Implantation and placentation

Question 1

Trophoblast will become

Answer 1

(inner cytotrophoblast and outer syncytiotrophoblast whose fingers inade the endometrium)

the placenta

Question 2

Inner cell mass will become

Answer 2

embryo

Question 3

where are the chorionic villi

Answer 3

from the umbilical arteries (from foetus) and veins (to foetus) in the chorion branches into the placenta

Question 4

4 general functions of placenta (organs)

Answer 4

• supplies nutrients (gut)
• exchanges O2 and CO2 (lung)
• regulates fluid volume and disposes of waste metabolites (kidney)
• synthesises steroids and proteins (endocrine gland)

Question 5

how does glucose/amino acids/lipids pass through placenta

Answer 5

via facilitated diffusion
via active transport
as free fatty acids

Question 6

human chorionic gonadotropin key function

Answer 6

to prevent involution of corpus luteum (encourages it)

• it causes CL to secrete progesterone and oestrogen for a few months (these prevent menstruation and cause proliferation of endometrium)

Question 7

what effect does human chorionic gonadotropin have on male foetus

Answer 7

stimulates the foetus’ testes to produce testosterone (which stimulates the growth of male sex organ)

Question 8

function of oestrogen in pregnancy

Answer 8

proliferative:
uterus
breasts
female external genitalia

Relax pelvic ligaments (allow easier passage)

Question 9

after the CL, what secretes the oestrogen?

Answer 9

the syncytiotrophoblast cells of the placenta

Question 10

reasons why progesterone is important

Answer 10

TO PROGRESS PREGNANCY

• causes decidual cells to develop in endometrium (these key for nutrition)
• decreases contracility of pregnant uterus (not yet)
• helps involvement in nutrition
• helps oestrogen prepare breasts for lactation