10.5 Fetal Circulation Flashcards

1
Q

Why are all the circulatory features present in the fetus and not in the adult necessary?

A

the fetus does not use its lungs for gas exchange

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2
Q

What happens to much of the blood entering the right atrium in the fetal circulation?

A

it is shunted into the left atrium through the FORAMEN OVALE between the two atria

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3
Q

What is the foramen ovale?

A

the flap dividing the left atrium from the right atrium of the heart

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4
Q

What happens to any blood that does enters the right ventricle and is pumped into the pulmonary trunk?

A

it’s shunted into the aorta by way of the ductus arteriosus

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5
Q

What is the ductus arteriosus?

A

structure of the heart associated with fetal circulation and provides a pathway for returning any blood that enters the right ventricle back to the aorta

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6
Q

Where does the blood within the aorta travel?

A

to various branches, including the iliac arteries

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7
Q

What do the iliac arteries do?

A

connect the umbilical arteries leading to the placenta

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8
Q

What occurs at the placenta?

A

exchange of gases and nutrients between maternal blood and fetal blood

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9
Q

What does the umbilical veins do?

A

carries blood that’s rich in nutrients and oxygen to the fetus

enters the liver and joins the ductus venosus which merges with the inferior vena cava

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10
Q

Where are the umbilical arteries and vein?

A

they run alongside one another in the umbilical cord which is tied off and cut at birth, leaving only the umbilicus (navel)

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11
Q

What is the most common cardiac defect in a newborn? What happens?

A

the persistence of the foramen ovale

  • once the umbilical cord has been severed and the lungs have expanded, blood enters the lungs in quantity
  • the return of this blood to the left side of the heart usually causes a flap to cover the opening
  • incomplete closure occurs in nearly 1/4 individuals
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12
Q

Why does passage of blood from the right atrium to the left atrium rarely occur?

A

either the opening is small or it closes when the atria contract

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13
Q

What is “blue baby”?

A

the passage of impure blood from the right side to the left side of the heart is sufficient to cause a “blue baby”

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14
Q

How can “blue baby” be corrected?

A

by threading a catheter into the heart and sealing the defect

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15
Q

What is the placenta?

A

structure that only functions before birth

  • when the child is born, the placenta becomes part of the afterbirth
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16
Q

Where is the placenta?

A

firmly attached to the uterine wall by the allantois and by fingerlike projections called the chorionic villi

17
Q

What does the placenta do?

A

functions in gas, nutrient, and wast exchange between the embryonic (later fetal) and maternal circulatory systems

18
Q

Where is the umbilical cord?

A

stretches between the placenta and the fetus

19
Q

Why is the umbilical cord the lifeline of the fetus?

A

it contains the umbilical arteries and vein which transport waste molecules (carbon dioxide and urea) to the placenta for disposal and take oxygen and nutrient molecules from the placenta to the rest of the fetal circulation system

20
Q

Why does the ductus arteriosus normally close?

A

endothelial cells divide and block off this duct

21
Q

What later transforms into connective tissue?

A

remains of the ductus arteriosus and part of the umbilical vein