Fetal Development Flashcards

1
Q

what is the ductus venosus

A

fetal blood shunt which bypasses the liver

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2
Q

why is the ductus venosus important

A

the liver is very metabolically active so will use up the oxygen in the umbilical veins on the way to the heart

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3
Q

what is the ductus arteriosus

A

fetal blood shunt causing blood to move from the pulmonary trunk into the aorta

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4
Q

why is the ductus arteriosus important

A

to bypass the lungs as these are not functional

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5
Q

what is the foramen ovale

A

fetal blood shunt, moving blood from the RA to LA

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6
Q

why is the foramen ovale important

A

to bypass the lungs and RV

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7
Q

what factors allow for an increase in the pO2 gradient between the mother and fetus

A
  • increase in maternal pO2 through hyperventilation
  • increase in maternal 2,3-BPG
  • fetal haemoglobin
  • double Bohr effect
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8
Q

how does a increase in maternal 2,3-BPG increase the pO2 gradient

A

it means at the placenta there is a loss of affinity of Hb for oxygen so more is given up, producing a high pO2 in maternal blood

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9
Q

how does fetal haemoglobin produce an increase in the pO2 gradient

A

it has a higher affinity for oxygen so there will be less oxygen in the fetal blood, keeping the pO2 lower

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10
Q

describe the double Bohr effect

A
  • the CO2 from the fetus causes a decrease of pH in the mother, this causes a loss of affinity of the Hb for oxygen
  • in the fetus the loss of CO2 increases the pH which causes an increase in affinity of the Hb to oxygen
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11
Q

what happens to the heart rate in fetal hypoxia

A

it slows down

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12
Q

what is normal fetal heart rate

A

110-160 bpm

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13
Q

what are the 2 types of growth restriction

A

asymmetrical and symmetrical

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14
Q

what is symmetrical growth restriction

A

where the baby is smaller but the body is proportionally smaller

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15
Q

what is asymmetrical growth restriction

A

where the head/abdomen may be bigger or smaller resulting in not normal proportions

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16
Q

why does physiological jaundice occur at birth

A

as the liver must mature to conjugate and excrete the bilirubin as the mother did this previously

17
Q

what birth weight does growth restriction class as

A

under 2500g

18
Q

what is it known as when the birth weight is above 4500g

A

macrosomia

19
Q

give a cause of macrosomia

A

gestational/maternal diabetes

20
Q

give some ways of assessing ante-natal development

A
  • 20 weeks fetal movement can be detected
  • symphsis-fetal height
  • ultra sound
  • doppler ultra sound (see placental flow)
  • crown rump length
  • femur length
  • biparietal circumference
  • abdominal circumference
21
Q

how is the amniotic fluid produced after 9 weeks

A

through the urine production by the fetal kidneys

22
Q

how is amniotic fluid recycled

A
  • inhaled by the fetus

- swallowed by fetus

23
Q

what does inhaling the amniotic fluid result in

A

development of the lungs

allows the lung muscles to start moving preventing atrophy

24
Q

what happens to the swallowed amniotic fluid

A

it is absorbed through the GI tract

25
what happens to the amniotic fluid which is not absorbed by the GI
it is combined with the secreted fetal bile to form meconium
26
what happens to the meconium in fetal stress
it is prematurely released
27
what part of the primitive gut tube does the respiratory system develop from
foregut
28
what separates the GI tract and the respiratory tract
tracheoesphageal septum
29
what is fetal bradycardia associated with
hypoxia
30
what is it called when there is too little amniotic fluid
oliohydramnios
31
what is it called when there is too much amniotic fluid
polyhydramnios
32
give some reasons for oligohydramnios
placental insufficiency, maternal hypertension, bladder outlet obstruction
33
give some reasons for polyhydramnios
CNS problems with swallowing, blind ended oesophagus, poor positioning of the tracheoesphageal septum
34
when does myelination of the brain begin
after birth
35
how can premature birth cause respiratory distress syndrome
not enough surfactant may be produced
36
when is the majority of surfactant produced
week 34
37
when do the alveoli appear (terminal stage f respiratory development)
26 weeks