CARDIOVASCULAR III
FETAL CIRCULATION
Left umbilical vein persists and carries oxygenated blood from placenta to liver
Half goes to liver
(Less Oxygenated)
Half gets shunted through ductus venosus to IVC
(More Oxygenated)
Blood from IVC
Directed by crista dividens (inferior border of septum secundum)
Goes through foramen ovale and into left atrium
This blood goes to brain and upper extremities
Remaining Blood (Less oxygenated from IVC & deoxygenated from upper body)
SVC  Rt. Atrium  Rt. Ventricle  Pulm. Artery 
Ductus Arteriosus  Lower Body
UPPER BODY RECEIVES MORE OXYGENATED BLOOD THAN LOWER BODY
Changes at Birth
1.
Breathing
Lungs Expand and become functional
Ductus Arteriosus Constricts and Closes (via bradykinin)
Ductus Arteriosus

Ligamentum Arteriosus
Anatomical Closure of Duct occurs by 3rd Month
Aeration of Lungs:
1.
Stretching/Thinning of Walls of Pulmonary Arteries
2.
Dramatic Fall in Pulmonary Vascular Resistance
3.
Right Ventricular Wall becomes thinner than Left Ventricle
2.
More blood Reaches Let Atrium through Pulmonary Veins
3.
Ductus Venosus 
Ligamentum Venosus
4.
Closure of Foramen Ovale due to increased pressure of #2
5.
Umbilical Cord is Cut:
a. Umbilical arteries
proximal part

Superior Vesical Arteries
Distal part

Medial Umbilical Ligaments
b. Umbilical Veins
Ligamentum Teres Hepatis
Umbilical Vein remains patent and can be used for blood transfusions.