Meet the placenta! | Reproductive system physiology | NCLEX-RN | Khan Academy

Summary

This video explores the remarkable partnership between a mother and her developing fetus, highlighting how the placenta and umbilical cord meet the fetus's needs. It explains how the fetus receives oxygen and nutrients and eliminates waste while floating in amniotic fluid. The transcript details the anatomy of the umbilical cord, including one vein and two arteries encased in Wharton's jelly, and illustrates how fetal trophoblast cells interact with maternal blood in the placenta. Using clear analogies, it conveys how maternal and fetal tissues cooperate for gas and nutrient exchange, emphasizing the placenta as the first vital organ enabling mother and baby to work together for survival and growth.

Takeaways

• 👶 The fetus develops inside the uterus, a strong muscular organ in women.
• 💧 The baby floats in amniotic fluid for nine months, which affects breathing and waste management.
• 🫁 The lungs of the fetus are filled with fluid, so oxygen and carbon dioxide exchange occurs differently than after birth.
• 🍬 Nutrients like glucose are provided to the fetus without direct eating, via maternal blood supply.
• 🩺 The placenta is the organ that enables exchange of oxygen, nutrients, and waste between mother and baby.
• 🔴 The umbilical vein carries oxygen-rich blood from the placenta to the fetus, while the umbilical arteries carry oxygen-poor blood away from the fetus.
• 🟦 The umbilical vessels are protected and supported by Wharton's jelly.
• 🖐️ The placenta has a maternal side (basal plate) and a fetal side (chorionic plate), with shared exchange space in between.
• 🌊 Maternal blood pools in the placenta, allowing diffusion of oxygen and nutrients into fetal blood without direct mixing of blood cells.
• 🌱 Trophoblast cells from the fetus invade maternal tissue to facilitate nutrient and gas exchange.
• 🤝 The placenta represents the first cooperative interaction between mother and baby for survival and growth.
• 🔄 The structure of the placenta, including branching vessels and finger-like projections, maximizes surface area for efficient exchange.

Q & A

What is the uterus and what role does it play during pregnancy?

The uterus is a strong, muscular organ in women where the fetus develops. It provides a protective environment and helps during childbirth by contracting to push the baby out.

What is amniotic fluid and why is it important for the fetus?

Amniotic fluid surrounds the fetus in the uterus, allowing it to 'swim' safely. It cushions the fetus, maintains temperature, and provides a medium in which the fetus can move and develop.

How does the fetus receive oxygen if its lungs are filled with amniotic fluid?

The fetus receives oxygen through the placenta, not the lungs. Oxygen from the mother's blood diffuses into the fetal blood via the umbilical vein in the umbilical cord.

How does the fetus obtain nutrients such as glucose?

Nutrients like glucose pass from the mother's blood into the fetus' blood through the placenta, ensuring the fetus has the energy needed for growth and development.

How does the fetus eliminate waste products like carbon dioxide?

Waste products, including carbon dioxide, diffuse from the fetus' blood into the mother's blood through the placenta, where the mother’s body can process and remove them.

What is the placenta and why is it essential during pregnancy?

The placenta is an organ that facilitates nutrient and gas exchange between mother and fetus. It allows oxygen and nutrients to reach the fetus and waste products to be removed, serving as the first collaboration between mother and baby.

What is the structure of the umbilical cord?

The umbilical cord contains one umbilical vein (carrying oxygenated blood to the fetus) and two umbilical arteries (carrying deoxygenated blood away from the fetus), all encased in Wharton’s jelly for protection.

What are trophoblast cells and what is their function?

Trophoblast cells are specialized fetal cells that invade maternal tissue to establish close contact with maternal blood. They enable the exchange of oxygen, nutrients, and waste between mother and fetus.

What is the difference between the basal plate and the chorionic plate in the placenta?

The basal plate is the maternal portion of the placenta containing uterine arteries and veins, while the chorionic plate is the fetal portion containing fetal vessels. The placenta facilitates exchange between these two areas.

How does blood circulation in the placenta differ from typical blood circulation in the body?

In the placenta, maternal blood from uterine arteries pools in open spaces rather than flowing entirely through vessels, allowing diffusion of oxygen and nutrients into fetal capillaries, unlike typical closed blood vessel circulation.

Why are the umbilical arteries drawn in blue and the vein in red, even though veins normally carry deoxygenated blood?

In the umbilical cord, the vein carries oxygenated blood from the placenta to the fetus, so it is drawn red, while the arteries carry deoxygenated blood from the fetus to the placenta, so they are drawn blue, which is opposite of usual conventions.

How does the placenta demonstrate collaboration between mother and fetus?

The placenta is the first system in which the mother and fetus work together: maternal blood supplies oxygen and nutrients, fetal blood collects them and removes waste, creating a shared environment that supports fetal growth.