Foetal Circulation Flashcards
2 stages of blood vessel development
vasculogenesis
angiogenesis
how and when do conorary arteries develop
developed in week 7
epicardial cells transition to mesenchymal cells
these cells differentiate into smooth muscle and endothelial cells of conorary arteries which end up coonecting to the aorta
systemic arterial/venous system dominant side
arterial is left side dominant
venous is right side dominant
vitelline vessels
vitelline arteries are branches of the dorsal aortae that supply the yolk sac from the systemic arterial system
vitelline veins forms a plexus around duodenum. it becomes superior mesenteric vein-portal vein-hepatic sinusoids- hepatocardiac portion of IVC which drains into sinus venousus
where does the fetus get oxygenated blood from
from the mother via the placenta
maternal arteries in the placenta make part of the chorionic villi and then exit placenta as umbilical vein
how does the embryo get oxygenated blood into its systemic venous system
through liver sinusoids
through venous shunt of the ductus venosus
path of blood through fetal heart
oxygenated blood enter right atrium via IVC
it can then eith travel down to right ventricle or travel across to left atrium(fetal shunt)
why is going through left atrium the path of least resistance
because alveoli are not filled with air pulmonary circulation vasoconstricts due to hypoxia
this means pressure in right side of heart is higher than left
so blood naturally travels from higher pressure to lower
what is the third shunt
not all the blood travels to the aorta through the heart
some blood moves through a shunt from the pulmonary artery directly to the aorta
where does the blood go after the aorta
goes from descending aorta to R/L common iliac
which extends to R/L internal/external iliac
both R/L internal iliac goes into umbilical arteries
both R/L external iliac goes to the rest of the embryo
what happens when baby is born and takes first breath
alveoli fills with air which stops hypoxia in pulmonary circulation which causes vasodilation so pressure on left becomes higher than right
foramen ovale and ductus arteriosus close
umbilical arteries and veins functionally close and umbilical chord is cut as it is now useless
