xplain the role of placenta in the development of human embryo

The placenta feeds the growing baby, removes wastes, exchanges gases, produces vital hormones, and protects the fetus by acting as a selective barrier between mother and baby.

What the placenta is?

The placenta is a temporary organ that forms after implantation. It connects the fetus to the mother’s uterus through the umbilical cord. On the baby’s side it has finger-like chorionic villi, and on the mother’s side it attaches to the uterine lining (decidua basalis). Maternal blood flows around the villi in special spaces, allowing exchange without the two blood supplies directly mixing.

Main functions of the placenta

• Nutrition: Transfers glucose, amino acids, fatty acids, vitamins, minerals, and water from the mother to the fetus. Active transport and carrier proteins help move key nutrients even against gradients.
• Gas exchange: Oxygen passes from mother to baby; carbon dioxide moves from baby to mother. Thin membranes and large surface area make this efficient.
• Waste removal: Urea, uric acid, bilirubin (from the fetus) cross to the mother for excretion by her kidneys and liver.
• Hormone production (endocrine role): Produces hCG (supports early pregnancy and corpus luteum), progesterone (maintains uterine lining, relaxes uterus), estrogens (uterine growth, blood flow), and hPL / placental lactogen (alters maternal metabolism to supply glucose to the fetus).
• Immune protection: Acts as a partial barrier; transfers protective IgG antibodies from mother to fetus, giving passive immunity to the newborn for the first months.
• Detoxification and barrier function: Limits passage of many pathogens and harmful chemicals, though not all (e.g., some viruses, alcohol, and certain drugs can cross).
• Fluid and temperature balance: Helps regulate fetal fluid status and contributes to amniotic fluid equilibrium, supporting a steady temperature and cushioned environment.
• Anchoring & birth: Firmly secures the fetus to the uterus during pregnancy; after delivery, the placenta separates and is expelled as the afterbirth.

Umbilical cord basics

The umbilical cord usually contains two arteries and one vein. The vein brings oxygen- and nutrient-rich blood from the placenta to the fetus; the arteries carry deoxygenated, waste-laden blood from the fetus back to the placenta. A jelly-like tissue called Wharton’s jelly protects these vessels.

Why the placenta is vital?

• Growth support: Continuous, tailored nutrient delivery fuels rapid fetal growth.
• Homeostasis: Keeps the fetal environment stable despite daily changes in the mother.
• Adaptation: Placental hormones shift the mother’s metabolism to favor fetal needs.