physiology- female Flashcards
in ABSENCE of which gene does gonad develop into ovary?
SRY
what are the 2 main stages of follicle growth?
what determines difference between them
folliculogenesis = growth + development of follicles from earliest “resting”
preantral
antral (Graafian)
whether or not they have antrum = fluid-filled space in follicle
antrum = fluid filled space in the follicle
factors controlling initiation of growth and preantral early stages largely unknown
early growth INDEPENDENT of FSH
how long does follicle growth take?
3 cycles (90 days)
ovarian follicle structure:
which part of follicle has FSH receptors?
granulosa cell
remember follicle is dependent on FSH for growth once it develops an antrum
which part of follicle has LH receptors?
theca cell
ovarian steroid production:
- what is produced in theca cell from what?
- what are the enzymes involved?
- which hormone is this dependent on?
cholesterol –> progesterone –> testosterone
17-alpha-hydroxylase
17,20-lyase
- LH
(only theca cells express CYP i.e. enzymes listed above)
ovarian steroid production:
- what is produced in the granulosa cell from what?
- what is the enzyme involved?
- which hormone is this dependent on?
- testosterone –> oestradiol
- aromatase
- FSH
which layers is cholesterol taken into?
granulosa & theca
what produces testosterone in ovarian steroidogenesis?
theca only
what produces oestradiol in ovarian steroidogenesis?
granulosa only
what is 2 cell-2 gonadotrophin theory?
both theca and granulosa cells are required to produce all steroids.
changes in principle hormones during menstrual cycle + accompanying changes in the follicle:
where is GnRH released from?
in what manner i.e. continuous or not?
hypothalamus
pulsatile from puberty onwards
(continuous pre-puberty
where are FSH and LH released from?
anterior pituitary
menstrual cycle:
1. average duration
2. what are the 2 phases?
3. which day is ovulation?
4. which phase is always 14 days long?
- 28 days
- follicular, luteal
- 14
- luteal
what is the main hormone produced in follicular phase?
oestrodiol
what happens in the luteal phase?
which hormone is produced?
formation of corpus luteum from empty follicle
produces progesterone
hypothalamic/ pituitary/ ovarian axis:
luteal/ early follicular phase
what happens?
intercycle rise in FSH (progsterone selectively raises FSH as it declines) - results in selection of dominant follicle
hypothalamic/ pituitary/ ovarian axis:
mid-luteal phase
high progesterone (from corpus luteum) leads to -ve feedback
low LH/FSH (as progesterone becomes >oestradiol)
hypothalamic/ pituitary/ ovarian axis:
mid-follicular phase
granulosa cells in dominant follicle increase in size
- secrete more oestradiol and more inhibin
oestrogen increases
-ve feedback
decrease in FSH
hypothalamic/ pituitary/ ovarian axis:
mid-cyclical
(just before ovulation)
oestradiol >300 for >2days
results in +ve feedback
LH surge
what is effect of luteal surge on oocyte? (2)
- ovulation
- oocyte completes 1st meiotic division
- to remain at max size 2nd set of chromosomes is packaged into 1st polar body
through which process do majority of primordial follicles die?
artresia
99.9999% die
what happens as a result of LH surge?
- blood flow to follicle increases (&so increase in vascular permeability)
- apex/ stigma appears on ovary wall from which egg can be released
- ovulation (release of egg)
- E2 production falls and progesterone is stimulated
these changes in follicle cells = luteinisation
how long after LH surge does ovulation occur?
what happens in ovulation? (3)
18 hours
- oocyte with cumulus cells is extruded from the ovary under pressure
- follicular fluid may pour into the Pouch of Douglas
- egg ‘collected’ by fimbria of uterine tube
- egg progresses down tube by peristalsis and action of cilia
which state of meiosis is oocyte in until ovulation?
meoisis 1
what causes oocyte to become secondary oocyte?
LH surge
2nd meiotic division
- when does it begin
- until when is it arrested?
