Repo 8: Pregnancy Flashcards
What happens to the yolk sac as the foetus grows?
Yolk sac disappears as the amniotic sac enlarges due to growth of the foetus
So chorionic sac is occupied by the expanding amniotic sac
What is meant by the term haemomonochorial?
That only one single trophoblast layer separates maternal blood from foetal capillary blood
The two circulations never mix!
What are chorionic villi?
Finger like projections that the Charon forms
They represent the point of exchange between the maternal and foetal circulations
What is an ectopic pregnancy?
Implantation at a site other the the uterine body, often in the Fallopian tube
What is placenta praevia?
Implantation int eh lower uterine segment that can cause haemorrhage in pregnancy
Requires a c-section as the birth canal is obstructed
Which cells in the endometrium prepare for implantation?
Pre-decidual cells
How must the flow and resistance of the blood supply in the endometrium adapt for pregnancy?
Spiral artery remodelling
To create a high flow and low resistance blood supply
(This does not happen in pre-eclampsia)
Which layer of trophoblast impedes the mother?
Cytotrophoblast (lined with syncytiotrophoblast)
How does the barrier of the placenta change over the course of pregnancy?
Barrier is thick in first trimester (OK as demands of foetus are fairly low)
As placenta matures to meet increasing foetal demands, is decreased the interhaemal distance by thinning the trophoblast layers (now just syncytiotrophoblast) and increasing the SA for exchange through branching of the villus tree
Which vessels carry oxygenated and deoxygenated blood to the foetus?
2 umbilical arteries carry deoxygenated blood from foetus to placenta
1 umbilical vein carries oxygenated blood from placenta to foetus
What is the function of hCG?
Produced in first 2 months of pregnancy to support CL
Excreted in maternal urine (used for pregnancy testing)
Which trophoblast layer secretes hCG?
Syncytiotrophoblast
Which steroid hormones does the placenta produce?
Progesterone and oestrogen
Responsible for maintaining pregnancy state (progesterone increases maternal appetite to lay down fats for late pregnancy)
Placenta takes over CL production by 11th week
What is the main function of hPL?
Increases glucose availability to foetus
Give an example of molecules that are transported across the placenta by simple diffusion, facilitated diffusion, active transport, and receptor mediated transport.
Simple diffusion: water, urea, electrolytes, gases
Facilitated diffusion: glucose
Active transport: AAs, iron, vitamins
Receptor mediated transport: IgG