Fetal Circulation (Before and After Birth) Maternity Nursing Heart Shunts NCLEX

Summary

This video explains fetal circulation and how it differs from normal circulation after birth. The instructor reviews the typical blood flow through the heart and highlights the key difference in fetal circulation, which involves three shunts that bypass the lungs. The fetus relies on the placenta for oxygen and nutrients, delivered through the umbilical cord. The video also covers how the circulation system changes after birth when the baby begins using its lungs, leading to the closure of these shunts. Viewers are invited to take a quiz to test their knowledge on the topic.

Takeaways

• 🌟 Fetal circulation is different from adult circulation because the fetus does not use its lungs for oxygenation.
• 🔄 The fetus relies on the placenta to exchange oxygen and nutrients, bypassing the need for lung function.
• 🚫 Three main shunts in fetal circulation are the ductus venosus, foramen ovale, and ductus arteriosus, which allow blood to bypass the lungs.
• 📍 The ductus venosus shunts blood from the umbilical vein to the inferior vena cava.
• 🔄 The foramen ovale allows oxygenated blood to flow from the right atrium to the left atrium.
• 🔗 The ductus arteriosus connects the pulmonary artery to the aorta, directing blood away from the non-functional lungs.
• 💧 The placenta acts as a temporary lung, providing oxygen and nutrients to the fetus and removing waste.
• 🌀 Blood flow in the fetus is directed to ensure the most oxygenated blood reaches the brain and other vital organs.
• 👶 After birth, the baby's first breaths cause the lungs to expand, changing blood pressure and closing the fetal shunts.
• 🛑 The closure of the foramen ovale and ductus arteriosus is crucial for the transition to independent respiration and circulation.
• ❗ Failure to close these shunts after birth can lead to congenital heart defects.

Q & A

What is the main difference between fetal circulation and normal postnatal circulation?

The main difference is that fetal circulation involves shunts to bypass the lungs, which are non-functional in utero, while postnatal circulation relies on the lungs for oxygen exchange.

Why does the fetal circulatory system bypass the lungs?

The fetal circulatory system bypasses the lungs because the fetus is not breathing air; its lungs are filled with fluid. Oxygen is provided by the placenta, so the blood is shunted away from the lungs.

What are the three main shunts in fetal circulation, and what are their roles?

The three main shunts are the ductus venosus, foramen ovale, and ductus arteriosus. The ductus venosus bypasses the liver, the foramen ovale allows blood to flow between the right and left atrium, and the ductus arteriosus connects the pulmonary artery to the aorta, bypassing the lungs.

What is the function of the placenta in fetal circulation?

The placenta functions as the site for gas exchange and nutrient delivery in fetal circulation, providing oxygen and nutrients from the mother’s blood and removing waste products from the fetus.

How does the umbilical cord contribute to fetal circulation?

The umbilical cord has one umbilical vein, which carries oxygenated blood from the placenta to the fetus, and two umbilical arteries, which carry deoxygenated blood back to the placenta for waste removal and reoxygenation.

What happens to the shunts after birth?

After birth, the shunts (ductus venosus, foramen ovale, and ductus arteriosus) close due to changes in pressure and the baby's need to use its lungs for oxygen exchange. The closure ensures blood flows properly to the lungs for oxygenation.

Why does the foramen ovale close after birth?

The foramen ovale closes after birth because the pressure in the left atrium becomes higher than the right atrium, reversing the flow of blood and eliminating the need for this shunt.

What role do prostaglandins play in fetal circulation?

Prostaglandins, produced by the placenta, help keep the ductus arteriosus open during fetal development. After birth, the removal of the placenta and the decrease in prostaglandins allow the ductus arteriosus to close.

What happens if the foramen ovale does not close after birth?

If the foramen ovale does not close after birth, it results in a condition called a patent foramen ovale (PFO), which can lead to abnormal circulation where blood may still bypass the lungs.

How does the resistance in the fetal lungs affect blood flow?

In the fetus, the lungs are filled with fluid, causing high resistance. This high resistance directs blood away from the lungs through the ductus arteriosus and the foramen ovale, ensuring that blood bypasses the non-functional lungs.