Question

Name the 5 fetal structures and the main pathway of blood flow in fetal circulation. In your answer include the following: location of the fetal structures, functions of the fetal structures, and what postnatal structure each fetal structure becomes in the newborn circulation

Answer 1

The 5 fetal structures are as following :

1. Foramen Ovale
2. Umbilical Vein
3. Ductus Venosus
4. Umbilical Arteries & abdominal ligaments
5. Ductus Arteriosum

Main pathway of blood flow in fetal circulation :

The umbilical vein carries blood from the placenta to the fetus. Even though, this is called a vein, it actually carries oxygen - rich blood. Some of the blood passes through an opening called the fetus ductus venosus and enters the inferior venacava. The inferior venacaca is a vessel that takes blood to the fetal heart. The rest of the blood enters the fetal liver through the vessel called the portal vein. The blood then moves to the right atrium of the heart.

In the fetus, there is an opening between the right and left atrium called the foramen ovale. Most of the blood flows through the hole directly into the left atrium from the right atrium. Fetal blood does not travel through the lungs because of this hole between the atria. The fetal blood travels from the left atrium to the left ventricle. Then it is pumped through the aorta, or the largest artery, into the body. Once the blood has lost much of its oxygen & picked up waste from the fetus, it returns to the placenta. The umbilical arteries are responsible for taking oxygen-poor blood and waste back to the placenta.

Location of fetal structures :

1. Foramen ovale - It is small hole located in the septum, which is the wall between the two upper chambers of the heart.
2. Umbilical vein - It is a vein present during fetal development that carries oxygenated blood from the placenta into the growing fetus.
3. Ductus Venosus - It shunts a portion of the left umbilical vein blood flow directly to the inferior venacava. Thus, it allows oxygenated blood from the placenta to bypass the liver.
4. Umbilical arteries - It is a paired artery that is found in the abdomen and pelvic regions, it extends to the umbilical cord.
5. Ductus arteriosum - It is a blood vessel connecting the main pulmonary artery to the proximal descending aorta.

Function of fetal structures :

1. Foramen Ovale : The shunts that bypass the lungs. These shunts move blood from the right atrium of the heart to the left atrium.
2. Umbilical vein - It is a vein present during fetal development that carries oxygenated blood from placenta into the growing fetus.
3. Ductus Venosus - It shunts a portion of the left umbilical vein blood flow directly into the inferior venacava.Thus, it allows oxygenated blood from the placenta to bypass the liver.
4. Umbilical Artery - It carries deoxygenated, nutrient depleted blood from the fetus to the placenta.
5. Ductus Arteiosum - It allows most of the blood from the right ventricle to bypass the fetus's fluid-filled non-functioning lungs.

Fetus structure becomes in new born circulation :

1. Foramen Ovale - Fossa Ovalis
2. Umbilical vein - Ligamentum teres
3. Ductus Venosus - Ligamentum venosum
4. Umbilical arteries & abdominal ligaments - Medial umbilical ligaments, Superior vesicular artery
5. Ductus Arteriosum - Ligamentum arteriosum