Thorax 6: Fetal circulation Flashcards
Which vessels carry blood from the foetus to the placenta
2 umbilical arteries which branch from the internal iliac arteries
Which vessels are oxygenated in the umbilical cord
1 umbilical vein
what happens to the umbilical vessels after birth
arteries - medial umbilical ligaments
veins - ligamentum teres
what parts of foetal circulation are reduced compared to maternal circulation
pulmonary and hepatic
what bypasses the right ventricle and pulmonary trunk
foramen ovale
what is the purpose of the ductus arteriosis
redirects blood from the SVC that passes into the PT
It connects the ST to the inferior part of the aortic arch
how much blood from the RV is redirected
90%
what is the role of prostaglandins in the foetal circulation
patency of the ductus arteriosis
how does foetal blood bypass the liver
50% through the ductus venousus
where does the ductus venous empty
inferior vena cava
what kind of blood does the IVC contain the foetal circulation
a mixture of oxygenated placental blood and deoxygenated hepatic and systemic blood
what happens when a baby takes their first breath?
blood pushed into the pulmonary circulation and into the left atrium
atrial pressure equalises and foramen ovalis closes
what initiates the obliteration of the the ductus arteriosus
Rising O2 tension of blood in the aorta and PT after the first breath acts as a potent vasoconstrictor of the smooth muscle of the DA
where are prostaglandins removed
the lungs
prostaglandin and DA
fall in prostaglandin levels lead to closure of the DA
prostaglandin receptrors fall
