What happens to the ductus venosus when the baby takes its first breath?

What happens to the ductus venosus when the baby takes its first breath?

• A. Becomes the ligamentum teres
• B. Remains open
• C. Becomes the ligamentum arteriosum
• D. It closes becoming the ligamentum venosum

Answer: (D)

When a baby takes its first breath, fetal circulation undergoes a dramatic change. The ductus venosus, which shunts a portion of oxygen-rich blood from the umbilical vein directly to the inferior vena cava, closes as placental circulation ceases and blood flow through the umbilical vein drops. The resulting fall in flow, along with the birth-era rise in oxygen and changes in pressures, causes the smooth muscle in the ductus venosus to constrict. This functional closure happens within minutes, and over weeks the ductus venosus becomes fibrous tissue, leaving a permanent remnant called the ligamentum venosum in the liver. By contrast, the ligamentum venosum is not formed from the umbilical vein or the ductus arteriosus—those remnants are the ligamentum teres and the ligamentum arteriosum, respectively.

When a baby takes its first breath, fetal circulation undergoes a dramatic change. The ductus venosus, which shunts a portion of oxygen-rich blood from the umbilical vein directly to the inferior vena cava, closes as placental circulation ceases and blood flow through the umbilical vein drops. The resulting fall in flow, along with the birth-era rise in oxygen and changes in pressures, causes the smooth muscle in the ductus venosus to constrict. This functional closure happens within minutes, and over weeks the ductus venosus becomes fibrous tissue, leaving a permanent remnant called the ligamentum venosum in the liver. By contrast, the ligamentum venosum is not formed from the umbilical vein or the ductus arteriosus—those remnants are the ligamentum teres and the ligamentum arteriosum, respectively.