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.AdvPrin A - Spr25 > Uteroplacental & Fetal Physiology Pt. 3 (Exam 2) > Flashcards

Uteroplacental & Fetal Physiology Pt. 3 (Exam 2) Flashcards

1
Q

What are the following abbreviations?
* MVU
* TOCO
* IUPC
* FSE
* CPD
* BPP

A
  • MVU = Montevideo Units
  • TOCO = Tocodynamometer
  • IUPC = Intrauterine Pressure Catheter
  • FSE = Fetal Scalp Electrode
  • CPD = Cephalopelvic Disproportion
  • BPP = Biophysical Profile
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2
Q

What are the following abbreviations?
* DA
* DV
* FO
* HbF
* HbA
* FHR

A
  • DA = Ductus Arteriosus
  • DV = Ductus Venosus
  • FO = Foramen Ovale
  • HbF = Fetal Hemoglobin
  • HbA = Adult Hemoglobin
  • FHR = Fetal Heart Rate
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3
Q

In fetal circulation, oxygen exchange occurs in the _____ instead of the lungs?

A

Placenta (organ of gas exchange)

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4
Q

Fetal circulation is ______ in contrast to adult circulation which is _____ _____.

A

parallel : in series

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5
Q

What are the three anatomic communications in fetal circulation?

A
  • Ductus Venosus
  • Foramen Ovale
  • Ductus Arteriosus
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6
Q

Pulmonary vascular resistance is ____ in fetus. Why is this?

A

High PVR

  • Fetal lungs are collapsed & filled with fluid.
  • very little pulmonary circulation.
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7
Q

Systemic Vascular Resistance is _____ in the fetus. Why?

A

Low

  • Placenta has a low resistance vascular bed.
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8
Q

Fetal hgb has a ____ affinity for oxygen than adult hgb? This leads to what?

A

high affinity for oxygen

  • efficient oxygen extraction from maternal blood
  • optimizes oxygen supply
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9
Q

The umbilical ____ brings oxygenated blood from the placenta to the fetus.

A

umbilical vein (1).

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10
Q

The umbilical _____ send deoxygenated blood form the fetus back to the placenta.

A

umbilical arteries (2).

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11
Q

What is the PO₂ of maternal blood in the placenta?
What is the (typical) O₂ saturation of the maternal blood?

A

PO₂ = 30-35 mmHg
SaO₂ = 80-85%

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12
Q

How does the fetus maintain adequate oxygenation when exposed to a “low” O₂ saturation?

A

HbF will preferentially pull O₂ from the mom’s HbA due to its higher affinity.

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13
Q

What are the cardiac output contributions of the right ventricle and left ventricle of the fetus?

A

RV = 67% of CO
LV = 33% of CO

Parallel circulation: both side of the heart provide systemic blood flow (not in-series like adults).

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14
Q

Which fetal vessel allows oxygenated blood from the placenta to bypass portal circulation and go straight to the inferior vena cava?

A

Ductus Venosus

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15
Q

Oxygenated and deoxygenated blood from the fetus’s lower and upper body mixes in the _____ before entering the _____?

A

Oxygenated and deoxygenated blood from the fetus’s lower and upper body mixes in the IVC before entering the Right atrium

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16
Q

What aspect of fetal circulation allows oxygenated blood to flow from the Right atrium to the Left atrium?
What does this bypass?

A

Foramen Ovale (FO)

  • Allows bypass of immature fetal lungs.

some blood goes into the right ventricle and into the immature pulmonary circulation

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17
Q

What causes the high right-to-left shunt of the foramen ovale?

A

Due to pressure gradient from high fetal PVR.

fetal lungs are filled with amniotic fluid => high PVR

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18
Q

What vessel diverts blood away from underdeveloped lungs?

A

Ductus Arteriosus: connects the pulmonary artery to descending aorta

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19
Q

How much of the blood that goes from the RV to the PA ends up going through the pulmonary circulation?

A

only about 10%

20
Q

What fetal blood vessel connects the pulmonary artery and the descending aorta?

A

Ductus Arteriosus

21
Q

How much blood passes from the pulmonary artery through the ductus arteriosus to the _____?

A

about 90% of blood that travels from the RV to PA reroutes through the ductus arteriosus to the descending aorta

this perfuses the lower body of the fetus

22
Q

What vessel carries oxygenated blood from the placenta to the fetus?

A

Umbilical Vein (80-85% saturated)

23
Q

What vessel carries deoxygenated blood from the fetus to the placenta?

A

Umbilical arteries

24
Q

Where does blood from the umbilical vein go?

A
  • ~50% to fetal portal circulation
  • ~50% bypasses portal circulation through DV to IVC.
25
Q

The percentage of umbilical vein blood directed to the liver will increase in conjunction with ______ ____.

A

gestational age

26
Q

Does all blood from the RA bypass the lungs and go directly into the left atrium via the FO?

A

No. Some blood from the RA will go to the RV and then immature pulmonary circulation.

27
Q

Describe the path for most of the blood through fetal circulation.

A

RA → FO → LA → LV → Aorta → systemic circulation.

28
Q

What is greater in a fetus, PVR or SVR?

29
Q

The majority of fetal blood passes from the pulmonary artery through the ____ to the descending aorta to perfuse the lower body of the fetus.

A

DA (Ductus Arteriosus)

~90%

30
Q

Where do the umbilical arteries originate?

A

descending aorta (common iliac arteries)

31
Q

What does the Ductus venosus do?

A

Shunts blood from the liver to the heart

32
Q

What does the Ductus arteriosus do?

A

Shunts blood from pulmonary circulation to the ascending aorta.

33
Q

What portion of the autonomic nervous system develops first and is predominant throughout fetal life?

A

Parasympathetic system

34
Q

What are the main environmental factors affecting fetal baroreceptors and thus SNS output?

A

Maternal BP & stress

35
Q

When does respiratory effort begin after delivery?

A

~30 - 90 seconds after delivery

36
Q

What respiratory changes occur at birth?

A
  • ↓ Intrathoracic pressure = Air movement
  • Lung expansion = ↑ PaO₂ ↓ PaCO₂
  • ↑ pH & PAO₂ = ↓PVR
37
Q

What does the decreased PVR upon birth do to pulmonary blood flow?

A

↑ pulmonary artery flow = RV output shifts to lungs = ↑ pulmonary blood flow

38
Q

What does surfactant do?

A

↓ surface tension = prevention of alveolar collapse = increased lung expansion and oxygen exchange

39
Q

When does surfactant production start?

A

24 - 28 weeks gestation

40
Q

The ductus arteriosus will constrict and close due to _________.

A

increased O₂ levels

41
Q

Why does the foramen ovale close?

A

Closes due to LA pressure exceeding RA pressure (shortly after birth)

42
Q

What causes LA pressure to exceed RA pressure in a neonate?

A

Clamping of the umbilical cord ⇒ ↑SVR ⇒ ↑LAP ⇒ ↓ right-to-left shunt

43
Q

This vessel closes with the clamping of the umbilical cord due to an increase in IVC pressure.

A

Ductus Venosus (DV)

44
Q

What four factors can cause PVR to remain elevated after delivery?

A
  • Hypoxia
  • Acidosis
  • Hypovolemia
  • Hypothermia
45
Q

What drug class when used by a mom can cause premature constriction of the ductus arteriosus and thus persistent pulmonary hypertension of the newborn?

A

maternal NSAID use

46
Q

What things can lead to premature constriction of the Ductus arteriosus?

A
  • NSAIDs
  • Preterm births
  • ↑ PA pressure

.AdvPrin A - Spr25 (21 decks)

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