Fetal Development. RC 290. The Placenta. Purple and pancake shaped 6 inch diameter, 1 inch thick 13-16 square meter surface area. Attaches to upper 1/3 of uterus Maternal side: Decidua Basalis Fetal side: Chorion (attaches to amniotic membrane). Placental Structure. Placental Functions.
Note: Maternal and fetal blood do not come into direct contact!
Hence, fetal PO2 is 25-30 mmhg!
OOOPS! This is fecal circulation!
Most of blood shunts across the Ductus Venosus into the inferior vena cava
As inferior vena cava empties into right atrium, most blood shunts across the Foramen Ovale into the left atrium where it enters the systemic circulation from the left ventricle
The heart and brain get the best blood first!
Blood from superior vena cava goes into right ventricle and then to pulmonary artery
Most of this blood flow shunts across the Ductus Arteriosus into the aorta
DA is in the descending aorta after the arch
Pre-ductal blood may have a higher PO2!
Hence, only 3-10% of fetal cardiac out put perfuses the fetal lingsFetal Circulation
Is a phospolipid made up of dipalmityl-lecithin and sphingomyelin
Produced through two enzymatic pathways:
This is the major pathway and has a longer half-life