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B8W1 > THE MENSTRUAL CYCLE > Flashcards

THE MENSTRUAL CYCLE Flashcards

1
Q

What is the criteria for which women get menstrual cycles?

A 
post pubertal
post menopausal
without POF
healthy weight
not pregnant
not breast feeding
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2
Q

what is POF?

A

primary ovarian insufficiency - when ovaries stop working before 40

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3
Q

describe the mechanism of gonadotropin releasing hormone?

A

released from the hypothalamus and it binds to GnRH 1 receptors which can then elicit downstream signalling in the target cell. acts on the anterior pituitary to cause hourly pulses to make LH and FSH

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4
Q

describe how LH interacts with a cell?

A

it binds to the LH receptor which is a glycoprotein receptor

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5
Q

describe how FSH interacts with a cell?

A

it dimerises and binds to the FSH receptor which is a glycoprotein receptor

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6
Q

what are the 4 classes of steroids?

how do they differ?

A

oestrogen
progestogens
corticosteroids
androgens

by the number of carbons

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7
Q

what are steroid’s biochemical pre-curser?

A

cholesterol (from acetate)

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8
Q

what are hormone’s activity regulated by?

A

receptor levels
hormone production rate
binding proteins
clearance rate of hormones

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9
Q

describe the formation of oocytes?

A

gametes enter the first meiotic stage
eggs reach the stage of diplotene where they form a germinal vesicle
oocytes rest and meiosis stops
meiosis restarts at puberty

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10
Q

what is a primordial follicle

A

a primary oocyte surrounded by a layer of granulose cells, mesenchymal cells and membrane propia

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11
Q

describe the steps of primary follicle formation?

A

the primordial follicle grows and matures in around 70 days to form a primary follicle.

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12
Q

what is a primary follicle?

A

a fully grown oocyte but its still arrested in meiosis

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13
Q

describe the steps of pre-antral follicle formation?

A

primary follicle develops and granulosa cells proliferate to form layers- the outer layer becomes theca cells and oocyte gains the zone pellucid

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14
Q

describe the follicular trickle?

A

if the pre-antral follicles are growing at a pace that matches FSH and LH secretion levels then the follicle can be rescued from atresia and undergo significant growth to the pre-ovulatory phase

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15
Q

describe folliculogenesis?

A

a cavity forms within the granulose cells called the antrum. the antrum expands the oocyte. the oocyte retains a tight linked layer of specialised granulosa cells called cumulus cells

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16
Q

what is the length of the follicular phase of the ovarian cycle?

A

beginning on the first day of menses and ends on ovulation. 1-14

17
Q

how is the follicular phase of the ovarian cycle characterised?

A

by the presence of a follicle

18
Q

what is the length of the luteal phase of the ovarian cycle?

A

from ovulation to last day 14-28

19
Q

how is the luteal phase of the ovarian cycle characterised?

A

when the corpus luteum is present

20
Q

what is the corpus luteum?

A

the remnants of the follicle

21
Q

what happens when GnRH stimulates the anterior pituitary?

A

FSH and LH are secreted.

22
Q

what does LH act on?

A

LH receptor on the theca cells so they can make androgens

23
Q

what does FSH act on?

A

FSH receptors on granulosa cells which causes expression of androgen aromatase (converts androgens to oestrogen). this causes a rise in oestrogen levels

24
Q

what happens when oestrogen levels rise?

A

the release of LH and GnRH are slowed. = negative feedback

25
Q

what do granulosa cells produce when oestrogen levels rise?

A

inhibin B to regulate FSH production

26
Q

what stimulates follicular growth?

A

androgens having an anabolic effect on granulosa cell growth

27
Q

what happens when follicular growth occurs?

A

AMH is produced which regulates growth of neighbouring follicles

28
Q

what happens as plasma oestrogen levels surge past the threshold?

A

it overcomes the negative feedback effect and stimulates production of LH. now LH levels surge and can act on granulosa and theca cells to trigger ovulation.

29
Q

what do granulosa cells release when ovulation is triggered?

A

progesterone

30
Q

what is nuclear maturation of the oocyte?

A

reversing meiotic arrest and driving the progression of meiosis to prepare the egg for activation.

31
Q

outline the basics of egg development?

A

oogonia undergo mitosis until bout 2-4 million form. oogonia then form a primary oocyte. these then begin meiosis 1 and stop in meiotic arrest from both till puberty.
at puberty, the second half of meiosis occurs and the oocyte splits to form a large secondary oocyte and a polar body (has hardly any cytoplasm)
sperm now fertilises egg and meiosis 2 occurs to form another oocyte and polar body.

32
Q

what is oogenesis?

A

creation of eggs whilst in gestation

33
Q

what is ovulation?

A

when an oocyte is pushed out of the ovary

34
Q

describe the luteal phase of the ovarian cycle?

A

the ruptured follicle closes after releasing the egg and forms the corpus luteum, which produces increasing quantities of progesterone

35
Q

outline the uterine cycle?

A

menstrual phase
proliferative phase
secretory phase

36
Q

what happens in the menstrual phase?

A

shedding of uterine lining in absence of preganncy

37
Q

what happens in the proliferative phase?

A

endometrium and myometrium regrow to prepare for possible pregnancy. cervical mural secretions change viscidity and pH

38
Q

what happens in the secretory phase?

A

on day of ovulation, blood supply to endometrial tissue is remodelled, cervical secretions change, progesterone levels rise and prepare the endometrium for implantation

39
Q

what are the effects of oestrogen?

A

maintains body temp
helps against memory loss
regulates production of cholesterol
stimulations maturation of ovaries and start of menstrual cycle, stimulates maturation of vagina and maintains a lubricated and thick vaginal lining, stimulates development of breast and prepares glands for future milk production, stimulates uterus maturation and prepares it to nourish a foetus, helps preserve bone density

B8W1 (9 decks)

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