Reproduction 3: Female Repro/Menstrual Cycle Flashcards Preview

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Flashcards in Reproduction 3: Female Repro/Menstrual Cycle Deck (134):
1

What is the fundamental reproductive unit of the female repro system?

Gonad = ovary, follicle is the primary reproductive unit

2

What is included in the female reproductive system?

oviducts, uterus, cervix, vagina, external genitalia

3

What is the internal genitalia derived from

mullerian ducts

4

GnRH is activated at puberty. What activates it?

Kisspeptin

5

What promotes secondary sex characteristics?

increased GnRH pulsatility during REM sleep

6

What stimulates pulsatile release of gonadotropins?

GnRH

7

What is the differential levels of GnRH at different stages of life?

spikes in fetal and infant development

low during childhood

elevated at night during puberty

elevated spikes during reproductive years

constantly high in menopause due to lack of neg feedback

8

The menstrual cycle causes physiological changes in what two organs?

ovary and uterus

9

What are the cycles called for the ovary and uterus respectively?

ovary: ovarian cycle
uterus: endometrial cycle

10

What causes the monthly menstrual pattern?

HPG axis feedback

11

Discuss the female HPG Axis

hypothalamus releases GnRH

GnRH stimulates anterior pituitary to release LH and FSH

12

What does FSH target?

Granulosa cells

13

What does LH target?

Theca cells and granulosa cells

14

What do theca cells do?

produce progestins and androgens

15

What do granulosa cells do?

produce progestins, estrogens, inhibins, and activins

converts androgen precursors to estradiol

16

What does FSH do?

stimulates follicular development and conversion of androgen precursors to estradiol

17

What does LH do?

stimulates biosynthesis of estrogens, induces ovulation and luteinization

18

When is LH higher than FSH?

reproductive years

19

What do theca cell do and what kind of receptors do they have?

produce androgens and progestin

receptors for LH

20

What do granulosa cells do and what kind of receptors do they have?

produce estrogens, progestins, inhibins, activins

receptors for LH and FSH

21

What kind of feedback do estrogens have?

negative and positive!

positive important for ovulation

22

What are the three phases of the ovarian cycle?

Follicular phase
Ovulatory phase
Luteal phase

23

What happens in the follicular phase?

Growth of dominant follicle

24

What happens in the ovulatory phase?

Follicle rupture and release of oocyte

25

What happens in the luteal phase?

Formation of corpus luteum

26

What are the three phases of the endometrial (uterine) phase

Menstrual phase
Proliferative phase
Secretory phase

27

What do HPG hormones do?

drive coordinated physiological changes during the menstrual cycle

28

What do physiological changes do?

Signal the hypothalamus

29

When does the proliferative phase occur?

coincident with majority of follicular phase of ovary

30

When does the secretory phase occur?

coincident with luteal phase of ovary

31

What occurs during the menstrual phase?

Endometrial shedding

coincident with early follicular phase of ovary

32

How long is the follicular phase?

variable, 10-14 days

33

How long is the ovulatory phase?

1-3 days

34

How long is the luteal phase?

14 days

35

Describe the stages of a follicle as it passes through the ovarian cycle

primordial follicle -> primary follicle -> secondary follicle -> mature (Graafian) follicle -> (ovulation/follicular rupture) -> corpora lutea -> corpus albicans -> atretic follicle

36

How do the L and R ovaries coordinate?

Alternate between ovaries every month/cycle. If both go through the cycle at the same time you can get dizygotic twins

37

When do the number of primordial follicles peak? How many are left at puberty?

Peak at 20 wks gestation. Only 10% left at puberty

38

What is a follicle?

one oocyte surrounded by a cluster of granulosa cells (germ cell surrounded by endocrine cells)

39

What does the mature ovary do?

maintain and nurture resident oocyte

mature oocyte and release it at the appropriate time

prepare vagina and fallopian tubes for fertilization

prepare the uterine lining to accept and implant a zygote

maintain hormonal support for the fetus until the endometrium is ready to do so

40

In the ovarian cycle, what does day 1 signify?

the first day of menses

41

What is a primordial follicle?

outer layer of pregranulosa cells plus a small oocyte

42

What stage are oocytes arrested in?

diplotene stage of prophase

43

What is a primary follicle?

Larger oocyte surrounded by cuboidal granulosa cells

44

What is required for the follicle to progress from the primordial to primary stage, and where does this happen?

