Female hormone Flashcards
What hormones does hypothalamis produce
GnRH
Oxytocin
what are the 3 Pituitary hormones
LH
FSH
Prolactin
Gonadal hormones in females are
estradiol
progesterone
inhibin
relaxin
testosterone
Uterus/placenta hormones in females (about 5)
PGF2a
progesterone
relaxin
chorionic gonadotropins
pacental lactogen
What is the HPG axis
hypothalamic pituitary gonadal axis
regulated production of reproductive hormones in both sexes
positive and negative feedback loops (different to males)
3 specialised portions in the hypothalamus are:
- surge centre (GnRH)
- Tonic centre (GnRH
- para-ventricular nucleus (secrete oxytocin)
Tonic and surge centre: how do these effect patterns of GnRH secretion amounts?
tonic = slow drip GnRH
surge = rapid and fast flood of GnRH
- very important as created a pre-ovulatory LH surge -> trigger for ovulation in females*
What is the importance of the surge centre in females for hormones?
Surge centre: rapid release of GnRH
-> very important as created a pre-ovulatory LH surge -> trigger for ovulation in females*
What does LH bind to (what cells)
LH binds to theca interna cells to produce testosterone
What does FSH bind to in females?
FSH binds to FSH receptors in Granulosa cells, which drives conversion of T to estradiol
Role of LH
produce testosterone in theca cells
role of FSH
drive conversion of T to estradiol
Estrogen verse estradiol
Estradiol (E2) is major estrogen
- sometimes used interchangably
- two other forms of estrogen (Estrone E1 and Estriol E3
What does production of estradiol require
2cells and 2 gonadotropins:
- theca and granulosa cells
- LH and FSH
Actions of estradiol in the brain
- induced mate seeking behaviour
- makes females receptive to mating
actions of estradiol in female tract
- outward signs of receptivity (red, swollen vulva)
- primes tract for mating (mucus etc.)
- prepares for possible pregnancy (uterine glands, tone for transport, cilia/fluid in oviduct)
As a whole, what stage is estradiol a key hormone for?
mating
What are the 3 important negative feedback loops of HPG axis
Inhibin blocks FSH secretion by AP
E2 blocks FSH secretion by AP
Low E2 and high P4 limits GnRH secretion
What is the 1 important positive feedback loop in HPG axis
High E2 (with no P4) promotes a surge of GnRH at a threshold concentration
What are the feedback mechanisms important for in the HPG axis?
- Regulate hormone production which is critical for follicle maturation and ovulation
LH in corpus luteum: what does LH binding lead to in the corpus luteum?
LH binds to LH receptors in luteal cells → produces progesterone instead of testosterone
Actions of progesterone
- Mammary glands
- endometrium development
- myometrium (decreases uterine tone)
- brain (inhibits receptive behaviours)
What is progesterone important for in the surge and tonic centre? (think negative)
- in tonic centre = reduced pulse frequency
- In surge centre = blocks surge completely
- thus progesterone will block ovulation if high → no ovulation
What happens if progesterone is high
Progesterone will block ovulation, so a corpus luteum needs to degenerate before ovulation can actually occur (because progesterone is produced here by LH*
When is oestrogen at its peak??
Just before ovulation → E2 drive GnRH surge which causes LH surge leading to ovulation
When do we have a rise in progesterone
after ovulation, a developing CL causes increased P4 to try maintain pregnancy
Relationship between LH and estrogen that differs from males relationship between LH and T
- Small pulses of LH and E2 remains low between ovulations (doesn’t have a peak straight after LH like T does in males..)
- prior to ovulation, E2 peaks due to follicle development, causing GnRH and LH surge
What are the 2 cells and 2 gonadotropins involved in producing estradiol
theca interna and granulosa
FSH and LH
Prostaglandin F2a or PGF2a - what process does this hormone drive?
- Luteolysis - the luteal phase
- made by the uterus but has action on CL in the ovary
How does prostaglandin F2a hormone go from uterine to ovary
by counter current exchange between the uterine vein and the ovarian artery to get to the CL of the ovary
What are chorionic gonadotropins
- gonadotropins produced by placenta
- only produced in women (hCG) and mare (eCG/PSMG)
- Lh/FSH like activity in other species
Where is oxytocin produced and what does it stimulate?
- hypothalamus and ovary in CL
- positive feedback loops with PGF2a → drive luteolysis
- stimulates contractions during parturition and lactation (milk let down)
relaxin - where is it produced and what does it cause
produced by placenta in CL
causes softening of pelvic ligaments and cervix for parturition
