the menstrual cycle Flashcards

1
Q

the first day of menstrual bleeding is designated as

A

day 1 of the menstrual cycle

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2
Q

average menstrual cycle

A

lasts for 28 days (but can be between 21-35 days)

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3
Q

average duration of menses (bleeding)

A

is between 3-8 days and blood loss is around 30ml

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4
Q

functions of the ovary

A
  • generation of mature oocytes (folliculogenesis)

- production of steroid and peptide hormones

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5
Q

cell types within the ovary

A
  • primary oogonia (derived from yolk sac) form follicles
  • granulose cells create oestrogen from androgens supplied by the theca cells
  • ovarian storm which consists of; interstitial cell which become theca cells, theca cells are responsible for converting pregenlone to androstenedione, connective tissue cells and contractile cells
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6
Q

on day 1 of menses

A

all sex hormones are present at low levels (FSH,LH,PROGESTERONE, OESTROGEN) this results in a low level of negative feedback on the hypothalamus which then secretes gonadotrophin releasing hormone which acts on the anterior pituitary to secrete FSH and LH

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7
Q

The LH

A

acts on the granulose cells to produce pregnelone which then diffuses into adjacent theca cells where it is converted to androstenedione

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8
Q

the androstenedione produced

A

then travels back to the granulose cell and is converted oestrogen via aromatase and then to estradiol via 17-beta-HSD

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9
Q

As the FSH and LH levels rise

A

it triggers the development of the follicle into a graafian follicle which can be ovulated

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10
Q

as oestrogen levels increase

A

there is a negative feedback affect on the hypothalamus cause GnRH levels to fall, however at around day 10 the oestrogen levels surpass a certain point and then cause a positive feedback affect on the hypothalamus causing the LH surge triggering ovulation

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11
Q

oestrogen aslo cuases

A

the proliferation of the endometrial lining causing it t become thicker it anticipation of implantation

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12
Q

after ovulation the follicular remnant

A

becomes vascularised and forms the corpus lute

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13
Q

the primary function of the croups luteum is to

A

secrete progesterone which is needed to maintain the endometrial lining

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14
Q

if there is no progesterone

A

then the endometrial lining cannot be maintained and implantation will not occur

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15
Q

the corpus lute remains

A

for around 10 days before it involutes causes menses but if implication occurs then the embryo make HCG which sustains the croups luteum (corpus luteum of pregnancy) which remains for around 10 weeks and producers progesterone until the placenta takes over

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16
Q

a females most fertile period is

A

between days 20-24, if no implantation has occurred by day 24 the corpus luteum involutes and stops secreting progesterone causing progesterone withdrawal

17
Q

progesterone withdrawal causes

A

constriction of the spiral arteries causing endometrial necrosis, which triggers the release of prostaglandins which cause the pain of menstruation and causes smooth muscle contraction

18
Q

everything that occurs after ovulation is known as

A

the luteal phase