Basic Cardiac Embryology/circulatory Changes Flashcards
What provides a foetus with oxygenated blood?
Umbilical veins
Where does oxygenated blood enter the foetal heart?
Via caudal vena cava, into right atrium then passes to left via foramen ovale.
What is the ductus arteriosus?
Duct that allows liver to be bypassed
When young, the foramen ovale closes to become what?
Fossa ovalis
What is the ductus arteriosus?
Duct that connects aorta and pulmonary artery
Allows blood to mostly bypass the lungs
What provides the foetus with nutrition?
Yolk sac
Via vitelline veins
Why is the blood in the left atrium of the heart diluted?
It mixes with deoxygenated blood
What is the first stage of cardiac embryology?
Cells in mesoderm form blood islands
Blood islands join to become haemoblasts
Haemoblasts join to form cardiac tube
What happens to the umbilicus before/during birth?
Umbilicus arteries contract and elastic recoils
Prevent haemorrhage when ruptures
What does the umbilicus vein become
Round ligament of the liver
What does the umbilicus artery become
The round ligament of the bladder
What happens to circulation when taking a first breath?
Drop in resistance to pulmonary circulation. Capillaries in lungs open
Increased preload in left atrium and increased aortic pressure
Causes septum primum to be pushed against septum secundum - close foramen ovale
What happens to the ductus arteriosus during birth?
Smooth muscle constricts
Connective tissue fully closes it within months
When the ductus arteriosus closes, what does it become?
Ligamentum arteriosum
What would happen if the ductus arteriosus did not close?
Blood would flow the opposite way
Too much preload
