Topic 3 Circulatory System: Fetal Circulation

Question 1

• Process that occurs both inside of the mother and her fetus that essentially temporarily re-wires the cardiovascular systems

Answer 1

Fetal Circulation

Question 2

• Oxygenated, nutrient-rich blood from placenta carried to fetus via umbilical vein → half of the blood enters the ductus venosus, which allows blood to bypass the liver → blood is carried to the inferior vena cava → right atrium → right ventricle → ductus arteriosus (conducts some blood from the pulmonary artery to the aorta [bypassing the lungs/fetal pulmonary circulation]) → aorta
• The other half of the blood that didn’t enter the ductus venosus enters the liver/portal vein → right atrium → foramen ovale (a small opening in the heart which allows blood to bypass pulmonary circulation by entering the left atrium directly from the right atrium since there is no gas exchange in the fetal lung) → left atrium → left ventricle → aorta

Answer 2

Process as follows

Question 3

• CO2 stimulates baby’s first breath as receptors in nose detect it and acts as a respiratory stimulant
• Temp change from leaving womb stimulates first breath
• Surfactant is epically important here because the first breath is difficult – newborn lungs are collapsed and airways are small, leading to lots of resistance to air movement

Answer 3

Note