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Block 8 Ellen > The menstrual cycle L5 > Flashcards

The menstrual cycle L5 Flashcards

1
Q

endocrine control involves 3 things

A

neuropeptides
glycoproteins
steroids

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2
Q

what is the neuropeptide involved in endocrine control

A

GnRH

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3
Q

what is GnRH

A

gonadotropin releasing hormone

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4
Q

where is GnRH released from

A

the hypothalamus

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5
Q

structure of GnRH

A

decapeptide (10 aa)

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6
Q

where does GnRh bind

A

to GnRH receptors expressed in the anterior pituitary gland

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7
Q

3 main glycoproteins controlling endocrine function

A

LH (luteinizing hormone)
FSH (Follicle stimulating hormone)
CG Chorionic gonadotropin

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8
Q

what are all three glycoproteins

A

heterodimers

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9
Q

what is the key difference in FSH and LH

A

share the same alpha chain but different beta chains

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10
Q

what does the difference in beta chains between FSH and LH mean

A

they can act on different receptors

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11
Q

what also acts on the LH receptor

A

CG

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12
Q

what type of receptors are the LH and FSH

A

G protein coupled receptors

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13
Q

whats the common biochemical pre-cursor for steroids

A

cholesterol

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14
Q

what is cholesterol made from

A

acetate

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15
Q

four classes of steroids

A

progestogens
androgens
Oestragens
corticosteroids

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16
Q

how many carbons does progestogens have

A

21

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17
Q

how many carbons do androgens have

A

19

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18
Q

how many carbons do oestragens have

A

18

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19
Q

what is the common synthetic pathway for steroids

A

acetate—>cholesterol—> common precursor pregneolone

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20
Q

what class is pregneolone

A

progestogen

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21
Q

what is the precursor of the oestragens

A

androgens

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22
Q

where does cholesterol synthesis take place

A

mitochondria

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23
Q

how do neuropeptides and glycoproteins act

A

on specific receptors

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24
Q

how do steroids act

A

can go directly through the nucleus

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25
Q

biggest sex organ=

A

brain

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26
Q

how often is GnRH released after puberty

A

in hourly pulses

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27
Q

what cells does GnRH act on

A

gonadotrophs

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28
Q

what are Oocytes contained in

A

pre-ovulatory follicles

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29
Q

when is Oocyte number fixed

A

at birth

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30
Q

how many eggs do we have at birth

A

2 million germ cells

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31
Q

what happens in the absence of the SRY gene

A

the coelomic epithelia condense around the PGC forming primordial follicles making them stop mitosis

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32
Q

what happens when the primary follicles stop mitosis and begin meiosis

A

the numbers are fixed

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33
Q

what stage of meiosis do the primary follicles arrest in

A

half way through meiosis 1 –> DIPLOTENE (prophase 1)

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34
Q

what are they called when they arrest in diplotene

A

primary oocyte

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35
Q

what happens to many primary follicles before birth

A

they die

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36
Q

at what point in development are there no more PGC being produced

A

after 3 months post conception

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37
Q

when does proliferation by mitosis happen

A

all completed by birth

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38
Q

when does genetic shuffling by meiosis happen

A

starts in fetal ovary, arrests and restarts at puberty

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39
Q

when does cytodifferentiation happen (making a specialised cell)

A

completed during ovarian cycle

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40
Q

in a preadolescent what is the hypothalamus like

A

immature hypothalamus releases slow pulses of GnRH

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41
Q

what do the slow pulses of GnRH from an immature hypothalamus mean

A

minimal FSH and LH production from pituitary so
no spermatogenesis in male
no ovarian follicle development in females
so…..no testosterone or oestradiol

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42
Q

what is a primordial follicle

A

primary oocyte

surrounded by a single layer of granulosa cells

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43
Q

what happens to primordial follicles at puberty

A

they begin to grow

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44
Q

what does the primordial follicle grow to form

A

primary follicle

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45
Q

the difference in primordial follicles and primary follicle

A

primary follicle produces thick glycoprotein coat= Zona pellucida

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46
Q

what does the primary follicle form into

A

preantral follicle

47
Q

what is the preantral follicle characterised by

A

proliferation of the granulosa cell

48
Q

how are a lot of follicles lost

A

by atresia (degeneration of immature follicles)

49
Q

What can rescue follicles from atresia

A

LH and FSH

50
Q

what does the preantral follicle form

A

the antral follicle

51
Q

what is the antral follicle characterised by (3)

A

the appearance of the antrum
proliferation of granulosa cells
theca cell present

52
Q

what is the antrum

A

fluid filled cavity

53
Q

three types of cell in the antrum=

A

Oocyte
theca cell
granulosa cells

54
Q

what are the major hormones regulating female reproductive cycle (3)

