494 Review Sheet 32 Fetal Circulation 15. For each of the following indicate its

ID: 3510104 • Letter: 4

Question

494 Review Sheet 32 Fetal Circulation 15. For each of the following indicate its or what it is ng structures, first indicate its function in the fetus; and then note its fate (what happens ted to after birth). Circle the blood vessel that carries the most oxygen-rich blood. Structure to it Function in fetus Umbilical artery Fate and postnatal structure Umbilical vein Ductus venosus Ductus arteriosus Foramen ovale What organ serves as a respiratory/digestive/excretory organ for the fetus? atic Portal Circulation hat is the source of blood in the hepatic portal system?

Explanation / Answer

Structure

Function in Fetus

Fate and postnatal structure

Umblical Artery

Umbilical artery carries nutrient deprived deoxygenated blood that contains waster products from the fetus to the placenta. Two umbilical arteries in the umbilical cord surround the urinary bladder. It passes to the right side of the liver. In the liver, it is joined by the portal vein. The blood drains in to the inferior vena capa through hepatic veins.

The open proximal portions represent a branch of the anterior (front) part of the interior iliac arteries. The intra abdominal portion forms the medial ligament. The umbilical artery in the pelvis forms the superior vesicle arteries in the bladder. It also forms the deferential artery that supplies blood to ducts deferens in the males.

Umblical vein

Umbilical vein carries oxygenated blood that is rich in nutrients from the placenta to the fetus. The vein carries oxygen and nutrient rich blood derived from maternal-fetal exchange at the chorionic villi. Most of the blood enters the liver from its inferior border. The remaining blood is shunted to the inferior vena cava through the ductus venosus.

The right umbilical vein and the proximal left vein degenerates. The umbilical veins (extra hepatic portion) become remnants of the ligamentum teres hepatis. Umbilical vein forms the ligament arteriosum that passes from the umbilicus to the porta hepatis. In the porta hepatis, it attaches to the left branch of the portal vein.

Ductus venosus

Ductus venosus is a single channel from the vitelline that connects the umbilical vein and inferior vena capa (IVC). It allows bypass of liver capillaries. The ductus The ductus venous has a diameter that is one-third of the umbilical vein. Hence, blood is shunted to the IVC under pressure, which propels the blood from the IVC to the right atrium. From the right artium, it flows directly into the left atrium via the foramen ovale. The blood enters the left ventricle and aorta to enter the systemic circulation.

The ductus venosus closes after birth and remains as ligamentum venosum. Ligamentum venosum passes through the liver from the left branch of the portal vein. It enters the inferior vena cava.

Ductus arteriosus

The ductus arteriosum is a shunt that allows flow of less oxygenated blood from pulmonary artery to the aorta. The blood enters the umbilical arteries and then the placenta.

It protects lungs against circulatory overload. It strengthens the right ventricle. It carries mostly medium oxygen saturated blood.

The ductus arteriosus becomes the ligamentum arteriosum after birth. The ligamentum arteriosum passes from the left pulmonary artery to the aortic arch. This aortic arch closes by the third postnatal month and is absent in the adult.

Foramen ovale

The foramen ovale is an interatrial communication and shunts highly oxygenated blood from the right to left atrium. It allows blood from the inferior vena cava to enter the left atrium. Hence, blood can flow from the veins to the right side of the fetal heart. It can directly enter to the left side of the heart. It is located in the septum between the two chambers of the heart as a small hole.

The foramen ovale closes after birth. The foramen ovale is closed because the left side of the heart has increased pressure after birth. The foramen ovale is closes and the blood flows to the lungs to obtain oxygen. It then enters the left side of the heart to be transported to the entire body.

It is the umblical vein that carries mosr oxygen rich blood. Kindlt circle it when you submit the answer. I cannot circle it here, as it not allowing me to do so. Thanks.