10. With reference to the fetal circulation and ch

[Editor]

10. With reference to the fetal circulation and changes at birth:
a. before birth oxygen tension in the ductus arteriosus is greater than in the ductus venosus
b. before birth oxygen tension in the descending aorta is less than in the aortic arch
c. after birth closure of the foremen ovale is due to a reversal of the pressure gradient between the right and left atria
d. reversal or cessation of blood flow through the ductus arteriosus after birth is caused by the increase in pulmonary arterial pressure occurring at birth
e. Fetal blood can pass from the venae cavae to the aorta without passing through the left atrium or left ventricle

[jijindr]

a)t
b)t
c)t
d)t- pul vasculature resistance falls, pul vascular pressure increases.
e)t - r atrium-pul artery - dec aorta through ductus arteriosus

[drvp]

a) F b) T c) T d) F e) T

Ductus venosus carries oxygenated blood from the umbilical vein bypassing the liver, whereas ductus arteriosus carries deoxygenated blood predominantly from the SVC directly to the descending aorta bypassing the left side of the heart.

Reversal of blood flow in the ductus arteriosus after birth is due to fall in pulmonary vascular pressure due to expansion of lungs and rise in systemic vascular pressure.