Endocrinology of the menstrual cycle Flashcards
When throughout life does GnRH activity increase
Puberty in females
what does FSH do
follicle stimulating hormone - stimulates growth of egg before ovulation
what does LH do
lutinising hormone trigger release of the egg
what does the ovarian follicle secrete
oestrogen( increase LH)
what is the endometrium
inner lining the uterus - each month it thickens then if no pregnancy it sheds in a process called menstruation. if contraception occurs the embryo implants in the endometrium
what do the ovaries do
glands that produce egg and hormones - contain follicles and attached to the uterus by the Fallopian tubes - made of ovarian follicles like eggs in a sac
what is contained inside an ovarian follicle
oocyte and cells that release oestrogen and progesterone
during the development of the ovarian follicle what type of follicle contains the primary oocyte
primordial follicle
13-50 years
what part of meiosis is the primary follicle rested in
prophase 1
what does the graphian follicle contain
secondary oocyte
how does the second devision need to be completed
ovum needs to be fertilised
how long does the follicular phase last
1-7/8days
in the follicular phase what hormone determines what regulation should be applied by negative feedback
oestrogen
what hormone inhibits cells that make FSH
inhibin
in the late follicular phase when 1 follicle is secreted wha hormone is produced in high levels
oestrogen
when the amount of oestrogen changes in a system what does oestrogen do
changes to psotivie feedback and increased production of other hormones so have surge in LH and FSH
why is the FSH surge not as high as the LH surge in the late follicular phase
because inhibin is produced from the mature follicle/graphian to negatively inhibits FSH producing cells
What hormone starts meiosis in oocyte and acitvates the endomeitrium and dissolves the follicle and promotes vascular leakage causing it to swell and rupture causing ovulation to occur so oestrogen levels plummet
LH
When a mature follicle ruptures what does it release
secondary oocyte and a polar body
how does a corpus luteum form
what does it secrete
remnants of the ruptured follicle - lutinization
appears yellow
progesterone - dominant
what does progesterone do
inhibits FSH and LH so stops further follicle development and ovulation in the current cycle
prepares uterus for pregnancy
in the luteal phase what hormones are stimulating
progesterone - keep LH and FSh down
oestrogen - moderate positive feedback but not as dominant
if fertilisation does not occur what happens
what happens to CL
and hormones
CL degenerates progesterone falls uterus loses endocrine support menstruation FSH and LH get to work again
if fertilisation does occur what happens
what hormone maintains the CL
CL maintained by hCG ( human chorionic gonadotrophin) - maternal recognition of pregnancy produced by trophoblast cells surrounding a growing embryo which eventually forms placenta and become cl of pregnancy
maintains uterine lining until placenta takes over at 3 months
what is the chorion
double layered membrane formed by trophoblast cells and the extra-embryonic mesoderm
what is the function of combined hormonal contraceptives CHC
inhibit ovulation - oestrogen and progesterone no surge of others so no ovulation
have contraceptive effect on cervical mucus and endometrium too
oestrogen causes endometrium to proliferate and grow
progesterone prevents hyperplasia ( excessive growth) of Endometrium
Which one of the phases represents the changes in ovaries during menstrual cycle?
Follciluar phase
Menstrual and secretory are changes in the uterus
High concentration of oestrogen is responsible for the LH surge which causes ovulation during the middle of menstrual cycle.
Which hormone specifically inhibits Follicle-Stimulating Hormone (FSH)
inhibin
How does low concentration of oestrogen regulates hormone production by hypothalamus and pituitary in early follicular phase?
Through negative feedback
Positive feedback later on
High concentration of oestrogen is responsible for the LH surge which causes ovulation during the middle of menstrual cycle. true or false
True- grpahian follicle for prodcution of follicle brining back postive feedback - repsobilbe for ovulation (lH)
Which hormone has a dominating effect on controlling GnRH, FSH and LH production in the Luteal phase?
Progesterone
Both esotrgne and progesterone are produced in the luteal phase
what are the two layers of the uterus
endometrium - internal layer
myometrium - external smooth muscle layer
what does oestrogen prepare
Oestrogen prepares the way:
promotes growth of endometrium & myometrium
promotes formation of progesterone receptors
in the luteal phase progesterone acts on oestrogen - primed endometrium to do what
Loosens and softens connective tissue - makes implantation easier
Promotes secretion of nutrients (glycogen)
Quietens uterine activity
what happens if fertilisation dosent occur be specific
what happens to vessels to cause tissue death
No occupants..no hCG so Corpus Lutem degenerates
Progesterone (and oestrogen) support lost
Uterine prostaglandins → vasoconstriction → tissue death
Blood and endometrial debris (menses) lost through vagina
Dysmenorrhea
painful periods
Menorrhagia
heavy or prolonged periods
Amenorrhea
Absence of periods (primary or secondary)
Oligomenorrhea
light periods
explain the mechanism of action of the combined pill
low dose of oestrogen descrease FSH production, decreased development of the follicle and no ovulation.
progesterone makes the cervical mucus sperm unfriendly
decreased LH from the anterior pituitary
decreased GnRH from hypothalamus
decreased motility of Fallopian tube
what is the progesterone only pill
Low dose progestogen taken continuously
(e.g. either norethisterone or levonorgestrel).
Makes cervical mucus inhospitable to sperm.
Hinders implantation
through its effect on the endometrium and on the motility and secretions of the fallopian tubes.
Menstruation
often ceases initially but usually returns with prolonged use.
Main adverse effects
Breakthrough bleeding and irregular menses.
