Placenta Structure + Function

Question 1

What are the 2 parts of the placenta?

Answer 1

1. fetal - develops from chorionic sac = villous chorion
2. maternal - derived from endometrium = decidua basalis

Question 2

What are the functions of the placenta?

Answer 2

PNREH

• Protection
• Nourishment
• Respiration
• Excretion
• Hormone Production

Question 3

What are the 3 parts of the decidua?

Answer 3

1. Basalis - lies just under embryo and contributes to placenta
2. Capsularis - surrounds embryo
3. Parietalis - surrounds outer layer on other side of uterine cavity from capsularis

Question 4

What is the decidual reaction and what causes it?

Answer 4

changes in endometrium induced by progesterone every uterine cycle but especially pronounced in implantation

• stromal cells swell via accumulation of glycogen etc.

Question 5

How does placental circulation look?

Answer 5

Question 6

What happens to the chorionic villi as the placenta develops?

Answer 6

• **smooth chorion - **under decidua capsularis, they degenerate
• villous chorion - under basalis, they proliferate

Question 7

What is the layer just between the intervillous space and decidua basalis?

Answer 7

cytotrophoblast shell