PED1003/L20 Female Sex Hormones Flashcards
Describe how nuclear hormone receptors work. (6)
Steroid hormone enters cell
Binds to steroid hormone receptor
Dissociates and dimerises
Translocate to the nucleus
Recruits RNA polymerase II
Transcription & translation
What is the follicular phase?
Day 1-14 in which the follicle is matured
What is the luteal phase?
Day 14-28 in which an environment is created to promote implantation
Give the role of oestrogen in fertility. (3)
Growth of ovarian follicles
Endometrial growth
Increase in tubal motility and uterine contractions
Give the role of oestrogen in lactation. (2)
Stimulation of duct growth
Inhibits milk let-down (prolactin)
Give the role of progesterone in fertility. (3)
Endometrial receptivity
Decrease in Fallopian tube motility
Decrease in uterine contractions
Give the role of oestrogen in secondary sexual characteristics. (3)
Breast development
Female habitus (skeletal, skin, metabolism)
Development of external genitalia
Give the role of progesterone in lactation. (2)
Stimulation of lobuloalveolar development
Inhibits milk let-down (prolactin)
Describe the hypothalamic-pituitary-ovarian axis. (3)
Hypothalamus - GnRH pulsatile release
Anterior pituitary - LH, FSH
Ovary - oestrogen, progesterone
What is the role of the enzyme aromatase?
Converting androgen to oestrogen, driven by FSH
What hormone does oestrogen inhibit?
FSH
What hormone does progesterone inhibit? (3)
GnRH, FSH & LH
Describe the follicular phase of the ovarian cycle. (9)
FSH increasing due to low ovarian hormone production
FSH aids follicular development
Follicles produce oestrogen
High concentration of oestrogen >48h
Positive feedback from increased oestrogen initiated the LH surge
LH surge induces ovulation
Remainder of follicular phase becomes luteinised
Secretes P & O
If not pregnant, CL regresses and decrease in P & O
What occurs after ovulation if no fertilisation occurs? (4)
Corpus luteum regression
P & O levels drop
Endometrium can not be maintained - menstruation
Lack of P means GRH, FSH & LH secretion
What occurs after ovulation if fertilisation and implantation occurs? (5)
Ovum secretes human chorionic gonadotrophin (HCG)
Corpus luteum continues to secrete progesterone
Maintains endometrium and pregnancy
Thicken cervical mucus
Inhibits further secretion of GRH, FSH, LH preventing further follicles developing
Give an example of an ER and PR agonist.
GnRH, FSH, LH all required to induce follicle formation and ovulation
O & P required to feedback on hypothalamus and pituitary and inhibits further follicles being formed
Give an example of a PR antagonist.
Progesterone require to maintain pregnancy
Describe how the combination pill works. (2)
Oestrogen inhibits secretion of FSH via negative feedback, preventing development of ovarian follicle and blocks ovulation by blocking FSH peak
Progesterone inhibits LH by blocking LH surge and makes cervical mucus less suitable for passage of sperm
Describe how the progesterone only pill works. (2)
Inhibits LH and thickens mucus
Blocks ovulation by blocking LH surge
FSH peak still occurs
Describe how the contragestation (abortion pill) works. (2)
Progesterone antagonist
Terminates pregnancy at level of endometrium
Describe how hormone antagonists work. (2)
Tumours arising in hormone sensitive tissues may be hormone-dependent
Growth can be inhibited by hormone antagonists
Give an example of a selective oestrogen receptor modulator (SERM).
Tamoxifen
Give an aromatase inhibitor.
Anastrozole
Describe how tamoxifen works. (4)
Binds to ER to form a dimer
Transported from cytosol to nucleus
Binds DNA to form unstable complex
Hormonal growth signal switched off
Overexpressed estrogen receptors are present in what percentage of breast cancers?
75%
