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Flashcards in Gestation and Birth Deck (18)
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What diffuses between mother and embryo?

-diffusion occurs at placenta
-amino acids
-inorganic salts


Does maternal blood or fetal blood have a higher partial pressure of O2?

maternal blood (high partial pressure allows for diffusion to lower partial pressure found in fetal blood)


Describe fetal hemoglobin (HbF)

-found in fetal blood cells
-have greater affinity for oxygen compared to maternal Hb


Where does gas exchange/oxygenation occur in a fetus?

across the placenta because fetal lungs do not function until birth


What is the function of the placental barrier?

-immune protection (fetus is immunologically naive but accident exposure to pathogens can happen in utero)


What hormones are produced by the placenta?

-human chorionic gonadotropin (hCG)


Describe the umbilicial arteries

-carries deoxygenated blood AWAY from the fetus and TOWARDS the placenta
-also carries waste products


Describe the umbilical vein

carries oxygenated blood with nutrients TOWARDS the fetus and AWAY from the placenta


What are some key differences between fetal circulation and adult circulation?

-lung and liver are not significant prior to birth
-gas exchange occurs at placenta rather than lungs
-detoxification and metabolism primarily controlled by mothers liver
-nutrient and waste exchange occurs at placenta
-fetal lungs and liver are underdeveloped and sensitive to high BP
-right side of fetal heart has a higher pressure than the left side of the heart (opposite in adults)


What are shunts?

-developed by the fetus to direct blood away from fetal lungs and liver during development
-3 shunts: foramen ovale, ductus arteriosus, ductus venosus


What vessels/chambers does the foramen ovale connect?

-connects right atrium to the left atrium meaning that blood from the vena cava enters the right atrium and skips the right ventricle so blood is pumped thru aorta directly to systemic circulation
-allows the lungs to be bypassed


What vessels/chambers does the ductus arteriosus connect?

-connects pulmonary artery to aorta
-allows the lungs to be bypassed


What vessels/chambers does the ductus venosus connect?

-connects the umbilical vein to the inferior vena cava
-allows the liver to be bypassed


What happens during first trimester?

-organogenesis occurs (development of heart, eyes, gonads, limbs, liver, brain)
-cartilaginous skeleton begins to harden into bone
-embryo is known as a fetus by the end of 8 weeks


What happens during second trimester?

-fetus undergoes tremendous growth
-fetus begins to move within amniotic fluid
-face takes on a human appearance
-toes and fingers elongate


What happens during third trimester?

-rapid growth and brain development continue
-transfer of antibodies to fetus


What is parturition?

-vaginal childbirth
-accomplished by rhythmic contractions of uterine smooth muscle which is coordinated by prostaglandins and oxytocin


Describe the 3 phases of birth

1. cervix thins out and amniotic sac ruptures
2. strong uterine contractions lead to birth of fetus
3. placenta and umbilical cord are expelled (afterbirth)