fetal circulation

Question 1

ductus venosus

Answer 1

shunt connects umbilical vein to inferior vena cava

allows blood to bypass liver

Question 2

foramen ovale

Answer 2

shunt connects R atrium with L atrium

allows blood to bypass R ventricle and pulmonary circulation

Question 3

ductus arteriosus

Answer 3

connects pulmonary artery with aorta

allows blood to bypass pulmonary circulation

Question 4

at birth: what happens to pulmonary vascular resistance

Answer 4

it decreases

Question 5

at birth: why does foramen ovale close

Answer 5

due to fall in pulmonary resistance, the pressure in R atrium falls
L atrial pressure > R atrial pressure which squashes atrial septum causing closure foramen ovale

Question 6

at birth: closure ductus arteriosus

Answer 6

prostaglandins are required to keep ductus arteriosus open

increased in blood oxygen caused decrease in prostaglandins –> closure of ductus arteriosus

Question 7

at birth: closure ductus venosus

Answer 7

stops functioning as umbilical cord is clamped and there is no flow through umbilical veins