Foetal Circulation

Question 1

Characteristics

Answer 1

• PLACENTA plays role of Lungs+ Digestive system + Kidney

LUNGS: Non-Functioning: Blood bypass lunge by FORAMEN OVALE!

Question 2

Characteristics

LIVER

Answer 2

• Oxygenated blood–> Umbillical Vein(In umbillical chord) -> LIVER
• Collateral branches -> Left liver = UMBILLICAL Morety
• Right branches of V. Portae ->Right liver = Portal Morety
• Non-FUNCTOINING V. HEPATICA –>
• Ductus Venosus
• Bypass the v. Hepatic –> V.Cava caud direct

Question 3

Foramens of the Fetal circularion

Answer 3

Foramen OVALE: Devides BS into L+R Atrium

Question 4

Fetal circularion AFTER BIRTH

Answer 4

1. Umbillical vein
   - Lig. Teres hepatis
   - Lig. Falciforme hepatis
2. Umbillical arteries
   - Lig. Teres Vesicae
3. Ductus Venous closes -> V. Porta perforates LIVER
4. Decrease pressure in RA + increased Pressure in LA
   = FORAMEN OVALE closes
5. Lungs-> Functional –> Ductus Arteriosus closes = Lig. ARTERIOSUS

Question 5

Foetal circulation

Where does Fetuses derive oxygenated blood and nutrients from?

Answer 5

Fetuses derive oxygenated blood and nutrients from the placenta rather than the lungs.
○ Flow to the fetal lungs is low whereas the amount of blood perfuming the
placenta is high
○ Fetal pulmonary vascular resistance and arterial pressure are high

Question 6

Fetal circulation is characterized by?

Answer 6

Fetal circulation is characterized by the presence of several important shunts
○ Foramen ovale: foramen between left and right atrium

○ Ductus arteriosus : vascular conduit between the pulmonary artery and aorta, allows blood to flow from the high-pressure pulmonary artery to the
lower-reassure aorta (only 10-12% of the blood flows through the lungs)

■ These 2 cause the fetal right and left ventricles to operate as parallel
pumps

○ Ductus venosus : low-resistance conduit that allows a significant fraction of
relatively oxygenated blood in the umbilical vein to bypass the fetal liver and
directly enter the caudal vena cava