Sex Hormones [16] Flashcards
3 sex hormones
Oestrogen
Progesterone
Androgen
What is oestrogen a derivative of and what enzyme converts it
Androgen
Aromatase
GnRH is released from …. Into the …
Hypothalamus
Bloodstream
GnRH travels to …. Which releases ….
Anterior pituitary
FSH and LH
FSH causes release of
Oestrogen
LH causes release of
Progesterone
Progesterone readies the endometrium for
Implanting a fertilised ovum
It inhibits further released of GnRH
Oestrogen causes
Egg maturation
Proliferation of endometrium
Inhibits FSH
What happens after ovulation if there’s been no fertilisation
Corpus luteum regression
Progesterone and oestrogen levels drop
Menstruation
What happens after ovulation if fertilisation has occurred
Ovum secretes HCG
Stimulates corpus luteum to continue secreting progesterone
Maintains endometrium
How do oral contraceptives work
Target negative feedback system clamping secretion of GnRH FSH and LH
Rise in LH is linked to
Ovulation
How does the combined pill work
ER and PR agonist
Oestrogen inhibits FSH secretion - prevents development of follicle
Progesterone inhibits LH secretion - prevents ovulation
How does the progesterone only pill work
PR agonist
Inhibits LH secretion
Stops ovulation
Thickens mucus in cervix
What is used for emergency contraception
Contragestation (abortion pill)
PR antagonist - progesterone is needed to maintain pregnancy
How can anti cancer drugs be hormone linked
Tumours in hormone sensitive tissues (breast) may be inhibited by sex hormones antagonists
What is tamoxifen used for
Breast cancer
It’s a selective estrogen receptor modulator
Tamoxifen mechanism of action
Competitive inhibitor of estradiol for ER
Binds to ER
Hormonal growth signal switched off
Reduced cell proliferation
What triggers testosterone production
LH acts on testes
What receptor does testosterone bind to
Androgen receptor
How do GnRH antagonists block testosterone production
Bind to GnRH receptors on anterior pituitary
Blocks GnRH binding
Blocks release of LH
