Development and Function of the Placenta Flashcards
True or false: early placental development takes place in a hypoxic environment (why?)
- True
- Trophoblast invades uterus, including spiral arterioles, which blocks off maternal blood flow in the early stages
By which trimester are chorionic villi containing fetal capillaries bathed in maternal blood?
Second
What happens to placental weight over the course of a pregnancy?
- Logarithmic shaped curve
- Starts growing faster, but growth slows over time
What are links between placental function and the weight/survival of the resultant child?
- Placental weight is correlated w/ foetal weight. Low placental weight associated with poor fetal growth
- Low placental weight associated with increased risk of stillbirth
Greg has diabetes and CVD. w/ respect to the placenta, why might it not be his fault?
Low placental weight is associated with increased risk of cardiovascular disease and insulin sensitivity.
True or false: the higher the fetus : placenta weight ratio, the better.
- False
- While many negative outcomes can arise from low fetal birthweight and high placental weight, there is an optimal setpoint somewhere
Is the uterus an immune protected site? After all, the baby contains 50% of the father’s genome (non-self)
No. Women can produce adaptive/innate immune responses to STIs during/in the absence of pregnancy
True or false: mothers are at a greatly increased risk of infection due to immunosuppresion in pregnancy
- False
- Immune response is decreased, but not to that extent
Which 2 types of cells allow the body to generate immune tolerance against the father’s antigens in the fetus?
- T Reg (police officer)
- Th2 (2 people -> immune response needs help to understand)
When does the female body learn to tolerate male antigen in the case of pregnancy
- Straight away; as soon as ejaculation occurs, inflammatory response kicks off,
- APCs present antigen at lymph nodes, and T reg/Th2 cells are educated
With reference to normal placental development, how does a weak immune system affect placental development?
- Normally, trophoblast cells replace endothelium on the inner lining of the spiral arteries
- In the absence of enough Treg cells, this remodelling is impaired, and so no transient hypoxia (increased risk of placental remodelling/preeclampsia etc)
What are the key functions of the placenta?
- Deliver oxygen/remove waste from fetus
- Provide nutrients (glucose micronutrients)
- Excretion functions as kidney to balance bicarboante, lactic acid, H+, ura/creatinine etc.)
- Immunity (antibodies are transferred to baby)
- Endocrine: hCG (maintin luteum), oestrogen (makes tissue soft/supple), progesterone (maintain endometrium well perfused)
Describe the fundamental mechanics of placental gas exchange
- HbF has higher affinity for O2 than HbA, so it pulls aoxygen across the placental membrane
- CO2 can just diffuse across the placental membrane
Describe the development of the placenta
- Trophoblast invades decidua, becomes “chorion”
- Spiral arteries eventually spill out into the intervillous space
- Villi (fingers) of chorionic tissue are filled with fetal blood vessels
- Two placental arteries carry deoxygenated blood to the placenta, and one vein carries oxygenated blood away
(Think of a child called AVA)
