Infertility physiology Flashcards by Alison Gourlay

How is GnRH released?

synsthesised by neurones in the hypothalamus

released in pulses

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What does oestrogen do to the frequency of GnRH release?

increases it

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What does prgesterone do to the frequency of GnRH release?

decreases it

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Are GnRH pulses constant?

men - YES

females - change during the menstrual cycle

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What do high frequency GnRH pulses stimulate?

LH pulses

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What do low frequency GnRH pulses stimulate?

FSH pulses

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What cells does FSH act on?

granulosa cells

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What is the role of FSH in males?

stimulates sertoli cells and spermatogenesis

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What is the role of FSH in females?

stimulates follicular development
oestrogen secretion
thickens the endometrium

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What is the compostion of FSH?

glycoprotein containing 2 subunits

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What is the compostion of GnRH?

deca peptide hormone - neuropeptide

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What does LH act on?

theca cells

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What is the role of LH in females?

peak stimulates ovulation
thickens endometrium
stimulates corpus luteum development to produce progesterone

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What is the role of LH in males?

stimulates Leydig cells
testosterone secretion
spermatogenesis

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What is oestrogen secreted from?

primarily the follicles in the ovaries and the adrenal cortex, also by the placenta in pregancy

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What is the role of oestrogen?

stimulates endometrium thickening

creates a fertile cervical mucus

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What is the role of oestrogen in the follicular phase?

stimulates gonadotrophin secretion

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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

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Where is progesterone secreted from? Why?

the corpus luteum to maintain early pregnancy

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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?

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