Requires FSH, can happen in utero

45

What happens in a secondary follicle?

differentiation of stromal cells into theca cells

increased number of granulosa cells that become multilayered

enlargement of oocyte

46

What happens in a tertiary follicle, and what else is it called?

Early antral follicle

granulosa cells secrete fluid and create antrum

Granulosa cells closest to oocyte secrete
mucopolysaccharides – forms zona pellucida

47

How long does it take to mature from a primary to a mature graafian follicle?

10-14 days

48

What is the selection of a dominant follicle based on?

sensitivity to FSH and local paracrine actions of AMH produced by granulosa cells

49

What iss a graafian follicle?

the dominant follicle

50

What 3 types do granulosa cells stratify to?

mural cells
cumulus
antral

51

What do mural cells do?

farthest from oocyte
highest number of LH receptors
most metabolically active

52

What are the cumulus cells?

near oocyte, shed at ovulation

53

What are the antral cells?

face antrum, become luteal cells at ovulation

54

The oocyte is still a primary oocyte, arrested in diplotene stage until what occurs?

the LH surge

55

What is a graafian follicle characterized by?

enlargement of the antrum presence of cumulus oophorous

56

What kind of gland is the ovary?

a primary endocrine gland - it has no ducts to convey gametes to the uterus

57

When is FSH high?

at the end of the ovarian cycle

58

What does high FSH do?

recruits new cohort of follicles to enter the follicular phase

59

What do recruited follicles produce, and what does it do?

produce inhibin B, which has a negative feedback on FSH

60

What is important about low FSH?

only the follicle that is most sensitive to FSH will survive

61

What happens when there is more LH than FSH?

stimulates steroid generation by theca cells

62

How does inhibin B influence theca cells?

has a positive paracrine effect to augment steroidogenesis

63

When does increased GnRH stimulate high levels of FSH and LH release from the anterior pituitary?

mid cycle - ovulation

64

What activity does estrogen have on the pituitary during the follicular phase?

negative

65

What feedback does estrogen have on the pituitary during ovulation/

(strong) positive

66

what feedback does estrogen have on the pituitary during the luteal phase?

negative

67

what activity does progesterone have during the luteal phase?

inhibits the pulse generator

68

what do growing follicles produce?

increasing amounts of estrogen

69

What effect does E2 feedback have on the anterior pituitary during the follicular phase?

favors LH over FSH (high frequency, low amplitude pulses)

70

What receptors do theca cells have, and what do they produce?

LH --> synthesize androgens

71

What kind of receptors do granulosa cells have?

LH and FSH

72

What does FSH do in granulosa cells?

increases number of receptors for LH (responsible for LH surge)

increases aromatase (Cyp19) expression --> converts androgens to E2

73

What is the two compartment theory of E2 synthesis?

Thecal cells produce androstenedione from cholesterol, which is transported to granulosa cells nd converted to E2

74

What are the two main events during the ovulatory phase?

LH surge and ovulation

75

What happens during the LH surge?

switch from negative to positive feedback

Follicle continues to mature

oocyte completes meiosis I and begins meiosis II

76

Where is the secondary oocyte arrested during the ovulatory phase, and what allows it to progress?

metaphase II - meosis will complete upon fertilization

77

What happens during ovulation?

expulsion of oocyte-cumulus complex out of ovary

increased inflammatory cytokines

breakdown of ovarian wall

78

What is the positive feedback during ovulation?

increased E2 leads to increased LH, which leads to more E2, etc.

79

What does increased E2 do?

E2 increases progesterone receptors

80

What will cause a decrease in E2 and break the cycle?

rupture of the follicle

81

what will decrease as a result of lower E2?

LH

82

What are the three steps of follicle maturation?

cumulus cell expansion: forms corona radiata and cumulus oophorus

detachment of oocyte-cumulus complex - free floating in antrum

follicle forms bulge against ovarian wall (stigma)

83

what is an oocyte that has completed meiosis I and is arrested in meiosis II?

a secondary oocyte + a polar body

84

What is ovulation?

rupture of ovarian wall and extrusion of cumulus-oocyte complex

85

What occurs after extrusion of the cumulus-oocyte complex?

differentiation of mural granulosa cells into large luteal cells and theca cells into small luteal cells

86

What is the corpus luteum?

remnant follicle

87

What is the major hormone product during the luteal phase?

progesterone, lesser amounts of E2

88

during the luteal phase, what does the follicle no longer produce, and what is the effect?

follicle no longer produces inhibin B, and thus less negative feedback on FSH

89

What inhibin predominates during the luteal phase, and what produces it?

