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Yr 2 Sem 1 Repro > 7.1 Foetal Physiology > Flashcards

7.1 Foetal Physiology Flashcards

1
Q

What is foetal pO2?

A

4kPa

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2
Q

What factors increase foetal O2 content?

A

Foetal Hb variant

Increased foetal haematocrit

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3
Q

What factors promote oxygen exchange to the foetus at the placenta?

A

Increased maternal production of 2,3-DPG
Foetal Hb
Double Bohr effect

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4
Q

What is the increased maternal production of 2,3-DPG secondary to?

A

Physiological respiratory alkalosis of pregnancy

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5
Q

When is HbF the predominant form of Hb?

A

12 weeks to term

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6
Q

Describe the composition of HbF

A

2 alpha subunits, 2 gamma subunits

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7
Q

Why does HbF have a greater affinity for oxygen?

A

Because it doesnt bind 2,3-DPG as effectively as HbA

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8
Q

What is the double Bohr effect?

A

Bohr effect on maternal and foetal side
CO2 passes into intervillous blood, pH decreases, decreased affinity of Hb for O2
At the same time..
CO2 is lost, pH rises, increases affinity of Hb for O2

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9
Q

What is the advantage of the double Bohr effect?

A

Speeds up the process of oxygen transfer

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10
Q

How is a carbon dioxide concentration gradient maintained across the placenta?

A

Progesterone driven hyperventilation in mother

Lower pCO2 in maternal blood

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11
Q

Why are there no alterations in local pCO2 at the placenta?

A

As Hb gives up O2, it can accept increasing amounts of CO2

Foetus gives up CO as O2 is accepted (Haldane effect)

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12
Q

Why does the liver need to be bypassed in foetal circulation?

A

Because it is much larger in foetus than adult

Would consume all of the oxygen and nutrients

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13
Q

What does the ductus venosus connect?

A

Umbilical vein to IVC

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14
Q

Where does blood from the ductus venosus?

A

Right atrium

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15
Q

Why does blood flow through the foramen ovale into the LA?

A

Because right atrial pressure is greater than left atrial

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16
Q

What does the free borer of septum secundum form?

A

Crista dividens

17
Q

How many streams of blood flow are created by the FO?

A

2

18
Q

Where does the ductus arteriosus shunt to and from?

A

From RV and PT to aorta

19
Q

Where does the DA join?

A

Joins aorta distal to the supply of the head (and heart)

20
Q

Describe the foetal response to hypoxia

A

Redistribution of blood flow to head and heart

Heart rate slows (less oxygen demand)

21
Q

What sort of stimulation leads to bradycardia in the foetus upon detection of decreased pO2 of increased pCO2 by the foetal chemoreceptors?

A

Vagal

22
Q

What are the consequences of chronic hypoxaemia to the foetus?

A

Growth restriction

Behavioural changes which can impact on development

23
Q

What is the most common cause of foetal chronic hypoxaemia?

A

Smoking

24
Q

Which hormones are necessary for foetal growth?

A

Insulin, IGF1, IGF2, lepton, EGF, TGFa

25
Q

When is IGF1 dominant?

A

T2, T3

Nutrient dependent

26
Q

When is IGF2 dominant?

A

T1

Nutrient independent

27
Q

What is leptin involved in for foetal growth?

A

Placental production

28
Q

What is the dominant cellular growth mechanism at 0-20 weeks?

A

Hyperplasia

29
Q

What is the dominant cellular growth mechanism at 20-28 weeks?

A

Hyperplasia and hypertrophy

30
Q

What is the dominant cellular growth mechanism from 28 weeks to term?

A

Hypertrophy

31
Q

What are two functions of amniotic fluid?

A

Protection

Development of lungs

32
Q

When does a foetus start producing urine?

A

9 weeks

33
Q

What is the composition of amniotic fluid?

A

98% water

Plus electrolytes, creatinine, urea, bile pigments, renin, glucose, hormones and foetal cells, lanugo, vernix caseosa

34
Q

What is meconium?

A

Debris from AF plus intestinal secretions including bile

35
Q

What is amniocentesis?

A

Sampling of amniotic fluid
Allows for collection of foetal cells
Invasive

36
Q

What is amniocentesis useful for?

A

Diagnostic tests eg foetal karyotyping

37
Q

How is feotal bilirubin cleared during gestation?

A

By the placenta

38
Q

What can raw foetus not conjugate bilirubin?

A

Immature liver and intestinal processes for metabolism, conjugation and excretion

Yr 2 Sem 1 Repro (10 decks)

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