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What is Which of these changes in fetal circulation happen immediately at bih? and explain in detail?
No anatomical closure or obliteration of either ductus venosus, or umbilical vein or foramen ovale occurs immediately at bih. It is only functional closure of these, that results from expansion of lungs at bih and lowering of resistance of pulmonary vasculature that results in change of blood flow pattern through hea from parallel to series like that in adults. Shunt/ vessel Functional closure Anatomical closure Remnant called as Ductus venosus 10-96 hrs after bih 2-3 weeks after bih Ligamentum venosum Ductus aeriosus At bih Several weeks after bih Ligamentum aeriosum Foramen ovale At bih 1 year after bih Fossa ovalis Umbilical vein Ligamentum teres Distal hypogastric aeries Umbilical ligaments