Female Reproductive Physiology Flashcards Preview

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Flashcards in Female Reproductive Physiology Deck (39):
1

during sexual differentiation into female, the absence of what 2 hormones causes what important things to happen?

absence of androgens and MIF (mullerian-inhibiting factor) --> Wolffian ducts regress and male genitalia do not form, and the mullerian ducts develop into the female reproductive tract

2

when do FSH and LH peak during a female's life? (2)

2-6 months of post-natal age and before menarche

3

when does the number of oogonia in the fetal ovary peak?

at 6 months of fetal development

4

what hormones stimulate the production of oogonia in the ovaries?

hCG from the placenta and fetal FSH and LH

5

what is the function of aromatase?

converts testosterone to estrone or estradiol, the primary secretory products of the ovary

6

how is estriol made?

estrone or estradiol is converted to estriol in the liver

7

which sex hormones are mostly bound to albumin?

estrogen, androstenedione

8

describe the steps of female puberty

GnRH pulses commence at about 9 year of age --> increase in FSH and LH --> restart ovarian follicular development and production of estradiol by steroidogenic tissue --> estrogen leads to growth spurt and secondary sex characteristics

9

what hormone induces closure of growth plates in long bones in girls?

estrogen

10

what happens when pregnancy does not happen at the end of the menstrual cycle?

the corpus luteum dies and progesterone and estrogen decrease (because hCG is not released by a trophoblast) --> FSH increases due to loss of negative feedback

11

what hormone induces maturation of follicles during the menstrual cycle?

FSH

12

what happens when a dominant follicle forms during the menstrual cycle?

it begins to secrete estrogen autonomously --> FSH is decreased via negative feedback --> atresia of non-dominant follicles

13

what happens when estrogen peaks during the menstrual cycle?

it induces a switch in the hypothalamic-pituitary unit from negative to positive feedback so that estrogen stimulates a surge in LH --> ovulation and formation of corpus luteum

14

what does the corpus luteum do once it forms?

produces enormous amounts of progesterone --> inhibits LH and FSH secretion

15

role of inhibin

produced by the ovary and selectively inhibits FSH release --> FSH surge not as large as LH surge

16

role of theca cells in ovary

under the control of LH, produce androgens that diffuse into granulosa cells

17

role of granulosa cells in ovary

FSH stimulates granulosa cells to stimulate aromatase activity, which converts androgens (from theca cells) to estrogens

18

what hormone predominates during the luteal phase of the menstrual cycle?

progesterone

19

what hormone predominates during the follicular phase of the menstrual cycle?

estrogen

20

which phase of the menstrual cycle does the proliferative phase occur in? what happens during the proliferative phase?

follicular phase; growth of myometrium stimulated by estrogens

21

which phase of the menstrual cycle does the secretory phase occur in? why?

luteal phase due to progesterone from the corpus luteum

22

what leads to menstrual bleed?

uterine spiral artery vasoconstriction is signaled by the decline of progesterone at the end of the luteal phase --> sloughing of myometrium

23

implantation within the wall of the uterus occurs __ days after _____

6; fertilization

24

pregnancy: ______ secrete hCG, which is detectable in blood _____ after conception and on home test in urine _____ after conception

syncytiotrophoblasts (of placenta); 1 week; 2 weeks

25

blastocyst enters uterine cavity __ days after _____

5; LH peak

26

what hormone rescues the corpus luteum and how?

hCG maintains corpus luteum (and thus progesterone) for first 8-10 weeks of pregnancy by acting like LH (otherwise no luteal cell stimulation --> abortion)

27

why do menstrual cycles stop during pregnancy?

hCG stimulates estrogen and progesterone release from the corpus luteum which inhibits gonadotropic secretion preventing menstrual cycles during pregnancy and stimulates continued growth of the endometrium to nurture the growing implanted embryo and fetus

28

what enzyme converts cholesterol to pregnenolone?

cholesterol desmolase

29

what enzyme converts pregnenolone to progesterone?

3beta-hydroxysteroid dehydrogenase

30

which enzyme is plentiful in the placenta and what is its function?

aromatase; converts androgen to estrogen

31

what can be measured in maternal blood as index of fetal distress?

estriol

32

when does hCG peak and why does it wane during pregnancy?

first trimester of pregnancy; because placenta is responsiblef or most of the estrogen and progesterone in 2nd and 3rd trimesters and corpus luteum is no longer necessary

33

hCG has homology with what other hormones? in what subunit?

LH, FSH, TSH; alpha

34

functions of oxytocin (2)

1. promotes uterine contractions
2. assists in milk let-down

35

how does lactation start, and what is needed to maintain it?

after labor, the decrease in progesterone and estrogen disinhibits lactation; suckling causes nerve stimulation and oxytocin and prolactin production

36

how does prolactin inhibit ovulation in females? what does the same mechanism do in males?

prolactin inhibits GnRH synthesis and release; inhibits spermatogenesis in males

37

why does estrogen production decrease in menopause?

age-linked decline in ability of ovaries to produce mature follicles

38

hormonal changes of menopause (3)

decreased estrogen, large increase in gonadotropins (FSH > LH) due to loss of negative feedback via estrogen, increased GnRH

39

how do reproductive events/disorders cause osteoporosis?

loss of gonadal steroids removes the anti-resorptive effects of these hormones --> loss of bone mineral that leads to osteopenia/osteoporosis