Fetal Circulation

Umbilical, vitelline, cardinal vv

Three sets of veins of the mammalian heart

Ventral aorta

Continuous with the heart and joins an independently formed dorsal aorta by a system of aortic arches lateral to the pharynx

Dorsal aorta

Independently formed; joined by ventral aorta by a system of aortic arches lateral to the pharynx

Aortic arches 1-2

Which aortic arches disappear?

Maxillary arteries

The remnants of the aortic arches help to form the ___ in the head.

Third aortic arch

Aortic arch that forms the common carotid aa.

Fourth aortic arch

Aortic arch

Right forms the proximal segment of the right subclavian a.

Left forms the actual aortic arch

Fifth aortic arch

Which aortic arch is only present in reptiles?

Sixth aortic arch

Aortic arch

Left forms the pulmonary trunk / ductus arteriosus

Placenta

Combines the roles of the lungs, digestive tract, and kidneys

Umbilical v

Vessel in which oxygen- and nutrient-rich blood is provided to the fetus

Umbilical aa

Vessels in which oxygen- and nutrient-deficient blood is returned to the placenta

Placenta —> umbilical v —> liver and ductus venosus —> caudal vena cava —> right atrium

Blood flow from placenta to right atrium

Right atrium —> right ventricle —> pulmonary trunk —> pulmonary aa —> lungs

Postnatal flow from right atrium (offers high resistance)

Right atrium —> right ventricle —> pulmonary trunk —> ductus arteriosus —> thoracic aorta

Postnatal flow from right atrium (no resistance)

Right atrium —> foramen ovale —> left atrium —> left ventricle —> aortic arch —> thoracic aorta

Alternate flow path from right atrium (low resistance)

Ligamentum arteriosum

Ductus arteriosus converts to this after increased oxygen tension stimulates contraction