Quiz 6

Question 1

what is PaO2 of fetus

Answer 1

20-30 mmHg

Question 2

3 fetal adaptations to hypoxia

Answer 2

1. specialized circulation
2. Increased blood affinity for oxygen (fetal hemoglobin)
3. Increased [Hgb] and combined cardiac output

Question 3

is oxyhemoglobin saturation higher or lower in the fetus than the adult

Answer 3

lower by 25%

Question 4

Is oxygen content of the mother higher or lower than fetus

Answer 4

similar

Question 5

ductus arteriosus moves blood that got into the _____ to the _____

Answer 5

right ventricle and pulmonary artery to the aorta

Question 6

relationship between placental blood flow and pulmonary blood flow

Answer 6

inverse

as pulmonary flow goes down, placental flow goes up

Question 7

hemodynamics in fetus is largely influenced by

Answer 7

high pulmonary vascular resistance

Question 8

Is the placenta more or less efficient than the lung at gas exchange

Answer 8

less

Question 9

what 3 things make the placenta more/less efficient than the lung

Answer 9

1. 10 to 20% more O2 exchanged per unit weight in the lung
2. placenta consumes 50% of available oxygen
3. 20-35% of available blood flow functionally bypasses gas exchange sites

Question 10

5 factors that affect placental gas exchagne

Answer 10

1. area
2. blood flow to the maternal side of the placenta
3. fetal blood flow (relatively high CVO)
4. Oxygen content of maternal blood
5. Reltaive affinities of fetal and maternal hemoglobin

Question 11

Fetal Hgb is present at what week of gestation

Answer 11

12 weeks

Question 12

fetal hgb makes up what % of total hgb

Answer 12

75-85

Question 13

p50 for fetal hemoglobin is higher or lower than maternal

Answer 13

lower

Question 14

why does fetal hemoglobin bind oxygen more tightly than maternal/adult hemoglobin

Answer 14

doesn’t bind 2, 3 DPG as well

Question 15

what is implication of steeper curve for fetal hemoglobin

Answer 15

allows release of oxygen w/ small changes in PaO2

Question 16

describe double Bohr effect

Answer 16

• 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

Question 17

double Bohr effect accounts for what % of O2 exchange

Answer 17

8

Question 18

double haldane effect accounts for what % of CO2 exchange?

Answer 18

46%

Question 19

Which part of GI is developed during first 16 weeks of gestation

Answer 19

conducting/airways and arterioles

Question 20

does vascular muscle thickness of lungs increase/decrease during late development and what is the implication of this?

Answer 20

decrease–this decreases PVR

Question 21

main contributor to PVR

Answer 21

low O2, high pH

Question 22

t/f fetal lung fluid is derived from amniotic fluid

Answer 22

f–made in lungs

Question 23

what 2 things are essential for lung growth?

Answer 23

maintenance of lung volume and fetal breathing

Question 24

3 groups of changes that take place during the transition from fetal to neonatal life

Answer 24

changes in circulation
establishment of air breathing
surfactant

Question 25

What are the two contributing factors to decrease PVR at birth

Answer 25

stretch and O2

Question 26

What two factors allows ductus arteriosus to close

Answer 26

``` oxygenation decrease PGE (prostaglandins) ```

Question 27

which shunt closes the fastest, slowest

Answer 27

ductus venosus | foramen ovale

Question 28

3 main stimuli for first breath?

Answer 28

temperature drop gravity stress--chatecholines

Question 29

What makes breathing continuous

Answer 29

reduction in inhibition

Question 30

3 things that remove fetal lung fluid

Answer 30

1. labor 2. delivery 3. circulation and lymphatics

Question 31

3 ways babies maintain FRC

Answer 31

Expiratory braking maneuver crying grunting

Question 32

t/f newborns breakdown their surfactant

Answer 32

f

Question 33

mutations in SP-B gene cause what

Answer 33

fatal

Question 34

mutations in SP-C gene cause what

Answer 34

variable and severe interstitial lung disease in infants

Question 35

components of surfactnat appear in amniotic fluid when

Answer 35

34-36 weeks gestation

Question 36

4 mechanical disadvantages of the neonatal chest/lung

Answer 36

1. more circuluar --less bucket handle 2. diaphragm is less domed/more flattened 3. High compliance 4. disadvantage is accentuated when supine