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CARDIO TEST 3 > Lecture 6: Role of Placenta in DOHAD > Flashcards

Lecture 6: Role of Placenta in DOHAD Flashcards

1
Q

What is transported through the placenta via diffusion?

A

Oxygen, steroid hormones, fetal waste

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2
Q

What are the features of facilitated diffusion via the placenta?

A

No ATP required, glucose moves through GLUT transporters

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3
Q

What are the features of active transport through the placenta?

A

ATP required, transports amino acids, folate and micronutrients

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4
Q

What are the most important amino acid transporters?

A

System A

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5
Q

What are the features of vesicular transport across the placenta?

A

Captured by microvilli and transport immunoglobulins

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6
Q

What is the glucocorticoid barrier?

A

Provides a gradient of glucocorticoids from the mother to the foetus

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7
Q

What gene is expressed in the placenta to convert active glucocorticoids to inactive metabolites and why is this necessary?

A

11B-HSD2 - important to convert things to avoid them passing through the placenta

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8
Q

What does neurokinin B do?

A

Binds to phosphocholines – (used by parasites to evade the immune system)

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9
Q

What types of cells does the placenta inhibit?

A

Maternal T-cells (lymphatic suppressors)

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10
Q

What antibodies cross the placenta?

A

IgG antibodies - provide immunity for the foetus during early life

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11
Q

What are some endocrine roles of the placenta?

A

Regulate maternal insulin levels, increase BG and FA, secrete progesterone

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12
Q

What are the roles of leptin/ghrelin?

A

Peptide hormones regulating maternal hunger/appetite

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13
Q

When does implantation occur?

A

Day 7/8

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14
Q

What is implantation?

A

Free-floating blastocyst comes into contact with uterine lining and invades it. Trophoblast forms placenta and inner cell mass forms fetus.

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15
Q

What is placentation?

A

The development of specialised regions of fetal and maternal origin, when maternal and zygote cells come within close proximity

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16
Q

When is placentation complete in humans?

A

End of 1st trimester

17
Q

What is placenta previa?

A

Occurs when placenta implants such that when it grows it covers the cervix, fetus has no passage to pass out through at childbirth - need hospital intervention for survival - require caesarean (1 in 200)

18
Q

What is placenta accreta?

A

Placenta invades far beyond the depth of what is considered normal and grows through the uterus and can invade beyond the uterus to structures such as the bladder - natural delivery would result in a severe amount of blood (placenta coming out and tearing away surrounding organs) - typically happens when women refuse any hospital/medical intervention during childbirth. If there is only partial accreta there may just be scarring. Usually uterus is completely removed and there is infertility after this (3 in 1000)

19
Q

What are the maternal layers that classify placentation?

A

Epitheliochorial, endotheliochorial, hemochorial

20
Q

What are the features of epitheliochorial?

A

A number of layers between the maternal and fetal blood supply - mother and fetus both have complete capillary networks and connect at a complex tree (whales, ruminants)

21
Q

What are the features of endotheliochorial?

A

Single layer between maternal and fetal blood supplies (carnivores) – one tree diminished

22
Q

What are the features of hemochorial?

A

Fetal capillaries sit in bath of blood - dilated blood spaces rather than individual capillaries (high order primates and rodents)

23
Q

How can the placenta be categorised by shape (what animals are these in)?

A
  • Diffuse – horse, placenta covers entire fetus
  • Multicotyledonary – sheep
  • Zonary – cat/dog
  • Discoid – human and mouse
24
Q

What are the types of fetal layers on the placenta?

A

Syncitiotrophoblasts, cytotrophoblasts - Mono (human), di or trichorial (rodent)

25
Q

What are the features of the rodent placenta?

A
  • Labyrinth: site of nutrient interchange with maternal and fetal interaction
  • More cell types with individual functions
  • Junctional zone: involved in hormone production, specialised for endocrine function
26
Q

What are the features of the human placenta?

A
  • Maternal blood bathes in chorionic villi
  • Villous: capillaries in maternal blood space to absorb nutrients
  • Extravillous: maternal uterus that interacts with the developing placenta
  • Vascular tree sits in pool of blood
27
Q

What are the effects of famine on placental size?

A
  • Babies were lighter, placentas had reduced SA and placental size more affected in boys
  • Offspring had glucose intolerance, coronary heart disease, increased stress responsiveness and obesity
28
Q

What is the importance of placental ratio?

A
  • For any given fetal body weight there is an optimal placental weight
  • If the placenta is more or less than 20% of the fetal weight it can be detrimental
  • Too large – inefficient placenta
  • Too small – poorly developed placenta
29
Q

What happens if there is an increased placental ratio?

A

Increased; BP, coronary heart disease, glucose intolerance

30
Q

What happens if there is a reduced placental ratio?

A

Increased coronary heart disease in men

31
Q

What are the common placental adaptations to maternal perturbations?

A
  • Impaired placental structure: altered SA for transport and nutrient supply
  • Dysregulated nutrient transport: glucose, AA, lipids
  • Impaired endocrine functions: IGF2, leptin, CRH (reduced IGF2 – reduced fetal size)
  • Dysregulated placental barrier: increased passage of glucocorticoids – impaired organ development and increased risk of disease
32
Q

How are IGF-2 levels different in male and female placentas and why is this?

A

IGF-2 in the placenta upregulated in males but not in females - placenta of male foetuses prioritise making fetus large and female placentas prioritise the limitation of later disease development

33
Q

Which sex is more likely to up regulate glucocorticoid barrier?

A

Females

34
Q

How does alcohol affect foetal development?

A

Upregulates glucocorticoid expression

35
Q

How does hypoxia affect placenta in females?

A

Hypoxia reduces Hsd11b2 expression – female glucocorticoid barrier is impaired

CARDIO TEST 3 (10 decks)

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