A

FSH
LH
GnRH

55
Q

when is the Oocyte number fixed

A

3 months post conception

56
Q

what is the name of the structure unit in which the oocyte develops

A

the follicle

57
Q

at what stage of development are Oocytes at birth

A

arrested in prophase 1 primary oocytes residing in primordial follicles

58
Q

what is the pattern of GnRH release in the prepubertal female

A

irregular

59
Q

what is the pattern of GnRH release in the postpubertal female

A

hourly intervals

60
Q

at what stage of follicle development does ovulation occur

A

tertiary, preovulatory

61
Q

how many phases does the ovarian cycle have

A

2

62
Q

what are the 2 phases of the ovarian cycle

A

luteal

follicular

63
Q

what characterises the luteal phase

A

progesterone

64
Q

in the follicular phase what hormone is released first

A

GnRH

65
Q

What does GnRH do

A

cause secretion of FSH and LH from anterior pituitary

66
Q

What cells have receptors for LH

A

Theca cells

67
Q

what cells have receptors for FSH

A

granulosa cells

68
Q

what does the binding of LH to theca cells cause

A

the synthesis of androgens

69
Q

what do the granulosa do with the androgens from the Theca cells

A

make oestrogens using aromatase

70
Q

whats is the oestrogen called that the granulosa cells make

A

Oestrogen 217 beta

71
Q

where is Oestrogen 217 beta (E217B) released

A

into the plasma but with a short half life

72
Q

what does E217B (oestrogen) do

A

acts on the anterior pituitary and hypothalamus in a negative feedback loop to regulate LH and FSH production

73
Q

what other substance do the granulosa cells produce

A

inhibin B

74
Q

What does inhibin B do

A

inhibits the production of FSH from the anterior pituitary

75
Q

what effect do the androgens have on the granulosa cells

A

cause proliferation increasing the number of granulosa cells so the follicle grows

76
Q

in females when is AMH produced and why

A

post puberty, to regulate the growth of neighbouring follicles

77
Q

When a follicle expresses FSH and LH receptors that are acted upon what does it become

A

the dominant follicle that suppressing follicles around it

78
Q

what does the sharp increase in granulosa cells cause

A

a sharp rise in oestrogen levels—> plasma oestrogen surge

79
Q

how does oestrogen act on granulosa cells

A

in response to high oestrogen levels granulosa cells express LH receptors

80
Q

when Oestrogen is in very high levels and reaches the threshold what happens

A

stops negatively inhibiting LH and FSH causing a peak in LH levels

81
Q

what does the peak in LH levels do

A

triggers ovulation

82
Q

what does the peak in LH levels do (2)

A

triggers ovulation

progesterone production in granulosa cells

83
Q

overall when E2 is low it does

A

negative feedback

84
Q

overal when E2 is high it does

A

positive feedback

85
Q

whats it called when the oocyte resumes meiosis and undergoes division

A

nuclear maturation

86
Q

how would you describe the division in nuclear maturation

A

unequal, most cytoplasm retained in secondary oocyte

87
Q

how much chromosome is lost on the 1st polar body in meiosis

A

half

88
Q

what does the presence of a polar body in an oocyte mean

A

the oocyte is ready to be fertilised

89
Q

in second meiosis when does the oocyte arrest

A

metaphase

90
Q

what happens in oocyte maturation

A 
cytoplasmic maturation (reorganised) 
-mitochondria and cortical granules relocate to periphery
91
Q

what happens at the same time as oocyte maturation

A

associated granulosa cells expand

92
Q

what is it called when granulosa cells expand

A

cumulus cell expansion

93
Q

what happens at the start luteal phase

A

ruptured follicle forms corpus luteum

94
Q

what does the corpus luteum secrete

A

oestrogen and progesterone

95
Q

how many days does the luteal phase last

A

14

96
Q

what happens in the corpus luteum

A

all the cells of the corpus luteum now express LH receptor, production of oestrogen and rising levels of progesterone —-> negative LH feedback

97
Q

what happens to the luteal phase after 14 days

A

it stops unless there is fertilisation and corpus luteal degrades

98
Q

leutolysis=

A

break down of the corpus luteum

99
Q

three stages of the uterine cycle

A

menstrual phase
proliferation phase
secretory phase

100
Q

what happens in the menstrual phase

A

shedding of uterine lining

101
Q

what happens in the proliferation phase

A

endometrium and myometrium begin to regrow

increase cervical mucal secretions

102
Q

what happens in the secretory phase

A
  • blood supply to the endometrial tissues remodelled
  • Cervical secretions change again
  • supported by progesterone
103
Q

how many days does it take for the epithelium to be re-epithelialized

A

4-7 days after the beginning of menstruation

104
Q

what do progesterones do to the endometrium

A

cause swellings and secretory development of the endometrium (prepared for implantation)

105
Q

what is menstruation caused by

A

the absence of a pregnancy

106
Q

what is the most potent oestrogen

A

17-b estradiol

107
Q

where does 95% of oestrogens come from

A

granulosa cells

108
Q

when happens when you run out of eggs

A

you run out of oestrogen

109
Q

what are menopausal symptoms principally caused by

A

lack of oestrogen

110
Q

example of 3 menopausal symptoms

A

sleep disturbance
menstrual irregularity
hot flushes

111
Q

3 long term problems with menopause

A

osteoporosis
dry vagina
alzheimer’s

112
Q

In HRT what is oestrogen usually prescribed with and why

A

progesterone

because oestrogen alone stimulate endometrial hyperplasia and carcinoma

113
Q

who can take oestrogen only pills

A

women who have has a hysterectomy

114
Q

risk of HRT (4)

A

thrombosis
breast cancer
cardiac disease (older women)
Alzheimers

Block 8 Ellen (14 decks)

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