female reproductive

Question 1

define GnRH

Answer 1

• acts on ant pit to release gonadotropins

Question 2

define LH

Answer 2

act on ovary to increase estrogen/progesterone/inhibins

Question 3

define FSH

Answer 3

• act on ovary to increase estrogen/progesterone/inhibins

Question 4

define estrogen

Answer 4

• increases size of uterus, ovaries, vagina, breasts
• causes proliferation of endometrial stroma lining
• inhibits osteoblast activity
• increaes body protein and fat deposition
• increases sodium and water retention
• makes mucous thin and stringy which can help guide sperm

Question 5

define progesterone

Answer 5

• promotes secretory changes of uterus, and prepares uterus for implantation
• decreases uterine contractions
• decreases prostaglandin production
• secretes fluid in fallopian tubes
• increases secretory development of breast tissue
• opposite effect on cervical mucous (increases viscosity)

Question 6

describe the cell types and regulatory signals involved during steroidogenesis

Answer 6

• GnRH released in pusatile fashion 5-25 mins every 1-2 hours
• results in LH release around eery 90mins
• estrogen rises during follicular phase and peaks before dropping off at luteal phase
• progesterone rises during luteal phase and drops off at end.

Question 7

describe estrogen role in the follicular phase

Answer 7

• estrogen exerts a negative feedback regulation primarily at the level of the anterior pituitary and to some extent the hypothalamus

Question 8

Describe estrogens role at mid-cycle (just prior to ovulation)

Answer 8

• 36 hours of relatively high estrogen concentrations exert a POSITIVE FEEDBACK at the level of the anterior pituitary and to some extent the hypothalamus resulting in a gonadotropin surge

Question 9

describe progesterone and estrogens role at luteal phase

Answer 9

• progesterone and estrogen exert NEGATIVE feedback at the level of anterior pituitary and to some extend the hypothalamus
• result of neg. feedback is gonadotopin production declines which results in decline of steroid production

Question 10

describe Inhibin B roles in the female sexual cycle

Answer 10

• inhibin B is secreted by granuloma cells and exerts a negative feedback on anterior pituitary FSH secretion
• Just after ovulation, Inhibin B spikes to decrease FSH secretion

Question 11

describe inhibin A role in female sexual cycle

Answer 11

• inhibin A is high in the luteal phase and acts on the ant. pit. to inhibit gonadotropin secretion

Question 12

describe the transition to pregnancy

Answer 12

• If implantation occurs, the corpus luteum does NOT regress
• Instead, the placenta releases hCG
• hCG stimualtes ovarian steroidogenesis by binding to same LH receptor (becasue LH is decreasing during this time)
• Corpus luteum secretes relaxin to inhibit myometrial contractions

Question 13

describe the changes that occured after week 8

Answer 13

• the placenta can synthesize steroids and corpus luteum is no longer needed
• progesterone suppresses uterine contractions, inhibits prostaglandin production and impacts immune response
• estrogen stimulates uterine growth, thickens vaginal epithelium and growth/development of mammary epithelium

Question 14

describe key hormone changes observed during puberty

Answer 14

• pusatile release of GnRH at night between 8-13 years
• increase in estrogen synthesis and female development begins to take place
• menses begins around 13 years which indicates estrogen levels are high enough for endometrial growth

Question 15

describe key hormone changes observed during menopause

Answer 15

• beings around age 36 and symptoms of follicle loss begin around 51
• decrease in follicles results in decline of estradiol and inhibin causing a loss of negative feedback and elevated LH/FSH
• extragonadal estrogen exists, however huge decline in estrogen production = hot flashes, night sweats, loss of libido, loss of bone mass, increased risk of heart disease

Question 16

describe the two phases of ovarian cycle

Answer 16

• Follicular phase (day 1) is characterized by follicle development, endometrial proliferation
• follicular phase is followed by ovulation
• Luteal phase occurs after ovulation and characterized by corpus luteum formation, endometrial differentiation
• followed by menses

Question 17

describe steroid production in follicular phase

Answer 17

• estradiol production during follicular phase is regulated by the gonadotropins
• -> theca cells synthesize androstenedione in response to LH
• -> androstenedione is converted to estradiol in granulosa cells which is controlled by FSH

Question 18

describe follicular phase

Answer 18

• rise of gonadotropins with a particular emphasis on FSH increase
• granulosa cell proliferation causes secretion of follicular fluid (hormones)
• development of theca cells which forms a capsule around follicle and produce hormones
• Increase in steroid production (estradiol) regulated by LH and FSH
• extremely rapid follicle growth under control of steroids and gonadroptropins

Question 19

describe the regulation of rapid follicular growth

Answer 19

• Estradiol increases expression of FSH receptors resulting in increased granulosa cell sensitivity to FSH and more follicular secretion
• Estradiol and FSH increased expression of LH receptors on theca cells further increasing follicular secretion
• Rise in estradiol from the ovary and ris in LH from the anterior pituitary induce proliferation of the thecal cells resulting in an increase in follicular secretion

Question 20

describe the endometrial growth in follicular phase

Answer 20

• proliferation of uterine endometrium is regulated by estrogen
• -> proliferation of epithelial cells (4-7 days for complete)
• -> proliferation of stromal cells
• -> growth of endometrial glands
• -> blood vessel development
• -> mucus secretion

Question 21

describe ovulation

Answer 21

• Day 14, ovulation is stimulated by a surge of LH (required) and FSH
• LH stimulates rupture of the follicle by promoting a remodeling of the follicle through changes in gene expression patterns and cell signaling events

Question 22

describe the temperature changes during ovulation

Answer 22

• Basal body tempature (BBT) is the body temp at rest
• typically taken after waking up from 6 or more hours of sleep
• Progesterone is thermogenic and produces .5-.8 degree increase in BBT
• monitoring BBT can be used as an indicator of ovulation

Question 23

describe the corpus luteum

Answer 23

• corpus luteum forms during the luteal phase
• forms from thecal, granulosa, fibroblast, endothelial, and immune cells as well as lipids
• -> temporary endocrine gland and secretes estradiol and progesterone
• corpus luteum reaches a mature state around 7-8 days following ovulation

Question 24

describe steroid production in luteal phase

Answer 24

• Increases in estradiol and progesterone production during luteal phase
• -> luteinized theca cells synthesize androstenedione in response to LH
• -> androstenedione is converted to estradiol in the luteninized granulosa cells which is controled by LH
• Also there is an upregulation of genes required for progesterone synthesis also under the control of LH

Question 25

describe the endometrial differentiation in luteal phase

Answer 25

• during luteal phase, differentiation and secretory development of uterine endometrium is regulated primarily by progesterone
• Key endometrial changes:
• -> increased complexity of vascular and glandular structures
• -> accumualtion of substances in glands
• -> deposition of lipids and glycogen in stromal cells
• -> increased blood supply

Question 26

describe the negative feedback mechanism in luteal phase

Answer 26

• rise in steroids (progesterone and inhibins (inhibin A) exert negative feedback at the level of anterior pituitary
• as a result gonadotropin production declines which results in decline of steroid production

Question 27

define involution

Answer 27

• twelve days following ovulation the corpus luteum begins to regress (involution) and becomes corpus albicans
• steroid production decliens with regression of corpus luteum

Question 28

describe menstrual phase

Answer 28

• declines in estrogen and progesterone production results in:
• -> the release of proteolytic enzymes that cause lysis of tissue
• -> increase of prostaglandin production that increases myometrial contractions
• with the decrease in gonadal steroid production, negative feedback inhibiton on the HPG axis is relieved and gonadotropin (LH, FSH) production begins to rise