Fetal Circulation Flashcards
All the capillaries and vessels are formed in
The 4th week
Umbilical arteries
Are arteries that carries deoxygenated blood from the fetus to the placenta
Umbilical veins
carries oxygenated from the placenta to the fetus
There are three shunts
Ductus venosus
Ductus arteriosus
Foramen ovale
The Ductus venosus
Shunts the umbilical veins away from the liver into the inferior vena cava.
Ductus arteriosus
Shunts the pulmonary trunk(artery) away from the lungs into the umbilical arteries
Foramen ovale
Shunts blood from the right atrium to the left atrium
Blood pressure In the umbilical vein
15-20mmHg
In the fetal lung
There is high respiratory resistance
The lungs is
Filled with fluids which is responsible for the high respiratory resistance
Ductus arteriosus after birth
Becomes ligamentum arteriosus
Ductus venosus after birth becomes
Ligamentum venosus
Foramen ovale after birth becomes
Fossa ovalis
Functional closure of the ductus venosus is
Immediately after birth
Structural closure of ductus venosus occurs
3-7 days after birth
Closure of ductus venosus is due to
Unknown cause
It is the strong contraction of the wall of the ductus venosus
Closure of the ductus arteriosus is due to
Contraction of the smooth muscle in its wall caused by reverse flow of blood into the pulmonary trunk.
This is caused by increased oxygen availability.
The events that happened after birth
Umbilical arteries becomes umbilical ligaments
Umbilical vein becomes ligamentum teres
Blood pressure In the right side reduces
Blood pressure in the left side increases
Lungs replaces placenta as the respiratory resistance reduces
Oxygen increases to 100mmHg
Left part of the heart gets thicker than the right part
