3.1 Pregnancy and Placentation Pt 2. Function

Question 1

Functions of the placenta:

Answer 1

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

Question 2

Exchange of nutrients and waste:

Answer 2

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

Question 3

2 ways molecule cross the fetus:

Answer 3

1. Histotrophic
2. Haemotrophic

Question 4

Histitrophic:

Answer 4

uterine secretions - maternal milk or juices

Question 5

heterotrophic:

Answer 5

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

Question 6

Histotrophic transfer to fetu​s is supplied by?

Answer 6

uterine secretions

Question 7

histotrophic transfer is rich in?`

Answer 7

-glycoproteins
- growth factors
- micronutrients

Question 8

When can histotrophic transfer be used?

Answer 8

• pre
• peri (during)
• early post implantaion

Question 9

Histotrophic: trophoblast either __ or __ material?

Answer 9

absorb material or engulf material via phagocytosis

Question 10

histotrohphic: pinocytosis

Answer 10

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)

Question 11

Haematrophic nutrition:

Answer 11

-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

Question 12

Factors that can affect nutrient exchange:

Answer 12

• 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)

Question 13

Simple diffusion:

Answer 13

• 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

Question 14

simple diffusion: where is concentration higher?

Answer 14

where molecule is produced

Question 15

Facilitated diffusion:

Answer 15

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

Question 16

Main source of of energy for fetus?

Answer 16

glucose

Question 17

Facilitated​ diffusion: Glucose requires?

Answer 17

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

Question 18

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

Answer 18

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

Question 19

Active transport:

Answer 19

• 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

Question 20

active transport is needed to maintain which gradients?

Answer 20

Na+, K+, Cl-

Question 21

active transport: iron uptake

Answer 21

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

Question 22

Oxygen diffusion

Answer 22

• 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​

Question 23

oxygen diffusion: fetal haemoglobin

Answer 23

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

Question 24

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

Answer 24

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

Question 25

fetal oxygentaion​ is regulated by?

Answer 25

how much oxygen​ they need

Question 26

2 protective functions:

Answer 26

1. physical 2. teratogens

Question 27

physical​ protection:

Answer 27

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

Question 28

tetratogens: protection:

Answer 28

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

Question 29

Teratogens: What can pass?

Answer 29

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

Question 30

Placenta/fetus= foreign: Trophoblast express

Answer 30

MHC Class I

Question 31

“Paternal alloantigens” =

Answer 31

MHC class I alleles that are co-dominantly expressed

Question 32

How is the immune system modulated in pregnancy?

Answer 32

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

Question 33

fetal defense mechanism:

Answer 33

- 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

Question 34

Hormone of pregnancy: progesterone

Answer 34

- 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

Question 35

2 sources of progetserone:

Answer 35

- ovary (Corpus luteum) - placenta (trophoblast)

Question 36

Progetserone process:

Answer 36

Question 37

Progesterone source in dog and sow

Answer 37

Corpus luteum only

Question 38

Progesterone source in cow

Answer 38

Corpus luteum mostly: contribution by placenta 6-8 months

Question 39

Progesterone source in horse

Answer 39

early CL, days 70 -100 placenta

Question 40

Progesterone source in cat

Answer 40

mostly CL then 50 day placenta (63 total)

Question 41

Progesterone source in sheep

Answer 41

early CL, 55 days placenta

Question 42

Progesterone source in human

Answer 42

early CL, 40 day placenta

Question 43

estrogen function:

Answer 43

- growth of myometrium (P4) - Proliferation of endometriun - stimulates uterine blood flow

Question 44

estrogen sources:

Answer 44

Follicles, CL, placenta, fetal gonads -

Question 45

When does estogen generally peak?

Answer 45

late pregnancy

Question 46

estorgen source: horse

Answer 46

early ovarianfollicles the late fetal gonads and placenta

Question 47

estrogen: cow and sheep

Answer 47

placenta (+ovary)

Question 48

estrogen source : pig

Answer 48

placenta

Question 49

where does the fetus conjugate all steroids?

Answer 49

mainly in fetal liver but also adrenals

Question 50

placental gonadotrophins: mare

Answer 50

eCG