Question | Answer |
LH and FSH stimulation in ovaries | steriodogenesis in ovarian follicle and corpus luteum, follicular development beyond antral stage, ovulation, lutenization |
Estrogen | has both postitve and negative feedback effects on FSH and LH, causes maturation and maintenance of fallopian tubes, uterus, cervix, and vagina; causes development of secondary sex characteristics, upregulates estrogen, LH, and progesteron receptors |
estrogen | causes proliferation and development of ovarian granulosa cells, mantians pregnancy, stimulates prolactin secretion, and lowers uterine threshold to contractile stimuli |
progesterone | has a negative feedback effects on FSH and LH secretion during th luteal phase |
progesterone | mantains pregnancy, raises uterine threshold to contractile stimuli, participates in developmnet of the breast |
follicular phase | Day 1-14 |
follicular phase | a primordial follicle develops to the graafian stage with atresia of neighboring follicles, |
follicular phase | LH and FSH receptors are up regulated in theca and granulosa cells, estradiol levels increase and cause proliferation of the uterus, FSH and LH levels are suppressed by negative feedback of estradiol on anterior ptiuitary, Pogesterone levels are low |
ovulation | day 15, always occurs 14 days before menses |
ovulation | a burst of eastradiol synthesis at the end of the folliculat phase has a positive feedback effect on the secretion of FSH and LH, ovulation occurs as a result of the estrogen induced LH surge |
ovulation | estrogen levels decrease just after ovulation, cervical mucus increases |
luteal phase | days 15-28 |
luteal phase | corpus luteum develops and synthesizes estrogen and progesterone, vascularity and secretory activity of the endometrium increases, body temperature increases |
fertilization | the corpus luteum is rescued from regression by HCG which is produced by the placenta |
1st trimester | corpus luteum is responsible for the production of estradiol and progesterone, peak levels of HCG occur at week 9 and then declines |
second and third trimester | progesterone is produced by the placenta, estrogens are produced by fetal adrenal gland and placental modification, human placental lactogen is produced throughout pregnancy |
prolactin | levels increase steadily during pregnancy, lactation does not occur during pregnancy becuase estrogen and progesterone block the action of prolactin on the breast |
ovulation during lactation | inhibits GnRH secretion, inhibits action of GnRH on anterior pituitary, antagonizes actions of LH and FSH on ovaries |