Endocrine - the Menstrual cycle Flashcards
(25 cards)
which 3 body parts are involved in the menstrual cycle
hypothalamus, pituitary and ovaries
what hormones are involved
GnRH, FSH, LH, estradiol, progesterone
what are the 2 phases of the menstrual cycle
- follicular phase (maturation of egg)
2. luteal phase
does the follicular phase begin when oestrogen levels are high or low
follicular phase begins when the oestrogen levels are low
what hormones does the anterior pituitary secrete to develop the follicle
FSH and LH
what causes the uterine lining to thicken in the follicular phase
the granulosa cells around the egg enlarge
what hormone do the granulosa cells release when they enlarge
oestrogen
each follicle has the potential to release an egg for fertilisation. true?
true
when does ovulation occur in the follicular phase
ovulation occurs at the peak of follicular growth, in response to LH surge
how long are LSH and FSH released before the oocyte is released
3-4 days
describe the process that allows release of ova into the Fallopian tubes
the wall of the follicle is digested by proteolytic enzymes.
this causes the follicle to rupture and release ova into Fallopian tubes
what is the luteal phase also known as
the secretory phase
why are the granulosa cells now yellow
due to the cholesterol
what are the granulosa cells called in the luteal phase and what do they secrete
they are called the corpus luteum and secrete progesterone
the granulosa cells undergo luteinisation
when is peak progesterone production noted
1 week after ovulation takes place
what happens in menstruation to the corpus luteum and the progesterone levels
if there is no embryo, the corpus luteum begins to disintegrate
progesterone levels are reduced
the uterine lining detaches and menstruation begins
what does the follicular phase end with
ovulation
describe the differences in hormone release in follicular phase and luteal phase
oestrogen secreted in follicular phase
progesterone secreted in luteal phase
describe the hormonal control of ovarian and menstrual cycles
GnRH (hypothalamus) –> acts on ant pit –> secretes FSH and LH
what is the role of FSH
acts on ovaries
stimulates development of follicles
stimulate secretion of estradiol and ovulation
what is the role of LH
acts on ovaries
stimulates follicle maturation, ovulation and development of corpeus luteum
what hormone suppresses FSH production by the ant pit in order to select a dominant follicle
oestrogen
at mid cycle in the luteal phase, what causes the surge of FSH and LH from anterior pituitary
the high levels of oestrogen at mid cycle causes hypothalamus to GnRH - this causes the surge of FSH and LH
how is ovulation detected
most commonly LH measurement
at day 21, progesterone can also be used
