CIRCULATORY SYSTEM: Fetal Circulation

Question 1

Does the fetus use its lungs?

Answer 1

NO

Question 2

Where does the exchange of nutrients between fetus and mother take place? How does it occur?

Answer 2

the placenta

diffusion

Question 3

What is the placenta?

Answer 3

Large disk of tissue
attached to the uterine wall (mom and baby’s blood vessels right next to each other)
allows for nutrient, waste and gas exchange

Question 4

What are the 4 special circulatory features found in the fetus?

Answer 4

Foramen Ovale
Ductus Arteriosus
Umbilical Cord
Ductus Venosus

Question 5

What does the foramen Ovale do?

Answer 5

opening between the left and right atria
allows blood to bypass the lungs
reroutes most of blood from the right atrium to the left atrium

Question 6

What does the Ductus Arteriosus

do?

Answer 6

Small arterial connection
between pulmonary artery and aorta
further allows blood to bypass the lungs

Question 7

What does the Umbilical cord do?

Answer 7

has 3 blood vessels

• large one (umbilical vein) transports blood with oxygen and nutrients to the fetus
• other 2 (umbilical arteries branching off the iliac vein) take waste and CO2 back to mother

Question 8

In the fetus where do veins do? Arteries?

Answer 8

Veins= to the baby

Arteries=Away

Question 9

What does the Ductus Venosus do?

Answer 9

blood vessels connects the umbilical vein to the vena cava
allows oxygenated blood to bypass the liver
joins with vena cava and goes to heart

Question 10

What changes occur at birth?

Answer 10

• First breath=lungs fill with air and O2 levels rise resulting in increase in pulmonary blood flow
• Placenta is removed, foramen ovale, ductus venosus and ductus arteriosus close

Question 11

Explain the pathway of blood through the fetus

Answer 11

• Blood collects in right atrium
• blood goes into left atrium through the oval opening and into right ventricles through AV valves
• Right Ventricle to pulmonary artery (most blood goes through the arterial duct to aorta)
• Aorta to the tissue (umbilical arteries to placenta)
• Umbilical vein carries O2 blood that enters the venus duct and bypases the liver
• venus duct joins with inferior vena cava, mixes with deO2 blood then goes back to heart