Art-labeling Activity: Fetal Circulation Drag the labels onto the diagram to identify the blood vessels and components of the fetal circulation. Ductus arteriosus (open) Foramen ovale (open) Aorta Placenta Ductus venosus Pulmonary trunk Umbilical cord Inferior vena cava Umbilical arteries Umbilical vein Liver Reset Help 14 of 15
The Correct Answer and Explanation is:
Here are the correct labels for the diagram of fetal circulation.
Top to bottom on the left side:
- Placenta
- Umbilical cord
- Umbilical vein
Top to bottom on the right side:
- Ductus arteriosus (open)
- Aorta
- Pulmonary trunk
- Foramen ovale (open)
- Ductus venosus
- Inferior vena cava
- Umbilical arteries
Explanation of Fetal Circulation
Fetal circulation is a unique system that allows the developing fetus to receive oxygen and nutrients from the mother while bypassing its own non-functional lungs and liver. The process begins at the placenta, the vital organ where gas, nutrient, and waste exchange occurs between maternal and fetal blood.
Oxygenated blood leaves the placenta and travels to the fetus through the umbilical vein, located within the umbilical cord. Upon entering the fetus, about half of this blood flows through the fetal liver. The other half is shunted away from the liver through a special vessel called the ductus venosus. This shunt allows highly oxygenated blood to flow directly into the inferior vena cava, where it mixes with deoxygenated blood returning from the lower body of the fetus.
This mixed blood enters the right atrium of the heart. Because fetal lungs are not functional, the circulatory system has two shunts to divert blood away from the pulmonary circuit. The first is the foramen ovale, an opening between the right and left atria. Most of the blood entering the right atrium flows directly through this opening into the left atrium, bypassing the right ventricle and lungs. From the left atrium, the blood moves to the left ventricle and is pumped into the aorta to supply the brain and upper body with more highly oxygenated blood.
The remaining blood in the right atrium enters the right ventricle and is pumped into the pulmonary trunk. The second shunt, the ductus arteriosus, connects the pulmonary trunk directly to the aorta. This allows the majority of the blood from the right ventricle to bypass the lungs and enter the systemic circulation. Finally, deoxygenated blood returns to the placenta for reoxygenation. It travels through the umbilical arteries, which branch from the internal iliac arteries and exit the fetus through the umbilical cord.