- ovulation
- fertilisation
what happens to the follicle after ovulation?
it collapses and corpus luteum forms “yellow body”
what does corpus luteum produce?
what kind of receptors does corpus luteum have?
progesterone (but E2 production also increases)
LH receptors (CL is supported by LH in luteal phase even though levels are low then)
how does oocyte pass through fallopian tube?
where in tube does fertilisation normally occur?
peristalsis & action of cilia
ampulla
what happens in fallopian tube in response to cyclical hormone changes?
ciliated cells produce cilia in response to oetradiol
ampulla
once oocyte has passed into uterus progesterone levels increase, cilia retract and glandular cells shorten
what prevents the demise of the corpus luteum if fertilisation occurs?
what is this secreted by?
hCG
the blastocyst
hCG is similar in structure to which 2 hormones?
which receptor does hCG act on?
LH & FSH
LH receptor
fertilisation:
what happens to oocyte when sperm penetrates (3)
- completes 2nd meitoic division (2nd set of chromosomes is packaged into 2nd polar body)
- cortical granules move from cytoplasm to outer edge of oocyte resulting in hardening of membrane - prevents entry of further sperm
- then mitotic division to produce blastocyst
secretions of corpus luteum:
1. progesterone
2. oestradiol
what is the role of each in cycle?
progesterone:
- support oocyte in its journey
- prepares endometrium
- controls cells in the uterine tubes
- alters secrestions of cervix
oestradiol:
- maintains endometrium
what is the lifespan of corpus luteum if fertilisation does not occur?
14 days
removal of CL is essential to initiate new cycle
what are the 2 phases of the endometrium?
which stages of ovarian cycle do these equate to?
proliferative (follicular phase)
secretory phase (luteal phase)
which hormone stimulates proliferative phase of endometrium?
what happens?
which receptors become induced?
oestradiol
maximal cell division, gland expansion, increased vascularity
induction of progesterone receptors
what happens to the endometrium as a result of raised progesterone levels during the secretory phase?
- spiral arteries grow longer
- increase mucous secretion from uterine glands
what happens as a result of increased oestrogen levels during the proliferative phase of the endometrium?
- endometrial thickening
- growth of endometrial glands
- emergence of spiral arterioles
- cervical mucous increases (thinner and more hospitable to sperm)
secretory phase of endometrium
- when does this happen?
- what’s the main hormone invloved?
- what happens
- 2-3 days after ovulation
- progesterone
- reduction in cell divion
- secretion of glycoproteins
- glands increase in tortuoisity and distend
- oedema, increased vascular permeability
- arterioles contract and grow
changes in cells lining uterine tubes
what kind of cells are uterine tubes lined with?
epithelial cells (ciliated and secretory)
increase in height in response to oestradiol mid-cycle
progesterone overcomes E2 effects = decrease in height premenstrual and menstrual
therefore oocytes can only pass during mid-cyle
how is egg moved along tube? (2)
- beating of cilia (stimulated to grow by oestrogen)
- rapid contractions of muscular layer caused by oestrogen
high number of oestrogen receptors present in follicular phase
oestrogen receptors suppressed by progesterone
all of above stops in luteal phase (so even if egg were released it would be unable to pass)
effect of oestrogen in cervix during follicular phase:
- change in vascularity of cervix and oedema
- mid-cycle oestrogen levels cause change in mucuous, now watery
- glycoproteins become alligned and form microscopic channels
- sperm swim up channels
effect of progesterone in cervix during luteal phase:
- reduced secretion and thicker mucous
- glycoproteins now form mesh - acts as barrier (one mechanism of COCP and POP)
what’s the lining of the vagina made of?
what happens to these layers?
stratified, non-keratinised, squamous epithelium
layers shed constantly and flow downwards
where do vaginal secretions come from?
what is their pH?
what is their purpose?
secretions are from cervix and transudation from vaginal epithelium
secretions change with cycle and are acidic providing antimicrobial protection
systemic effects of oestrogen (3)
- vascular tone (reason for hot flushes during menpasue)
- attaining and maintaining bone density
- changes in clotting factors
systemic effects of progesterone (3)
- increased aldosterone production
- catabolic (increases appetite)
- relaxes smooth muscle (uterus)
