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Repro > Placenta Function > Flashcards

Placenta Function Flashcards

1
Q

When does the placenta develop?

A

Second week of development

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2
Q

Of which membrane is the placenta a specialisation of ?

A

Chorionic membrane

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3
Q

Briefly describe which layers are present during the week of 2s

A

Outer cell mass :syncytiotrophoblast and cytotrophoblast

Inner cell mass : epiblast and hypoblast

Amniotic cavity and yolk sac

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4
Q

When does implantation begins ?

A

Day 6

At initial contact between endometrium and trophoblast

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5
Q

What is the connecting stalk made of ?

A

Extraembryonic mesoderm

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6
Q

What happens to the yolk sac during development ?

A

Disappears, incorporated in proximal umbilical cord

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7
Q

What happens to the amniotic sac ?

A

Enlarges and surround all of the foetus , occupies all the chorionic cavity

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8
Q

What happens to the chorionic cavity ?

A

Is occupied by the amniotic sac

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9
Q

What does implantation achieve ?

A
  • Establishes the unit of exchange :villi
  • Anchor the placenta
  • Establish maternal blood flow to placenta
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10
Q

How do the villi develop ?

A

Primary villi : finger like projections of trophoblast
Secondary villi : invasion of mesenchyme into core
Tertiary villi : invasion of mesenchyme by fetal vessels

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11
Q

Does the maternal and foetal circulation mix ?

A

No never,

Separated by at least one layer of trophoblast

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12
Q

What is a chorionic villus ?

A

Basic unit of exchange , finger like projection of trophoblast containing fetal vessels

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13
Q

Which defect in placental implantation can occur ?

A

The wrong place : ectopic , placenta praevia

Incomplete invasion :
Placental insufficiency , pre eclampsia

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14
Q

How is invasion during implantation controlled ?

A

In presence of the conceptus, the endometrium becomes the decidua and the decidua leader reaction balance the invasive force

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15
Q

What is a cotyledon ?

A

Bulging villus area , surface covered by decidua basalis from uterine wall

Derived from foetal and mother tissue

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16
Q

What changes occur in the villus through the pregnancy ?

A

Gets thinner for optimal exchange , only one layer of syncytiotrophoblast and capillary endothelium

17
Q

Which blood vessels are contained in the umbilical cord ? How is the blood and where does it travel ?

A

2 umbilical arteries : deoxygenated blood from foetus to placenta
1 umbilical vein : oxygenated blood from placenta to foetus

18
Q

Describe the foetal circulation from the placenta to the foetal body

A

Placenta > umbilical vein > ductus venosus bypass liver > right atrium > foramen ovale > left atrium > systemic circulation with mixing with pulmonary trunk blood via ductus arteriosus

19
Q

Which hormones are produced by the placenta ?

A

Steroid hormones : progesterone , oestrogen

Peptide hormones :

  • human chorionic gonadotrophin
  • hC somatomammotrophin (aka human placental lactogen)
  • hC thyrotrophin
  • hC corticotrophin
20
Q

When is hCG produced and what is its function ?

A

First 2 months of pregnancy

Support the secretory function of the corpus luteum (oestrogen , progesterone )

21
Q

What produces hCG ?

A

Syncytiotrophoblast

22
Q

Which substance is used to test for pregnancy ?

A

Human chorionic gonadotrophin , made by syncytiotrophoblast

23
Q

When does the placenta takes over from the corpus luteum to produce steroid hormones ?

A

11th week

24
Q

What effect has progesterone on maternal metabolism ?

A

Increase appetite for nutrients for embryo and support lactation

25
Q

What effect does hCS aka hPL have on maternal metabolism ?

A

Increase glucose available for foetus by inducing insulin resistance in mother

26
Q

How does gas exchange occur in the placenta and how is it limited ?

A

Simple diffusion , flow limited so need an adequate uteroplacental circulation

27
Q

Which substances are actively transported by transporters expressed by syncytiotrophoblast ?

A

Amino acids , iron , vitamins

28
Q

Why is the placenta important for foetal immune system ?

A

Transfer of passive immunity by transfer of IgG by receptor mediated endocytosis

29
Q

Which pathophysiology can occur as a result of the placenta it being a true barrier ?

A
  • Teratogens can access foetus , influence development

- unintentional physiological response such as haemolytic disease of the new born due to rhesus

30
Q

What defects can thalidomide cause ?

A

Limb defects

31
Q

Which conditions are the consequences of alcohol ?

A

Foetal alcoholic syndrome

Alcoholic related neurodevelopment disorder

32
Q

Which drugs are contraindicated in pregnancy ?

A

ACEi
Anti epileptic drugs (valproate)
Warfarin

33
Q

Which stages of development are sensitive to teratogenesis ?

A

Pre embryonic : lethal effects
Embryonic period : very sensitive, systems specific
Foetal period : less , only growth is affected

Repro (10 decks)

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