placental function

Question 1

when and what does placenta take over?

Answer 1

by 11th week. the placenta, in particular the syncytiotrophoblast, takes over production of estrogen and progesterone from the corpus luteum

Question 2

where does placental circulation begin?

Answer 2

at maternal arteries

Question 3

how many maternal arteries are there? how are their shape and function?

Answer 3

100

spiral and exhibit high blood pressure

Question 4

where do maternal arteries led into? How does blood flow?

Answer 4

the intervillous spaces within the cotyledon. blood shoots out the open ends of the spiral arteries to fill the intervillous spaces, and returns via the open-ended maternal decidual veins.

Question 5

how much blood does a fully mature placenta hold? how often is it circulated?

Answer 5

150cc of blood within the intervillous spaces. it is recirculated about four times per minute.

Question 6

what surface is used for exchange of gases? how much room is there?

Answer 6

villous branching within the placenta. provides up to 10-11 square meters of surface area for exchange.

Question 7

how does mother provide fetus passive immunity?

Answer 7

maternal antibodies pass through placenta and provides immunity for several months after birth.

Question 8

how is it that the maternal immune system does not respond to the fetal portion of the placenta?

Answer 8

the fetal component does not express major histocompatibility complex molecules. It is therefore not recognized by immune system.