Fetal circulation:

Question 1

Fetal circulation

Answer 1

1) Maternal oxygenated blood —> Placenta —> Through umbilical vein —> Goes to liver —> Most of blood goes through ductus venosus ( some goes to hepatic sinusoids ) —> SVC —> RA

2) High PVR due to fluid in immature lungs, therefore blood doesn’t go to lung.

Instead, both:

RA —> Foramen ovale —> LA —> LV —> Aorta —> Systemic circulation

RA —> RV —> P. Artery —> Through Ductus Venosus —> Into Aorta —> Systemic circulation

Question 2

Circulation + Pulmonary adaption

Answer 2

CIRCULATION:

Fetus descends through birth canal —> Infant chest is squeezed so fluid from lungs is drained —> 1st breast sounds after delivery —> Decrease in PVR —> Increased LA filling and pressure —> F. Ovale + D. Arteriosus close

PULMONARY

1st breath sounds after delivery —> Surfactant is produced by type 2 alveolar cells —> Decreases Surface tension of alveolar and prevents from collapsing

Question 3

Temp adaptation:

1) Why are newborns at risk of hypothermia?

2) How do newborns adapt for temp

Answer 3

1)
- Large SA relative to BW

• Quick evaporation of amniotic fluid from skin
• Immature thermoregulation ( can’t shiver )

2)
- Brown fat ( found on upper back, neck and shoulders, around kidneys ) metabolism —> generates heat

• Immediate drying with warm towel
• Immediate skin to skin contact with mum in kangaroo care position