Inhibin A (does not inhibit FSH), produced by the corpus luteum

90

What are the hormonal effects on the HPG axis during the luteal phase?

high progesterone and E2 decrease GnRH, LH, and FSH

91

What happens to the corpus luteum in the presence of low LH?

it is degraded

92

How can the corpus luteum be rescued?

LH equivalent (hCG) produced by the implanted fertilized embryo

93

What does the absence of HCG and LH cause?

decrease in E2 and progesterone, degradation of endometrium, beginning of menses

94

What occurs at the end of the ovarian cycle?

death of the corpus luteum and drop in estrogen and progesterone levels

95

What responds to falling P and E levels, and what does it do in response?

Pituitary responds to falling E and P by increasing FSH secretion

96

What does an increase in FSH secretion cause?

recruits cohort of large antral follicles to enter a rapid growth phase

97

What do the large antral follicles secrete?

low amounts of E2 and Inhibin B

98

what does E2 and Inhibin B do?

negatively feed back on FSH

99

What does a decline in FSH levels do?

cause atresia of all but 1 follicle

100

What does the dominant follicle secrete?

high levels of E2

101

What does high levels of E2 do?

positive feedback on gonadotropes resulting in a LH and (some) FSH surge

102

What does the LH surge do?

induces meiotic maturation, ovulation, and luteinization

103

What does the corpus luteum produce?

high progesterone, along with estrogen and inhibin A

104

What does high progesterone, estrogen and inhibin A do?

negatively feedback on LH and FSH, returning them to basal levels

105

What happens to the corpus luteum?

slowly becomes less sensitive to basal levels of LH, will die if not exposed to LH-like activity (i.e. hCG)

106

What are the three layers of the uterus?

endometrium, myometrium, perimetrium

107

What is the endometrium?

innermost, mucosal layer

108

What is the myometrium?

thick muscular layer

109

What is the perimetrium?

(serosal layer) - outer connective tissue and sersa

110

is the cervix part of the endometrium?

no, it is distinct from the endometrium

111

What is shed during menstruation?

endometrium - the functional zone

112

What leads to the necrosis of the endometrial layer?

reduced blood flow to the spiral arteries (high resistance, low volume) leads to ischemia and necrosis of the endometrial layer

113

What stimulates uterine cell growth

increased E2 during follicular phase

114

What is dominant in the proliferative phase of the endometrial cycle?

estradiol

115

What receptors are upregulated in response to E2 during the proliferative phase?

progesterone receptor

116

What vascular changes occur during the proliferative phase?

increased vascularization

117

What is dominant in the secretory phase of the endometrial cycle?

Progesterone

118

What is a result of high progesterone in the secretory phase?

high progesterone from the corpus luteum has anti-estrogenic effects and stops further uterine growth

119

What do the uterine cells secrete during the secretory phase?

large amounts of carbohydrate rich mucous

120

What vascular changes occur during the secretory phase?

vascularization continues to increase

121

What stromal changes occur during the secretory phase?

stromal cells undergo predecidualization and the stroma become edamatous

122

What is the hormonal state of the menstrual phase of the endometrial cycle?

Low P4 and E2 due to demise of the corpus luteum

123

What is a result of decreased blood flow to the spiral arteries?

ischemia and necrosis of the endometrium

124

How else is the endometrium degraded?

proteolytic enzymes are increased

125

does the released blood clot?

no - the necrotic tissue releases fibrolysins which prevents the blood from clotting

126

What is the total volume loss in menstruation?

~30 mL

127

What hormones dominate in the vagina during the mid- to late follicular phase?

estrogens

128

What is the appearance of the vaginal cells in the follicular phase?

large, squamous, cornified with small or absent nuclei

129

What hormones dominate in the vagina in the luteal phase

progesterone

130

What is the appearance of the vaginal cells in the luteal phase?

small basophilic cells with many leukocytes

131

What are the changes in cervical mucous during the follicular phase?

cervical mucous increases, becomes more alkaline and less viscous

132

what are the changes in cervical mucous during the ovulatory phase?

characterized by spinbarkeit (stretchable mucous)and ferning (fern pattern when dried on a slide)

133

What are the actions of estradiol (E2)?

inhibit growth of cohort follicles

alter cervical mucous to facilitate sperm transport

affect fallopian tube to favor transport of ovum and zygote

prepare endometrium for progesterone to evoke secretory response

prime GnRH action on LH secretion o evoke ovulatory surge of LH

134

What is a primary releaser of E2?

the dominant follicle