Menstrual Cycle Flashcards
what is the purpose of the menstrual cycle
generate oocyte
facilitate fertilisation
optimise endometrium for implantation
protect developing embryo
what is the beginning of the menstrual cycle called for the first time
menarche
what is it called when you don’t have a menstrual cycle anymore
menopause
what is the follicular phase
easy 1 to 14 and on the list day the oocyte is released
menstruation occurs for first couple days then endometrial thickness starts to increase
what is the luteal phase
day 14 - 28 where the cops luteum breaks down and the endometrial thickness increases with glands and blood vessels forming
what are the days of the menstrual phase
proliferative phase
secretory phase
men - 1 - 5
pro - 5 - 14
sec - 14 - 28
describe the hypothalamo-pituitary-ovarian axis
the hypothalamus send GnRH to the anterior pituitary. AP then released FSH and LH to the ovary
the ovary then releases oestrogen which acts on the anterior pituitary and hypothalamus
describe the structure and role of GnRH from the hypothalamus
decapeptide
secreted by mid basal hypothalamic neurones
hourly pulses
transported to pituitary via hypophyseal portal blood system
what factors can effect secretion of GnRH from the hypothalamus
bereavement anxiety time zone day/night duty exercise weight loss/gain
what cells secrete FSH and LH in the anterior pituitary
basophils
what is the structural difference between FSH and LH
FSH has A and B with 4 N’s
LH has A and B but with 3 N’s
what is the role of FSH after release from the anterior pituitary
stimulates follicular activity
thus promoting estradiol production from granulose cells
What is the role of LH after release from the anterior pituitary
triggers release of egg from dominant follicle
promotes development of the corpus luteum and the production of progesterone
what is the negative feedback effect of rising oestrogen
inhibits GnRH, LH and FSH
during the start of the cycle
what is the positive feedback effect of rising oestrogen
nearing mid cycle high oestrogen (E2) leads to surge in LH which triggers ovulation
what is the difference in the number of primordial follicles in a 6 month foetus, at birth and puberty
2,000,000
750,000
400,000
how many primordial follicles actually develop and produce an egg
450
no new follicles develop
describe the terminology of development from primordial follicle to ovulation
primordial follicle primary/prenatal follicle secondary/antral follicle preovulatory follicle ovulation
what does proliferation of granulose cells lead to
development of antrum (fluid)
what allows communication between oocyte and granulose cells eg passage of low mw materials
gap junctions and cytoplasmic processes
what is the difference between theca internal and theca externa of follicular development
granular and highly vascularised - interna
fibrous capsule - externa
what is secreted by theca interna cells
androgens
what are androgens converted to in granulosa cells
androgens convert to estradiol 17- B
what is the role of an empty graafian follicle
granulose cells undergo lutenisation producing the corpus luteum - this then produces progesterone and estradiol 17 b
what happens to the corpus luteum if there is no fertilisation
corpus luteum degenerates / fibroses to become corpus albicans
what are the 4 cycles within the menstrual cycle
gonadotropic hormone levels
ovarian cycle
ovarian hormone levels
uterine cycle
what is the endometrium
lining of uterus
what happens to the endometrium during the proliferative phase
endometrium thickens
increase in stroll cells, glands and blood vessels
what is the thickness of the endometrium during ovulation
2-3 mm
what happens to the endometrium during the secretory phase
progesterone is the dominant hormone increase in secretion increase in lipids and glycogen increase in supply 4-6 mm thick
why is the endometrium optimal for implantation during the secretory phase
stable
vascular
nutrient rich
what happens during menstruation
vasodilation (vasospasm of blood vessels due to PGF2a)
necrotic outer layers of endometrium separate from uterus
separated tissues and blood unities uterine contractions which leads to expulsion of contents
what is mucus, where does it come from and what does it do
produced from columnar glands in the cervix
stringy and runny midcycle (spinnbarkeit)
facilitates sperm access at ovulation
what is the role of mucus within the cervix
tenacious and inelastic in luteal phase
prevents microbial ingress and protects developing embryo
critical to pregnancy as develops mucus plug
what is the range for optimal timing of oval in the menstrual cycle
from about 7 to 18 days but most at day 13/14
what is within the combined oral contraception
estradiol and synthetic progesterone
how does the pill stop ovulation
inhibits GnRH, FSH and LH which prevent ovulation, keep the endometrium thin and mucus tenacious
how do you induce super ovulation
daily injections of FSH
originally extracted from urine of meopausal nuns but now use recombination FSH
