or interatrial opeing, is associated with a long flap that acts as a valve. Blood can flow freely from the right atrium to the left atrium, but any backflow will close the valve and isolate the two chambers from one another. Thus, blood entering the heart at the right atrium can bypass the pulmonary circuit. A second short-circuit exists between the pulmonary and aortic trunks. This connection, the ductus arteriosus, consists of a short, muscular vessel.

With the lungs collapses, the capillaries are compressed and little blood flows through the lungs. During diastole, blood enteres the right atrium and flows into the right ventricle, but it also passes into the left atrium through the foramen ovale. Avout 25 percent of the blood arriving at the risght atrium bypasses the pulmonary circuit in thie way. In addition, more than 90 prcent of the blood leaving the right ventricle passes through the ducus arteriosus and enters the systemic circuit rather than continuing to the lungs.

After birth, when the infant takes the first breath, the lungs expand, and so do the pulmonary vessels. The resistance in the pulmonary circuit declines suddenly, and blood rushes into the pulmonary vessels. Within a few seconds, rising oxygen levels stimulate the constriction of the ductus arteriosus, isolating the pulmonary and aortic trunks from one another. As pressures rise in the left atrium, the valvular flap closes the floramen ovale. In adults, the interatrial septum bears the fossa ovalis, a shalow depression that marks the side of the foramen ovale. The remnants of the ductus arteriousus, persists throughout life as the ligamentum arteriosum, a fibrous cord.

The fetal and adult cardiovascular systems exhibit significant differences, reflecting different sources of respiratory and nutritional support. Most strikingly, the embryonic lungs are collapsed and nonfunctional, and the digestive tract has nothing to digest. The nutritional and respiratory needs of the fetus are provided by the diffusion across the placenta.

Blood flow to the placenta is provided by a pair of umbilical arteries which arise from the internal iliac arteries and enter the umbilical cord. Blood returns from the placenta in the single umbilical vein, bringing oxygen and nutrients to the developing fetus. The umbilical vein drains into the ductus venosus, a vascular connection to an intricate network of veins within the developing liver. The ductus venosus collects blood from the veins of the liver and from the umbilical vein, and empties into the inferior cava. When the placental connection is broken at birth, blood flow ceases along the umbilical vessels, and they soon degenerate. However, remnants of these vessels persist throughout life as fibrous cords.

Throughout embryonic and fetal life, the lungs are collapsed; yet after delivery, the newborn infant must be able to extract oxygen from inspired air rather than across the placenta.

Although the interatrial and interventricular septa develop early in fetal life, the interatrial partition remains functionally incomplete until birth. The foramen ovale, or interatrial opeing, is associated with a long flap that acts as a valve. Blood can flow freely from the right atrium to the left atrium, but any backflow will close the valve and isolate the two chambers from one another. Thus, blood entering the heart at the right atrium can bypass the pulmonary circuit. A second short-circuit exists between the pulmonary and aortic trunks. This connection, the ductus arteriosus, consists of a short, muscular vessel.

With the lungs collapses, the capillaries are compressed and little blood flows through the lungs. During diastole, blood enteres the right atrium and flows into the right ventricle, but it also passes into the left atrium through the foramen ovale. Avout 25 percent of the blood arriving at the risght atrium bypasses the pulmonary circuit in thie way. In addition, more than 90 prcent of the blood leaving the right ventricle passes through the ducus arteriosus and enters the systemic circuit rather than continuing to the lungs.

After birth, when the infant takes the first breath, the lungs expand, and so do the pulmonary vessels. The resistance in the pulmonary circuit declines suddenly, and blood rushes into the pulmonary vessels. Within a few seconds, rising oxygen levels stimulate the constriction of the ductus arteriosus, isolating the pulmonary and aortic trunks from one another. As pressures rise in the left atrium, the valvular flap closes the floramen ovale. In adults, the interatrial septum bears the fossa ovalis, a shalow depression that marks the side of the foramen ovale. The remnants of the ductus arteriousus, persists throughout life as the ligamentum arteriosum, a fibrous cord.