Embryology: placenta and umbilical cord
Human Anatomy · MBBS
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Study notes
A newborn's cord is clamped — why doesn't the baby bleed out? The umbilical cord has two arteries carrying waste blood from baby to placenta and one vein bringing oxygenated, nutrient-rich blood back. At birth, clamping stops this circuit; the newborn's own lungs and gut take over. The cord stump dries and falls off in 1–2 weeks, leaving the umbilicus (belly button). Notably the vein carries oxygen-rich blood — the reverse of adult veins — because 'toward the heart' here means toward the baby's heart from the placenta.