Quiz 6 Flashcards
what is PaO2 of fetus
20-30 mmHg
3 fetal adaptations to hypoxia
- specialized circulation
- Increased blood affinity for oxygen (fetal hemoglobin)
- Increased [Hgb] and combined cardiac output
is oxyhemoglobin saturation higher or lower in the fetus than the adult
lower by 25%
Is oxygen content of the mother higher or lower than fetus
similar
ductus arteriosus moves blood that got into the _____ to the _____
right ventricle and pulmonary artery to the aorta
relationship between placental blood flow and pulmonary blood flow
inverse
as pulmonary flow goes down, placental flow goes up
hemodynamics in fetus is largely influenced by
high pulmonary vascular resistance
Is the placenta more or less efficient than the lung at gas exchange
less
what 3 things make the placenta more/less efficient than the lung
- 10 to 20% more O2 exchanged per unit weight in the lung
- placenta consumes 50% of available oxygen
- 20-35% of available blood flow functionally bypasses gas exchange sites
5 factors that affect placental gas exchagne
- area
- blood flow to the maternal side of the placenta
- fetal blood flow (relatively high CVO)
- Oxygen content of maternal blood
- Reltaive affinities of fetal and maternal hemoglobin
Fetal Hgb is present at what week of gestation
12 weeks
fetal hgb makes up what % of total hgb
75-85
p50 for fetal hemoglobin is higher or lower than maternal
lower
why does fetal hemoglobin bind oxygen more tightly than maternal/adult hemoglobin
doesn’t bind 2, 3 DPG as well
what is implication of steeper curve for fetal hemoglobin
allows release of oxygen w/ small changes in PaO2
describe double Bohr effect
- on maternal side, the CO2 causes the O2 disassociation curve to shift to the right
- on the fetal side, the release of CO2 causes the disassociation curve to shift to the left
double Bohr effect accounts for what % of O2 exchange
8
double haldane effect accounts for what % of CO2 exchange?
46%
Which part of GI is developed during first 16 weeks of gestation
conducting/airways and arterioles
does vascular muscle thickness of lungs increase/decrease during late development and what is the implication of this?
decrease–this decreases PVR
main contributor to PVR
low O2, high pH
t/f fetal lung fluid is derived from amniotic fluid
f–made in lungs
what 2 things are essential for lung growth?
maintenance of lung volume and fetal breathing
3 groups of changes that take place during the transition from fetal to neonatal life
changes in circulation
establishment of air breathing
surfactant
What are the two contributing factors to decrease PVR at birth
stretch and O2
What two factors allows ductus arteriosus to close
oxygenation decrease PGE (prostaglandins)
which shunt closes the fastest, slowest
ductus venosus
foramen ovale
3 main stimuli for first breath?
temperature drop
gravity
stress–chatecholines
What makes breathing continuous
reduction in inhibition
3 things that remove fetal lung fluid
- labor
- delivery
- circulation and lymphatics
3 ways babies maintain FRC
Expiratory braking maneuver
crying
grunting
t/f newborns breakdown their surfactant
f
mutations in SP-B gene cause what
fatal
mutations in SP-C gene cause what
variable and severe interstitial lung disease in infants
components of surfactnat appear in amniotic fluid when
34-36 weeks gestation
4 mechanical disadvantages of the neonatal chest/lung
- more circuluar –less bucket handle
- diaphragm is less domed/more flattened
- High compliance
- disadvantage is accentuated when supine
