Placenta (P)

Placenta (P)

Definition: The placenta (P) is a temporary organ that develops in the uterus during pregnancy. It serves as the interface between the mother and the developing fetus, facilitating nutrient and gas exchange while also providing immunological protection.

Structure of the Placenta

• Maternal Side: Composed of decidual tissue from the mother, which forms a rich vascular network to supply blood to the placenta.
• Fetal Side: Contains chorionic villi, which are finger-like projections that increase surface area for nutrient absorption and gas exchange.

Functions of the Placenta

• Nutrient Transfer:

• The placenta transports essential nutrients (e.g., glucose, amino acids, fatty acids) from the maternal blood to the fetus.

• Gas Exchange:

• Oxygen from maternal blood is delivered to the fetus, while carbon dioxide produced by fetal metabolism is transferred back to the mother for exhalation.

• Hormone Production:

• The placenta produces several hormones crucial for maintaining pregnancy, including:
  • Human Chorionic Gonadotropin (hCG): Supports corpus luteum function and prevents menstruation.
  • Progesterone: Maintains the uterine lining and prevents contractions.
  • Estrogens: Promote uterine growth and blood flow.

• Immunological Protection:

• The placenta acts as a barrier to protect the fetus from maternal immune responses while allowing selective transfer of antibodies (e.g., IgG) for passive immunity.

• Waste Elimination:

• Metabolic waste products from the fetus are transported back to the maternal circulation for elimination.

Clinical Relevance

• Placental Disorders: Conditions such as placenta previa (placenta covering the cervix) and placental abruption (premature separation from the uterine wall) can lead to complications during pregnancy.
• Placental Insufficiency: Inadequate blood flow to the placenta can result in fetal growth restriction and other complications.
• Placenta Accreta: An abnormal attachment of the placenta to the uterine wall can complicate delivery and lead to severe bleeding.

Conclusion

The placenta is a vital organ during pregnancy that supports fetal development through nutrient transfer, gas exchange, hormone production, and immunological protection. Understanding its structure and functions is essential for managing pregnancy-related health issues.

References

1. Moore KL, Persaud TVN. “The Developing Human: Clinically Oriented Embryology.” 10th ed. Elsevier; 2015.
2. Cunningham FG, et al. “Williams Obstetrics.” 25th ed. McGraw-Hill; 2018.
3. Jansen L, et al. “Placental Function in Health and Disease.” Nature Reviews Endocrinology. 2018; 14(11): 670-685. DOI: 10.1038/s41574-018-0060-0