Placenta

Definition

The placenta is an essential organ that develops during pregnancy, connecting the developing fetus to the uterine wall. It plays a crucial role in providing oxygen and nutrients to the fetus while also removing waste products from the fetal blood. The placenta facilitates the exchange of substances between the mother and the fetus, ensuring proper growth and development throughout pregnancy.

5 Must Know Facts For Your Next Test

1. The placenta develops from trophoblastic cells that arise from the fertilized egg and is fully formed by about 10 to 12 weeks into pregnancy.
2. It functions as an endocrine organ, producing hormones such as human chorionic gonadotropin (hCG) and progesterone that help maintain pregnancy.
3. The placenta serves as a barrier, protecting the fetus from certain pathogens while allowing maternal antibodies to pass through for immune protection.
4. Maternal blood does not mix with fetal blood; instead, they are separated by a thin layer of tissue that allows for efficient nutrient exchange.
5. The placenta is expelled from the body after childbirth during a process known as the third stage of labor.

Review Questions

• How does the structure of the placenta facilitate its function in supporting fetal development?
  • The structure of the placenta includes a large surface area created by villi, which are tiny finger-like projections that increase contact with maternal blood. This design allows for efficient exchange of oxygen, nutrients, and waste products between maternal and fetal circulations without direct mixing of their blood. Additionally, the thin barrier formed by trophoblasts ensures that essential substances can be transported while protecting the fetus from harmful substances.
• Discuss the hormonal roles of the placenta during pregnancy and their impact on both mother and fetus.
  • The placenta plays a critical endocrine role by producing hormones such as human chorionic gonadotropin (hCG), progesterone, and estrogen. hCG signals the ovaries to maintain hormone production early in pregnancy, preventing menstruation. Progesterone helps maintain the uterine lining and reduces uterine contractions, while estrogen contributes to uterine growth and prepares breast tissue for lactation. These hormones together support fetal development and prepare the mother's body for childbirth.
• Evaluate how abnormalities in placental development can affect pregnancy outcomes and fetal health.
  • Abnormalities in placental development, such as placental insufficiency or previa, can significantly impact pregnancy outcomes. Placental insufficiency may lead to inadequate nutrient supply, resulting in fetal growth restriction or low birth weight. On the other hand, placental previa occurs when the placenta covers part or all of the cervix, potentially causing complications during delivery. These conditions can affect both maternal health and fetal well-being, highlighting the importance of monitoring placental function throughout pregnancy.

Related terms

Chorion: The outermost fetal membrane that forms part of the placenta and contributes to the formation of the umbilical cord.

Amniotic Fluid: The fluid surrounding the fetus within the amniotic sac, providing cushioning and a stable environment for fetal development.

Umbilical Cord: A cord-like structure that connects the fetus to the placenta, facilitating nutrient and oxygen transfer as well as waste removal.