Week 7 Endocrinology Gonadotrophs Flashcards
How do you tell the difference between and graafian follicle and a primary/ secondary follicle?
If there is a granulosa cell stalk connected to the oocyte this means its a graafian follicle as the oocyte is about to be ejected
What is the function of oxytocin and when is it’s production stimulated?
Oxytocin has major effects on smooth muscle contraction
- milk ejection
- contraction of uterus during childbirth
- Secretion is stimulated in response to stimulation of nipples or uterine distension.
Oxytocin is used to induce labour
In an adult what is the regular pattern of release of GNRH and why?
Pulsing release
- prevents receptor desensitisation & downregulation
What are kiss neurons
A new cell in the hypothalamus that helps regulate GNRH release and is influences but an array of factors including environmental clues, gonads, body fat and the adrenal gland
What is the function of anti mullerian hormone in ovarian function?
It is released by granulosa cells in the early stages of follicle development. So it is a measure of the ovarian reserve (how many follicle are ready to develop).
It can also be high in PCOS as there are many follicles frozen in early development.
What is the purpose of granulosa cells?
They convert androgens made by the theca cells into oestrogen
What is the ezyme found in granulosa cells that converta androgen into oestrogen?
Aromatase
How does a dominant follicle develop?
Everytime FSH is present multiple follicles develop. Eventually one gets mature enough that it stop becoming relient on FSH and begins releasing inhibin B which inhibits FSH
Purpose of FSH?
Stimulates the growth of follicles through the growth of granulosa cells.
This indurectly begine oestrogen production
What is the function of LH in women?
An LH surge triggers the release of the oocyte and ovulation begins.
It is then required in order to form and maintain the corpus leutium which makes progesterone (and some oestrogen) and gets the uterus ready for implantation.
It also stimulates theca cells to make androgens to become oestrogen.
Explain this
What happens to the hormones after pregnency?
hGC is initially made which mimics LH thus keeping the corpus leutium alive and maintaining progesterone production.
Eventually the placenta takes over progesterone.
This begins to stimulate prolactin and thus breatmilk production
What are the different orles of prolactin and oxytocin in milk?
Prolactin is required ot make milk and is also stimulated by suckling.
Oxytocin is required to release milk and is also stimulated by suckling
Secondary function of prolactin?
Inhibits FSH and LH to prevent further pregnecy duirng lactation
In early male development when is the HPG axis active?
Only active during foetal stage and then goes to sleep at birth
What are the foetal cells involved in the male HPG axis?
What do they make and what do they respond to?
Leydig cells -> respond to LH and produce testosterone
Sertoli cells -> respond to FSH and produce inhibin B and AMH
What is the function AMH in male foetal development
Anti-Mullerian hormone (AMH) is produced by testicular Sertoli cells
- Induces regression of Mullerian ducts:
Oviducts
Uterus
Vagina
What are the hallmarks of male hypogonadotrophic hypogonadism?
Low FSH and LH
Low Testosterone
What are the hallmarks of hypergonadotrophic hypogonadism?
High TSH and LH
Low Testosterone
What are these examples of
- Delayed puberty
- Congenital Hypog Hypog
- Brain tumours
- Radiotherapy
Hypog hypog
What are these examples of?
- Klinefelter Syndrome
- DSD/gonadal dysgenesis
- Chemo/radiotherapy
Hyperg hypog
What are the endometrial cells called that proliferate in response to oestrogen?
Endometrial stromal cells proliferate in response to rising estradiol levels from the growing dominant follicle
What are the two phases of endometrial growth?
Proliferative - before ovulation
Secretatory - after ovulation
What is the phase called after ovulation and broadly what happens?
Becomes inflamatory and you get the expression of receptivity genes ready for implantation
What does a disturbance of endometrial receptivity lead to?
- Implantation failure
- Pregnancy loss
- Gynaecological disorders
- Recurrent miscarriage
- Pre-eclampsia
- Intrauterine growth restriction
What causes endometriosis?
Endometrial cells shed via retrograde efflux (up the fallopian tubes) during menstruation