Foetal Circulation Flashcards
What are the three shunts in the foetal circulation?
Ductus venous
Foremen ovale
Ductus arteriosus
What is the function of the ductus venosus?
To shunt oxygenated blood from the umbilical vein to the IVC bypassing the liver
What is the adult remnant of the ductus venosus?
Ligamentum venosum
The umbilical vein drains in to which structure?
Inferior vena cava (IVC(
What is the adult remnant of the umbilical vein?
Ligamentum teres
Which vessels are found within the umbilical cord?
Two umbilical arteries
One umbilical vein
The umbilical arteries arise from which structure?
Internal iliac arteries
What is the adult remnant of the umbilical arteries?
Medial umbilical ligaments
What is the significant of an umbilical cord containing only one umbilical artery?
Occurs in 1%
Of those, 20% will have co-existing vessel or heart abnormality
What is the function of the ductus arteriosus?
Connection between pulmonary artery and aorta
Allows oxygenated blood to bypass the lungs
Which substances maintain the ductus arteriosus?
Prostaglandins (in particular prostaglandin E2)
Which substances close the ductus arteriosus?
Prostaglandin antagonists e.g. NSAIDs
What is the most important chemical for maintaining a patent ductus arteriosus during pregnancy?
PGE2
What happens to the foetal shunts at birth?
Flap closure of the foramen ovale
Functional closure of the ductus arteriosus and venosus
What causes closure of the ductus arteriosus at birth?
Increased arterial pO2
Increased bradykinin
Decreased prostaglandin E2
