Pregnancy

Question 1

2 roles of placenta

Answer 1

• interface between maternal and fetal plasma
• protects fetus from attack by the maternal immune system

Question 2

what 5 main hormones produced in placenta

Answer 2

Protein:
- human chorionic gonadotrophin (hCG)
- human placental lactogen (hPL)
- placental growth hormone (pGH)

Steroid:
- progesterone
- estrogens

Question 3

what is hcg structually related to

Answer 3

LH

Question 4

hCG production: 2 cell model?

Answer 4

cytotrophoblast produces GnRH
GnRH stimulates syncytiotrophoblast
which then produces hCG

Question 5

what is role of hCG

Answer 5

signals pregnancy to maternal organism
- rescues corpus luteum!
- maintains progesterone production by placenta

used in pregnancy test
and a marker of foetal wellbeing (if too high then indicates more than one foetus)

Question 6

where is progesterone produced

Answer 6

syncitiotrophoblasts
after 9th week (and so corpus luteum not needed after this point)

Question 7

where does placenta get cholesterol to make the progesterone

Answer 7

mum

Question 8

what is progesterone release regulated by

Answer 8

hCG

Question 9

roles of progesterone

Answer 9

• maintains lining of uterus
• decreases prostaglandin = relaxes myometrium
• supresses t lymphocyte tissue rejection (immunological provelage)
• effects of peripheral smooth muscle

Question 10

which estrogens are produced in placenta

Answer 10

all 3
estradiol
estriol
and estrone

Question 11

which estrogen is made only via fetus

Answer 11

estriol
its precursor is made in fetal liver

Question 12

why is estriol only made in week 9

Answer 12

This bit only happens from week 9 = 9 this is when maturation of steroid synthesis pathway occurs

Question 13

role of estrogens in preganncy

Answer 13

• vasodilation and good uteroplacental blood flow
• regulates progesterone production in 3 trimester
• and mammary gland devleopment

Question 14

how do we know pituitary growth hormone not needed for fetal growth

Answer 14

anencephalic fetuses and women with GHD both have normal growth

so only placental growth hormone affects it

Question 15

how does pGH influence fetal growth

Answer 15

influences IGF-I production by maternal liver
which effects maternal metabolism
increase nutrients avialable for transport across placenta for foetus

• via gluconeogensis and lipolysis

Question 16

effects of hPL

Answer 16

possible lactogenic activity
- regulates maternal metabolism via IGF-I
- and stimulates onset of maternal behaviour via neurogenesis

Question 17

4 phases of preg

Answer 17

phase 0 = quiescence
phase 1 = activation
phase 2 = stimulation
phase 3 = involution

Question 18

what inhibits activation thus keep pregnancy in phase 0

Answer 18

progesterone
and possbile hPL

Question 19

what are the 3 activators

Answer 19

estrogen
prostaglandins
oxytocin

Question 20

what are the contraction associated proteins

Answer 20

• prostaglandin and oxytocin receptors
• connexins

Question 21

what does involution do

Answer 21

• Sustained contractions of uterus = contsricts arteries to prevent blood loss
  Reduces enlarged uterus back to pre pregnancy state

Question 22

possible triggers of partruition

Answer 22

• functional progesterone withdrawal (less potent receptor produced)
• increase in estrogens via increased fetal androgens
• placental CRH! (when activated early = preterm birth)

Question 23

what happens once partruition is initiated

Answer 23

• increased prostaglandin synthesis
• increased oxytocin receptors

Question 24

what age do milk ducts appear

Answer 24

at 4 weeks gestation in the baby

Question 25

what stimulates growth of milk duct first

Answer 25

puberty = estrogen, growth hormone and adrenal steroids

Question 26

during preganncy, what hormones cause increase in lobulo-alveolar growth

Answer 26

estrogen
progesterone
prolactin
possible hPL

Question 27

what is milk production regulated by

Answer 27

prolactin from APG
(high all thoguhout pregnancy)
but
its actions are surpessed by high ateroid and hPL levels = dont lactate until after birth

Question 28

what action maintains prolactin levels after birth and how

Answer 28

suckling
activates neural pathways that surpess dopamine
which is a negative regulator of prolactin

Question 29

what is milk ejection stimulated by

Answer 29

oxytocin from APG

Question 30

3 hromones that have slightly diff function in fetus than adult

Answer 30

• thyroid hromones
• adrenal hromones
• growht hormones

Question 31

why is T3 low in fetus

Answer 31

low type 1 deiodinase
and
high type 3 deiodinase

Question 32

what is thyroid hormone important for in baby

Answer 32

brain development
e.g. myelination, neurogenesis, neuronal and glial cell differentiation

Question 33

what happens at birth with thyroid hormones

Answer 33

TSH, T3 and T4 rise rapidly

Question 34

how is the adrenal coretex diff in fetus

Answer 34

the fetal zone of the crtex takes up most of the glands

Question 35

what does fetal zone of cortex produce

Answer 35

DHEAs
which are converted to estriol in placenta

Question 36

what does medulla in fetus release

Answer 36

adrenaline

Question 37

function of adrenaline in neonate

Answer 37

not fully known but
- thermogenesis
- releasing surfactant to allow lung expansion
- blood pressure regulation

Question 38

what is growth in fetus controlled by

Answer 38

• genetic factors
• placental nutrient uptake
• placental growth horomone
• insulin like growth factors (important cuz seen in knockout experiments)