Circulation

Question 1

Transferred from Fetal Circulation to mother? (4)

Answer 1

CO2, H2O, Urea (Waste products), Hormones

Question 2

Transferred from maternal circulation to fetus? (7)

Answer 2

02, h20- electrolytes, nutrients, hormones, IgG, Drugs (alcohol), pathogens

Question 3

Describe Fetal Circulation:

Answer 3

1. Oxygenated blood from placenta enters through umbilical veins
2. Most of the blood bypass fetal liver via the ductus venosus and mix with deoxygenated blood in inferior vena cava
3. Foramen ovale shunts blood from right atrium (increase pressure) directly into left atrium (decrease pressure)
4. Blood is shunted away from fetal lungs (increased resistance)
5. Ductus arteriosus connects pulmonary artery directly to aorta
6. Deoxygenated blood returns to placenta via the umbilical arteries

Question 4

Pathway of blood through fetal circulation

Answer 4

Umbilical vein– ductus venosus – inferior vena cava – right atrium – left atrium (through foramen ovale) –left ventricle – aorta –body

Question 5

Umbilical arteries (2)

Answer 5

return deoxygenated blood from fetal internal iliac arteries to placenta.
Umbilical arteries have low O2 sat.

Question 6

Umbilical vein (1)

Answer 6

supplies oxygenated blood from placenta to fetus, drain into IVC via ductus venosus or liver.
80% saturated with O2.

Question 7

Describe ductus venosus :

Answer 7

Blood entering the fetus through umbilical vein is conducted via the ductus venosus into IVC to bypass the liver

Question 8

Describe foramen ovale

Answer 8

Most oxygenated blood reaching the heart via the IVC is diverted through foramen ovale and pumped out the aorta to head and body

Question 9

Describe ductus arteriosus

Answer 9

Deoxygenated blood from the SVC is expelled into the pulmonary artery and ductus arteriosus to the lower body of the fetus

Question 10

What happens at birth to fetal circulation?

Answer 10

At birth infant takes a deep breath; decreased resistance in pulmonary vasculature causes increased left atrial pressure vs. right atrial pressure; formen ovale closes (now called fossa ovalis); increased in O2 leads to decrease in prostaglandins, causing closure of ductus atreriosus.

Question 11

What does indomethacin do to PDA? What does Prostaglandis to to PDA?

Answer 11

• Indomethacin helps close PDA.

- Prostaglandins keep PDA open

Question 12

Fetal blood has:
PaCO2: _____
PaO2= ______

Answer 12

PaCO2 = 48 mmHg
PaO2 =   30 mmHg (+10 increase if mother is on 100% O2)

Question 13

Ductus arteriosus closes in ____weeks and foramen ovale takes _____ to close

Answer 13

2-3,months

Question 14

If a neonate has hypoxia or acidosis in first few day, what do you suspect?

Answer 14

PDA or PFO. Left to right–> pulmonary HTN.