Physiology/Hormones Flashcards
Menarche
first menstrual cycle; average 12.5 yo
Menopause
when menstrual cycle stops; typically 45-55 yo
Length of menstrual cycle
typically 28-35 days
greater variation in first years after menarche and last years before menopause
Define day 1 of menstrual cycle
day that menses begins
Phases of ovarian cycle and what is occurring?
- Follicular phase - development of ovarian follicles; estrogen release
- Ovulation - release of mature ovum
- Luteal phase - formation of corpus luteum; progesterone release
Phases of uterine cycle and what is occurring?
- menstrual phase - bleeding
- proliferative phase - growing of uterus lining (estrogen)
- secretory phase - corpus luteum and continued growth preparing for implantation (progesterone)
Hypothalamic control of ovarian hormones
releases GnRH causes LH and FSH release in anterior pituitary
Pulsative GnRH release:
faster freq = LH
slower freq = FSH
Function of intraovarian factors
each month just before menses the ovary selects several eggs from the pool of quiescent eggs to mature; this egg is dominant follicle and develops FSH receptors
immature but activated eggs involute
makes it possible for oocyte production to continue throughout woman’s reproductive life
Effects of LH surge during ovarian cycle
finishes maturation of follicle and weakens follicular wall for expulsion from ovary = ovulation
Primary secretion of corpus luteum
progesterone
Function of FSH
matures follicle
Primary secretion of follicles
estrogen
What is necessary stimulant to maintain corpus luteum?
LH; when LH levels drop then progesterone drops and corpus luteum degrades
Without adequate progesterone, what happens to uterus?
uterine lining cannot be maintained and menses occurs
What happens to corpus luteum if egg is fertilized?
hCG maintains the corpus luteum until the placenta is developed to an extent that it can take over progesterone function and prevent menses
How does estrogen affect LH release?
low estrogen levels suppress LH
high estrogen level mid-cycle causes LH surge
What are other peptide hormones secreted by ovary?
Inhibin A, Inhibin B, and Activin
Inhibin B important in suppressing FSH and used as marker of ovarian reserve
What causes shedding off of endometrium?
falling progesterone levels and degradation of corpus luteum
Menorrhagia
routine occurrence of abnormally heavy (≥ 81 ml) and /or prolonged menstrual period (≥ 7 days)
High levels of ______ allow corpus luteum to persist in ovary.
hCG
