Infertility physiology Flashcards
How is GnRH released?
synsthesised by neurones in the hypothalamus
released in pulses
What does oestrogen do to the frequency of GnRH release?
increases it
What does prgesterone do to the frequency of GnRH release?
decreases it
Are GnRH pulses constant?
men - YES
females - change during the menstrual cycle
What do high frequency GnRH pulses stimulate?
LH pulses
What do low frequency GnRH pulses stimulate?
FSH pulses
What cells does FSH act on?
granulosa cells
What is the role of FSH in males?
stimulates sertoli cells and spermatogenesis
What is the role of FSH in females?
stimulates follicular development
oestrogen secretion
thickens the endometrium
What is the compostion of FSH?
glycoprotein containing 2 subunits
What is the compostion of GnRH?
deca peptide hormone - neuropeptide
What does LH act on?
theca cells
What is the role of LH in females?
peak stimulates ovulation
thickens endometrium
stimulates corpus luteum development to produce progesterone
What is the role of LH in males?
stimulates Leydig cells
testosterone secretion
spermatogenesis
What is oestrogen secreted from?
primarily the follicles in the ovaries and the adrenal cortex, also by the placenta in pregancy
What is the role of oestrogen?
stimulates endometrium thickening
creates a fertile cervical mucus
What is the role of oestrogen in the follicular phase?
stimulates gonadotrophin secretion
What is the role of oestrogen in the luteal phase?
increased oestrogen inhibits the secretion of FSH and prolactin so decreases the viscosity of the cervical mucus to facilitate sperm penetration and reduces vaginal pH by causing lactic acid production
Where is progesterone secreted from? Why?
the corpus luteum to maintain early pregnancy
Where is progesterone secreted from during pregnancy?
the placenta
What is the role of progesterone?
inhibits LH
responsible for the infertile thick cervicle mucus produced during pregnancy
maintains the thickness of the endometrium
increases basal body temperature
relaxes smooth muscles
What is GnRH pulsitiliy signalled through?
the kisspeptin receptor
How long does the luteal phase last for?
14days
What is oestrogens effect on LH and FSH?
increases them
At what time is GnRH at its peak?
during the night
What is the result of the action of LH on theca cells?
uptake of cholesteral
conversion of androgens to oestrogen
What happens during the follicular phase?
increase in the number of follicular cells and an accumulation of follicular fluid resulting in an increase in the diameter and overall size of the follicle
What is a follicle?
oocyte surrounded by follicular cells (granulosa cells and theca cells)
What is folliculogenesis?
many cells grow under FSH but only one is picked to become the dominant follicle and is selected for ovulation
What does the dominant follicle possess?
most FSH receptors and high vascularity
What volume of oestrogen is reqeuired to stimulate an Lh surge (through increase in GnRH pulses)
200Pg/ml oestrogen
What the formation of the corpus luteum?
formation occurs due to LH
granulosa and theca cells develop in luteal cells
causes an increase in progensterone production due to a delivery of cholesterol
LH stimulates angiogenesis
Where are the sertoli and germ cells found?
seminiferous tubules
How long does spermatogensis take? Where does it occur?
seminiferous tubules
70days
What is the role of testosterone?
maintains the integrity of the blood brain barrier and releases mature spermatoza from Sertoli cells by influecing myoid cells
What is the role of LH on lyedig cells?
LH binds to lyedig cels and stimulates the production of enzymes that synthesise testosterone from cholesterol
What day in the female cycle is the midluteal day?
21
What is oligiomenorrhea?
cycles >35days
What is amenorrhea?
absent menstruation
What is primary amenorrhea?
never had a period
What is secondary amenorrhea?
once had a period, but now they have stopped
What are Group 1,2 and 3 of the WHO classification of ovulatory disorders?
1 - Hypogonadotrophic hypogonadism
2 - PCOS
3 - Premature ovarian failure
What is Hypogonadotrophic hypogonadism?
hypothalamus doesnt produce GnRH so pituitary cannot release LH and FSH, also oestrogen deficiency
What can cause Hypogonadotrophic hypogonadism?
stress excessive exercise low BMI pituitary/brain tumours head trauma drugs - steroids, opiates Kallmans syndrome
What is the diagnostic test for Hypogonadotrophic hypogonadism?
progesterone challenge test - menstrual bleed in response to 5 day course of progesterone indicates normal oestrogen levels
What is the management of Hypogonadotrophic hypogonadism?
BMI >18.5
folic acid 400mcg
rubella immunisation
Hormone therapy - gonadotrophin injections, pulsitile GnRH
What are fibroids?
growths that grow around the uterus
What are the different types of fibroids?
intramural
submucus
pednuculated - massive, sticks out
subserous
What is the treament for fibroids?
hysteroscope
laprascopic myomectomy - for intramural
