Pulmonary Arteries and Umbilical Vessels: Unique Circulatory Roles

Pulmonary Arteries

• Carry deoxygenated blood from right ventricle → lungs for oxygenation.
• Only arteries carrying deoxygenated blood in adult circulation.
• Low pressure, high compliance.

Umbilical Vessels (Fetal Circulation)

• Two umbilical arteries: Carry deoxygenated blood + waste from fetus → placenta.
• One umbilical vein: Carries oxygenated, nutrient-rich blood from placenta → fetus.

At birth, cord clamping triggers transition: pulmonary circulation expands, umbilical vessels obliterate (ligamentum teres, medial umbilical ligaments).

These specialized vessels exemplify structure–function adaptation in circulatory physiology.