female physiology Flashcards
Identify the major female reproductive hormones, the structures responsible for their synthesis and describe their endpoint actions
already know the others
Gonadal -
Estradiol (E2)
Progesterone (P4)
Explain the HPG axis, including feedback mechanisms
GnRH- surge centre, tonics centre
PVN - oxytocin
FHS + LH = AP
Oxytocin = PP
Surge centre vs tonic (one does big surges and on does some small drops)
Surge = LH surge = pre-ovulatory LH surge (why not in male)
Follicles
LH binds to Theca interna cells (outside of basement membrane) —> cause these cells to produce testosterone
FSH binds to granulosa cell ( in the zone granulosa), drives T to estradiol
Estradiol action (key at mating)
brain, female tract (bull shit here)
Inhibit, E2 - blocks FSH (negative feedback)
Low E2 + high P4 limits GnRH secretion
Postive feedback loops - high E2 on surge centre = surge = ovulation = (follicle positive feedback on E2)
LH bind to luteal cells of the corpus luteum = P4 production
Progesterone
Secreted from the CL
acts on mammary glands +, endometrium +, myometrium - ( decrease tone), brain -ve m behaviours.
P4 is about suppression of GnRH = blocks surge, reduce pause on tonic. Therefore there is no ovulation will occurring when a CL is present.
PGF2a
Causes luteolysis -
Produced = utrine endometrium
Delivered vis uterine vein and ovarian artery counter current
Other relevant hormones
explain the four phases and how the hormones interact
Define the phases and stages of the estrous cycle
Oestrus cycle can be divided into
Follicular phase (E2 dominant), ends at ovulation, 20% total time.
Luteal phase (P4 dominant), CLs on ovary, ends at luteolysis (80% of cycle)
Stages of estrous cycle
Proestrus - follicular phase, follicle growth, increasing E2, decreasing P4.
Estrus - follicular phase, sexual receptivity, peak E2.
Metestrus - Luteal phase, CL formation, Increasing P4, decreasing E2
Diestrus - luteal phase, full fx CL, sustained high P4
Describe how behaviour and hormones change across different phases/stages of the oestrus cycle characteristics
Anestrus
Anestrus - low E2 and P4 - from insufficient GnRh release (no ovulatory follicles, no corpora lutea)
first ovulation after anestrus is often silent ( no P4 priming)
Define monoestrous and polyestrous, including which species are monestrous and polyestrous
seasonality is driven by daylight and melatonin secretion
Describe the concept of reproductive seasonality, including which species are short and long day breeders
Cows - polyestrous
Sheep - short day breeder (Dec-june in Aus)
Horse - long day breeder (sep- mar in Aus)
Pig - polyestrous
often this is due to gestation length. so the female can have the energy to lactate
Canine estrus cycle difference
Estrus cycle for the feline
take home points of lecture 2
Explain the process of folliculogenesis, describing the impact of. Hormone signalling on follicle recruitment, selection, dominance and atresia
before follicular phase can occur, luteolysis needs to occur so progesterone becomes low. So it no longer inhibits GnRH secretion and LH surge.
Folliculogenesis
Initial recruitment phase
Primordial to early antral follicle
Autocrine/paracrine control as happens all life (before puberty)
Cyclic recruitment phase
Antral to ovulatory follicle
Occurs each cycle
Driven by FSH/LH
Takes 10 days.
Folliculogenesis
Initial recruitment phase
Primordial to early antral follicle
Autocrine/paracrine control as happens all life (before puberty)
Cyclic recruitment phase
Antral to ovulatory follicle
Occurs each cycle
Driven by FSH/LH
Takes 10 days.
list the four steps of folliculogenesis
Recuirtment
selection
dominance
the ones that do not progress are called Atresia
Follicle recruitment
Cohort of astral follicles recruited
Small follicles
E2 secretion begins
This is FSH dominant here
Selection
A small group of recruited follicles start to develop t medium size
LH receptors starting
FSH still plays a roll
Dominance
Only a few of 1 becomes the dominant
E2 secretion highest - thus completely dependent on LH
Inhibit secretion begins to block other follicles.
LH is key to final maturation of follicles
Thus the driving force of a follicles success is its expression of LH receptors.
Atresia
Along each of the phases where cells to not go the next phase they undergo Atresia - degeneration.
Explain the concept of follicular waves
Describe the process of ovulation, including the normal controls and induced ovulation
Leading up to ovulation
leutolysis = decrease progesterone
GnRH/LH pulses increase in frequency
Increase in E2 by Theca interna cells and granulosa cells (as more of these cells are being developed as the follicle maturates)
Once E2 reaches threshold it causes a GnRH/LH surge
That causes ovulation
LH surge = causes the following cascade
Prostaglandin E2 (ovary Sec)
tissue remodelling + increased blood flow
Prostaglandin F2a ( Ovary Sec) - note different to endometrium secretion
Smooth muscle contraction
Connective tissue breakdown
Progesterone - produced by theca cells
weakens follicle walls
These pressure are what causes ovulation
Induced ovulators = mechanical stimulation for LH surge
Explain the process of oogenesis, including prenatal and post-pubertal stages
Cumulus-oocyte complex (con) is what is secreted out.
Prenatal-
Go to primordial follicles prior to birth and stops till puberty
Post-LH surge
primary oocyte becomes M2 oocyte by spitting out a polar body of unwanted DNA
Fertilisation- second meiotic division
makes a second polar body before fertilisation, so is a haploid cells right before ovulation.
BIG difference = Canines only resume meiosis after ovulation. ( so both 1 and 2 metic divisions are in estrus, thats why fertilisation needs to occur after a few days
follicualar phase take home points
Major events of in the luteal phase
Luteinisation (CL formation)
Progesterone secretion (CL fx)
Luteolysis (CL destruction)
Describe the formation fo the corpus luteum and explain its purpose
Progesterone secretion efficiency = number of cells and amount of vascularisation
Explain the local and systemic actions of progesterone produced by CL
Progesterone production from cholesterol and LH at basal levels as signalling tonic centre.
