Implantation, the placenta and hormonal changes in pregnancy Flashcards
What are trophoblasts?
These are cells of the blastocyst that invade the endometrium and myometrium
What do trophoblasts secrete?
Secrete betaHCG
What is chorion?
Is that which becomes the placenta
What is the amnion?
It is the layer that becomes the amniotic sac
What happens to trophoblasts?
- Differentiation of trophoblasts
- Trophoblastic invasion of decidua and myometrium
- Remodelling of the maternal vasculature in the utero-placental circulation
- Development of vasculature within the trophoblast
What days are the window of implantation?
Days 5-6 is the window of implantation
Where does betaHCG come from and what does it recognise?
betaHCG comes from placental tissue and is the maternal recognition of pregnancy
What does betaHCG allow the maintenance of and what does it lead to?
betaHCG allows the maintenance of the corpus luteum leading to progesterone production
What does decidualization occur under?
Decidualization occurs under progesterone
Up until what point is production of progesterone by corpus luteum vital?
Production of progesterone by corpus luteum is vital until placental steroidogenesis is established
What is betaHCG the basis of?
Basis of urinary pregnancy test
When are betaHCG levels maximal by?
Levels maximal by 9-11 weeks
What is serum betaHCG useful for monitoring?
Serum betaHCG useful for monitoring early pregnancy complications like ectopic pregnancy or miscarriage
What are the functions of the placenta?
- Steroidogenesis
- Oestrogen
- HPL
- Progesterone
- Cortisol - Provision of maternal O2, CHO, fats, amino acids, vitamins, minerals, antibodies
- Removal of CO2, urea, NH4 and minerals
- Barrier against bacteria, viruses, drugs
Why is the placenta good at its job?
- Has huge maternal uterine blood supply at low pressure
- Has a huge reserve in function
- Has a huge surface area in contact with maternal blood
