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Reproduction > 3.1 Pregnancy and Placentation Pt 2. Function > Flashcards

3.1 Pregnancy and Placentation Pt 2. Function Flashcards

1
Q

Functions of the placenta:

A
  • exchange of nutrients
  • changes the metabolism of the mother
  • protection from trauma and teratogens
  • immunological protection
  • hormone section
  • influence development vital organs
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2
Q

Exchange of nutrients and waste:

A

the ​intimate association between the fetal placenta and maternal tissues - allows for exchange of nutrients and waste

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3
Q

2 ways molecule cross the fetus:

A
  1. Histotrophic
  2. Haemotrophic
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4
Q

Histitrophic:

A

uterine secretions - maternal milk or juices

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5
Q

heterotrophic:

A

direct transfer between fetal and maternal bloodstream by the ​definitive placenta

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6
Q

Histotrophic transfer to fetu​s is supplied by?

A

uterine secretions

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7
Q

histotrophic transfer is rich in?`

A

-glycoproteins
- growth factors
- micronutrients

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8
Q

When can histotrophic transfer be used?

A
  • pre
  • peri (during)
  • early post implantaion
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9
Q

Histotrophic: trophoblast either __ or __ material?

A

absorb material or engulf material via phagocytosis

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10
Q

histotrohphic: pinocytosis

A

pinocytosis persists in later pregnancy
- in pig, horse, carnivore via areolea and

  • sheep/carnivores via endometrial glands and haemophagous zones (areas of RBC update for FE)
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11
Q

Haematrophic nutrition:

A

-rapid growth phase after organogenesis​
- 2 discrete circulations close enough to permit rapid and efficient materials between bloodstreams
- # of transfer routes utilized varying based on the molecule structure

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12
Q

Factors that can affect nutrient exchange:

A
  • specific transport mechanism for individual nutrients
  • vasular dynamics
  • placenta utilization
  • surface area
  • concentration gradient
  • some molecules impacted by placental barrier thickness
  • others blood flow (ex: oxygen)
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13
Q

Simple diffusion:

A
  • very small molecular weight molecules, or very lipid soluble species
  • Na+, K+ , Cl- can pass through (although probably active transport)
  • FA, Cholesterol, fat (limited across) , water (with ease), soluble vitamins, non-conjugated​ steroids
  • water, urea, uric acid, creatinine gases
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14
Q

simple diffusion: where is concentration higher?

A

where molecule is produced

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15
Q

Facilitated diffusion:

A
  • for less soluble​ molecule often needed in large amounts ex: glucose
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16
Q

Main source of of energy for fetus?

A

glucose

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17
Q

Facilitated​ diffusion: Glucose requires?

A

-Higher mother-to-fetus​ gradient
uses transporters
- levels in fetus reflect that of mother

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18
Q

Faciliated diffusion: 1/3 of glucose is used by?

A

placenta - most ending up as lactate, lactate then used by fetus

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19
Q

Active transport:

A
  • All other molecules which are potentially​ toxic: Fe2+, I-, CA2+, Phosphate
  • lipid soluble: AA, water, soluble vitamins
  • Large proteins like IgG: humans (3 layers)&raquo_space; carnivores (4 layers)&raquo_space;ungulates (binding proteins
    -limited transfer of macromolecule

**Concentration can be higher on either side so against a concentration gradient
*Process requires energy

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20
Q

active transport is needed to maintain which gradients?

A

Na+, K+, Cl-

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21
Q

active transport: iron uptake

A

Uptake of transferrin in humans & rodents via transferrin receptors
- Progesterone-dependent​ secretion of uteroferrin in mare
- Carnivores seppage of maternal RBCs taken up by trophoblast- heme sourced from RBC

22
Q

Oxygen diffusion

A
  • embryo erythrocytes (nucleated and fetal erythrocytes (nucleated from the liver) then alter spleen and bone marrow - globin change different from adult
  • oxygen diffuses freely across the placenta and rapidly reaches equilibrium between maternal and fetal hemoglobin​
23
Q

oxygen diffusion: fetal haemoglobin

A

fetal haemoglobin has a higher affinity and fetal blood contains​ more haemoglobin

24
Q

oxygen diffusion: fetus-to-mother loss of CO2:

A

enhances O2 transfer and mother to fetus​ loss of O2 increases maternal affinity for O2 and reduces affinity for CO2

25
Q

fetal oxygentaion​ is regulated by?

A

how much oxygen​ they need

26
Q

2 protective functions:

A
  1. physical
  2. teratogens
27
Q

physical​ protection:

A

the fetal membranes, especially the amnion and associated fluid-cushion

28
Q

tetratogens: protection:

A

teratogens are external influences that induce developmental abnormalities in the fetus - can be toxins or pathogens

29
Q

Teratogens: What can pass?

A
  • microorganisms - especially viruses (cross with ease)
  • radiation​
  • nutritional deficiencies
  • hyperlycaemia
  • chemicals:
30
Q

Placenta/fetus= foreign: Trophoblast express

A

MHC Class I

31
Q

“Paternal alloantigens” =

A

MHC class I alleles that are co-dominantly expressed

32
Q

How is the immune system modulated in pregnancy?

A
  1. specific: directed against paternal alloantigen​
  2. non-specific: general dampering of the immune system
    - increase tregs
    - change in cytokines - decreased IFNg
  3. traditionally we only consideren suppression but changes are more complexed and specific
33
Q

fetal defense mechanism:

A
  • control the immune system
  • trophoblast derived products that modulate the local environment to protect themselves from killinhg
  • fetal producton of IDO: depletes AA tryptophan, inhibits T cells prliferstion
34
Q

Hormone of pregnancy: progesterone

A
  • inhibits follicular development and ovulation (feedback on gonadotrophins)
  • decreases contractility of myometrium (P4 block)
  • stimulates endometrial glands to secrete histotroph
    -immunosupressant
  • mammary gland development ( but not secretion of milk
  • mild catabolic effect
  • binds to one of 2 receptors -PRA and PRB
35
Q

2 sources of progetserone:

A
  • ovary (Corpus luteum)
  • placenta (trophoblast)
36
Q

Progetserone process:

A
37
Q

Progesterone source in dog and sow

A

Corpus luteum only

38
Q

Progesterone source in cow

A

Corpus luteum mostly: contribution by placenta 6-8 months

39
Q

Progesterone source in horse

A

early CL, days 70 -100 placenta

40
Q

Progesterone source in cat

A

mostly CL then 50 day placenta (63 total)

41
Q

Progesterone source in sheep

A

early CL, 55 days placenta

42
Q

Progesterone source in human

A

early CL, 40 day placenta

43
Q

estrogen function:

A
  • growth of myometrium (P4)
  • Proliferation of endometriun
  • stimulates uterine blood flow
44
Q

estrogen sources:

A
45
Q

When does estogen generally peak?

A

late pregnancy

46
Q

estorgen source: horse

A

early ovarianfollicles the late fetal gonads and placenta

47
Q

estrogen: cow and sheep

A

placenta (+ovary)

48
Q

estrogen source : pig

A

placenta

49
Q

where does the fetus conjugate all steroids?

A

mainly in fetal liver but also adrenals

50
Q

placental gonadotrophins: mare

A

eCG

Reproduction (15 decks)

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