Hormonal control of menstrual cycle + disorders Flashcards
What effect does oestrogen have on pit
Low oestrogen inhibits LH release
High oestrogen stimulates it (this feedback loop works by increasing no. of oestrogen receptors)
What effects does progesterone have on pit
Low prog stimulates LH and FSH
High prog inhibits it (this feedback loop works by increasing sensitivity)
What is the most important hormone in follicular stage
FSH ( can rise as O, P and inhibin are low)
What are the two types of cell in follicle
Thecal - make androgens from cholesterol
Granulosa - make oestrogens from androgens (aromatisation) - under influence
What do inhibin and activin do
Both secreted by granulosa cells
Inhibin increases androgen synthesis and down regulates FSH
Activin increases FSH binding onto follicles
What causes LH surge
oestrogen exceeding positive threshold
How and why does ovulation occur
after breakdown of follicle by LH, FSH, proteolytic enzymes and PG
What are the actions of LH
Luteneises follice - makes it start producing prog
Resumption of meiosis
ovulation
Why does corpus luteum degrade
Degrades as prog switches FSH and LH off and there’s no b-hCG to tell it to keep going on
How does menstrual cycle start again
Reduction of P + O and inhibin, brake taken off pituitary and FSH starts again
What change occurs in proliferative endometrial phase
Single layer –> pseudostratified
What happens in secretory endo. phase
Proliferation stops, start secreting stuff into glands and uterine lumen
Formation of decidua (temporary layer)
What are the three layers of endometrium
Basalis (REMAINS)
spongiosum (stroma + exhausted glands)
compactum (decidua)
Definition of precocious puberty
Before 8 in a girl
before 9 in a boy
Definition of delayed puberty
No secondary sexual characteristics by age of 14
Causes of delayed puberty
Central defect:
Anorexia
chronic illness
Kallmann’s
Failure of gonadal function:
turner’s (XX) ovarian dysgenesis
premature ovarian failure
Non structural causes of DSD
Turner's (45X) 46 XY (gonadal dysgenesis due to SRY mutation) androgen insensitivity 5 alpha reductase def CAH
Features of turner’s
wide carrying angle, webbed neck short coarctation of aorta thyroid problems deafness IBD
Why does turner’s lead to DSD
STREAK GONADS
What happen in 46 XY SRY def
absent anti-mullerian hormone so no prevention of development of uterus vagina, fallopian tube.
No testosterone so foetus virilise
What happens in 46 XY DSD with androgen insensitivity
Uterus doesn’t form cause you have AMH
You develop testes due to testosterone
BUT you develop female external genitalia
Will see: female external genitalia, testes descending somewhere, no uterus
What happens in 5-a reductase def
Normal male sexual genitalia but doesn’t virilise properly as you can’t make DHT (ambiguous genitalia)
What happens in 46 XX DSD
Caused by CAH
Virilisation of female
Fused labia, enlarged clitoris
What is primary amenorrhea
Girl that fails to menstruate by age of 16
