Physio 7 Flashcards
follicular phase
FSH stimulates development of follicles. (FSH and rising estradiol)
estradiol promotes proliferation of the endometrium and primes the uterus for progesterone actions
ovarian cycle
a series of hormone-mediated changes in the ovaries culminating in the monthly production of a viable ovum in women of reproductive age
ovulatory phase
LH surge causes rupture of the Graafian follicle. (LH Surge)
luteal phase
LH converts the ruptured follicle to a corpus luteum. (LH, high progesterone and some estradiol) Progesterone converts proliverative uterus to a secretory uterus
what happens to corpus luteum if no fertilization occurs?
degenerates and forms a corpus albicans. (low estrogen and progesterone)
primordial follicle
increases in size during the ovarian cycle. contains the ovum, thecal, and granulosa cells
proliferative phase
11 days. thickness of endometrium increases. dominated by estrogens
secretory phase
12 days. dominated by progesterone. promotes accumulation of glycogen, increased glandular secretions, and increased vascularity
menstrual phase
associated with prostaglandin-mediated vasoconstriction of spiral arteries and local ischemic injury/inflammation. associated with regression of the corpus luteum (5 days)
hormonal regulation of the menstrual cycle
HnRH stimulates release of FSH and LH, and estrogen synth by follicles has negative feedback. In late follicular phase, blood estradiol reaches a high level that initiates positive feedback and a surge in LH and FSH, provoking ovulation. luteal phase shows negative feedback. Estradiol, progesterone, and inhibin produced by corpus luteum have negative feedback on gonadotropin release
pulsatile release of GnRH and LH
estrogens in late follicular phase sensitize the anterior pituitary gonadotrophs to stim by GnRH. this produces a mid cycle surge of LH release necessary for the rupture of the growing follicle and ovulation
GnRH
secreted by neurons in the arcuate nucleus and preoptic area of hypothal. reaches gonadotrophs in pituitary to increase synth and secretion of FSH and LH
regulation of gonadotropin secretion
GnRH binds to a G protein coupled receptor on the gonadotroph membrane. triggers IP3/DAG pathway. causes gonadotrophs to make and release FSH and LH
estrogen and progesterone metabolism
derived from cholesterol. steroid hormones. bind to albumin and sex hormone-binding globulins in serum. estrogen inactivated in liver through conjugation, progesterone rapidly degraded in liver to steroids. both excreted in urine.
2 cell, 2 gonadotropin model of steroid synth (follicular phase)
during follicular phase, major product of follicle is estradiol. during luteal phase, major product of corpus luteum is progestins. LH primes theca cell to convert cholesterol to androstenedione. Theca cell cant make estradiol due to lack of aromatase. Androstenedione diffuses to granulosa cell where aromatase has been stimulated by FSH. here, estradiol is made.
2 cell, 2 gonadotropin model of steroid synth (luteal phase)
corpus luteum makes LDL available to granulosa-lutein cells. theca-lutein and granulosa-lutein cells can both make progesterone. for production of 17-a-OH progesterone, some of the progesterone diffuses into the theca-lutein cell which has the hydroxylase needed for conversion of progesterone
estrogen effects
proliferation of uterine endometrial stroma and development of endometrial glands. prolif and development of mucosal lining of fallopian tubes. stim of bone growth through osteoclast inhibition. increased fat deposition in subcutaneous tissue. during follicular phase, induce endometrial gene products that promote growth and prime the uterus for progesterone through inducing progesterone receptors
progesterone effects
secretory changes in the uterine endometrium. decreased freq and intensity of uterine contractions. increased fallopian tube secretions. during luteal phase, induces genes that convert uterus to a secretory type.
puberty and the phases
the transition to cyclic female reproductive function. thelarche: breast development. Adrenarche: increased secretion of adrenal androgens. Menarche: menstrual cycles begin. estrogen promotes rapid bone growth, deposotion of fat, and ductile growth in boobs. progesterone promotes development of lobules and aveoli in boobs
negative feedback before puberty
release of gonadotropins is low before puberty due to the low amounts of sex steroids. negative feedback sensitivity is high. GnRH eventually begins to pulse at night then during the day
menopause
cyclic reproductive function and menstruation cease. usually 51-52 years old. no remaining ovarian follicles, which causes decrease in steroid hormones level of circulating sex steroids decrease. circulating gonadotropins increase due to lack of estrogen (loss of negative feedback) a variety of physical and mental changes occur
estrone
made by muscle and adipose tissue. provides a postmenopausal source of estrogen. no where near as potent as estradiol.
why are women at risk for osteoporosis and fractures after menopause?
estrogens prevent bone loss. a healthy diet of vitamin D and calcium is needed to preserve bone mass, as well as weight bearing exercise
