Endocrine Day 3- Pregnancy and Male reprod. Flashcards Preview

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Flashcards in Endocrine Day 3- Pregnancy and Male reprod. Deck (50)
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1

What happens to corpus luteum at end of menstural cycle in the absence of pregnancy?

CL degenerates and its produciton of progesterone and estraidol falls

2

What does the placenta produce during the beginning of preganncy?

HCG (human chorionic gonadotropin)

  • This "rescues" the CL by acting on LH receptors on CL
  • HCG has same beta subunit to LH and will act on LH receptors on CL
  • CL will continue to produce progesterone until HCG levels fall at 9-12 weeks

3

Progesterone ____ pregnancy

maintains

4

Why does E/P continue to increase after HCG decreases?

  • Placenta starts to make own E/P
    • placenta makes estriol (major estrogen of pregnancy)
  • Progesterone dominant until end of pregnancy

5

HCG levels are maintained until what week? Why?

  • HCG levels maintained until week 9-12
  • once placenta starts making own E/P, then HCG starts to fall
  • Corpus luteum is then no longer maintained

6

What is the main estrogen of pregnancy?

Estriol

7

What is main estrogen of ovaries?

17-beta-estradiol

8

What is main estrogen of fat tissue?

Estrone

9

What is HCG?

  • Secreted by trophoblast 7-9 days after ovulation
  • responsible for maternal recognition of pregnancy
  • same structure and function as LH
  • Maintains CL
  • Promotes estrogen and progesterone secretion from CL (CL is important in first 3 months)
  • Stimulates testosterone production by the testes of male fetus

10

What triggers delivery process?

  • Placental CRH stimulates fetal production of ACTH--> DHEA-S produced by fetus--> placenta where aromatase enzyme causes increase in local estrogen/progesterone ratio
  • Increase in local prostaglandin (PGF-2 alpha)
  • Increase in maternal oxytocin
  • increase in maternal catecholamines

11

What stimulates secretion of labor hormones?

  • Stretch receptors in cervix progject infor to anoxal projections in spinal cord
  • cause increase in oxytocin from post pituitary
  • increases prostaglandins from uterine wall
  • causing increase in uterine contractions

oxytocin is major player in uterin contractions

12

What stimulates synthesis of breast milk?

Prolactin

13

What stimulates milk ejection?

Oxytocin

14

What acts on pre-pubertal femals breast to increase duct growth?

  • Estrogen
  • GH
  • Adrenal steroids

15

What causes mammary gland development during pregnancy?

  • Estrogen
    • also acting on ant pituitary lactotrophs to increase enlargement/proliferation in preparation for breast feeding
    • BUT high estrogen and progesterone block breast milk synthesis
  • Progesterone
    • development of lobule-alveolar system
  • prolactin
  • GH
  • adrenal steroids

16

What allows milk secretion?

  • Once E/P levels diminish after delivery of placenta, then prolactin levels are allowed to increase and breast milk can be made

17

E and P ____ milk production

inhibit

18

____ causes growth of ductile system in breasts

____ causes development of lobular-alveolar system

 

Estrogen; progesterone

19

What is the funcitonal unit of the milk duct?

Alveoli

20

____ provides tonic inhibition of output of prolactin

dopamine

21

T/F, estrogen increases number and size of lactotrophs

true

also makes them more responsive to stimulatory factors

22

What does suckling of breast cause hormonally?

  • Suckling of breast causes inhibition of dopamine from hypothalamus
  • inhibiton of dopamine cause increase in prolactin levels to increase milk production

23

What hormonal effects does increased prolatin levels have?

  • Increased PRL causes signal to increase dopamine (negative feedback to decrease further PRL output)
  • Signals dopamine neurons to inhibit LHRH secretion
    • this lowers LH/FSH/E/P and causes amenorrhea and state of infertility
  • GnRH (LHRH) receive dopaminergic input from dopamein
    • when dopamine active, inhibits LHRH, gonadotropin, E/P all in arcuate nucleus

24

What is relative response of prolactin levels initially after birth versus months out?

  • Immediately after placenta birthed, prolactin levels allowed to increase and will increase rapidly with suckling episode
  • Months later, level of PRL released with suckling decreases
    • this allows LHRH neurons to escape dopamine inhibition and fertility is restored

25

Lenght of release of prolactin after birht is a ____ phenomenon

cultural

26

What is sheehan's syndrome?

  • Panhypopituitarism caused by major blood loss during birth
    • major blood loss decreases flow to the ant pituitary
  • Causes
    • failure to lactate because of degnerated lactorophs
    • loss of coritcotrops for ACTH, causes absence of pubic/axillary hair
    • patient is amenorrheic d/t decrease LH/FSH
    • Hypothyroidism
  • Treatment
    • admin end organ hormone (TH, E, P, coritcosteroids)

27

What does inhibin inhibit?

FSH

28

The male reproductive tract is  a ____ feedback system only

negative

29

What is target of LH in the male?

Leydig cells

30

What do leydig cells produce?

Testosterone and some estradiol (both long loop negative feedback to hypothalamus and pit)