Fetal Circulation and Physiology- Topic 8 Flashcards
In the fetus, what organs do not function until birth?
Lungs
Kidneys
GI Tract
How does the fetus obtain oxygen and nutrients?
Via diffusion form the maternal blood
How are wastes and CO2 eliminated in fetal circulation?
Via diffusion into the maternal blood
How does exchange occur in fetal circulation?
Via the placenta, inside the uterus, attached to baby via the umbilical cord
Placenta
way of communication between mother nad baby
Umbilical Artery
carries blood away from the fetus to the placenta; carries wastes and CO2/ low O2 content
Umbilical Vein
carries blood from the placenta to the fetus; carries nutrients and O2; high O2 cotent
Fetal capillaries
umbilical arteries and veins branch into these capillaries located inside the intervillous spaces in the placenta
Intervillous spaces
spaces filled with maternal blood from uterine arterioles; drained by uterine veins
The placenta communicates with the mother’s cardiovascular system via what structure?
Uterine blood vessles
Wastes diffuse out of the capillaries into what spaces?
Intervillous spaces, containing maternal blood in the placenta
Nutrients travel from mother’s blood vessels to hte intervillous space via what structure?
uterine arteries; diffuse from intevillous spaces into the fetal capillaries
The concentration of hemoglobin in fetal blood is what percent higher than maternal blood
50%
Fetal hemoglobin has a _________(greater/lower) affinity for oxygen than maternal blood?
Greater
Fetal hemoglobin can carry what percent more oxygen?
30-35%
Is there direct mixing of maternal and fetal blood?
NO
Rogam Shot
attenuates the response of the Rh - mother against the Rh + baby
How many mls o2/min extracted?
20-30 mL
Placental circulation has low or high resistance?
Very low resistance
When does the fetus make components of complement? (the start of immunological competence)
Late first trimester
Fetal Immunoglobin Type
IgG
When are immunoglobulins transported from mother to fetus?
At about 14 weeks; provides passive immunity
When do newborns reach adult levels of IgG produced?
Age 3
When does the placenta produce enough progesterone to support pregnancy, should corpus leuteum fail?
4th month
Placenta continues to produce what estrogenic hormone?
Estriol, which rises until the end of pregnancy
Blood passes from the fetus to the placenta via what?
2 umbilical arteries; branch of the internal iliac arteries
Whats the saturation of the umbilical arteries?
~58%
Oxygenated blood is what saturation?
~80%
Oxygenated blood returns from the placenta via what?
1 umbilical vein
Oxygenated blood returning from the placenta goes to the liver of the fetus where it divides into what 2 branches?
Joins hepatic portal vein –> Liver (1/3)
Ductus venosus –> IVC (2/3)
*Sphincter mechanism in ductus tat controls blood flow through the liver
In the IVC, oxygenated blood via the ductus venosus meets deoxygenated blood form the lower body. Sat falls to what percent?
67%
What are the fetal lungs filled with?
Fetal lung fluid
Are the fetal lungs used to oxygenate blood?
No
What does the liquid in the fetal lungs do?
Increases pulmonary vascular restitance to blood flow
Most fetal blood does not go from the RV to lungs. Instead, it passes through what?
Foramen ovale
Foramen Ovale
Hole between the right and left atria
Blood entering from the IVC is guided toward the foramen ovale to where?
The LA
Pulmonary vascular resistance is so high that what percent of this blood bypasses hte pulmonary arteries?
95%
What are the 3 shunts present in the fetal circulation that normal close after birth?
Ductus Arteriosus
Formane Ovale
Ductus Venosus
When does complete closure of the umbilical arteries?
2-3 months
Autopsy shows what percent prevalence of PFO?
27%
When does the ductus arteriosus start to close? How long does it take?
Via vasoconstriction immediately after birth; takes about 1-2 days to close in a full term infant
How long does complete obliteration of the lumen take?
1-3 months
Umbilical Arteries become what?
Medial Umbilical Ligaments
Vein becomes?
Ligamentum Teres (Round ligament)
Ductus Venosus becomes what?
Ligamentum Venosum
Foramen Ovale becomes what?
Fossa Ovalis
Ductus Arteriosus becomes what?
Ligamentum Arteriosum