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Flashcards in Endocrine regulation of Female Reproductive tract Deck (17)
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what are the different phases of the menstrual cycle, in order

follicular(proliferative) phase, ovulation and luteal(secretory) phase


how long does the follicular and luteal phases last

follicular = variable, usually 14 days, +/- 7days
luteal = more constant, 14 days
(around 28days total)


describe what happens at the start of the menstrual cycle

FSH stimulates growth of ovarian follicles, associated with increase in oestrogen levels
(follicular phase)


describe what happens as a result of the initial rising oestrogen levels in the follicular phase

exert negative feedback on hypothalamus/pituitary, temporarily lowering FSH levels


describe what happens when oestrogen levels reach a certain conc. threshold in the follicular phase

exerts positive feedback regulation resulting in an increase in FSH levels and the LH 'surge'


what does the LH surge lead to and what does it regulate

leads to ovulation and regulates formation of corpus luteum and progesterone production and secretion


what effect does increased progesterone in the luteal phase have

decreases LH secretion by influencing GnRH pulsatility


what does a follicle consist of

an oocyte surrounded by follicular cells(granulosa and theca cells)


what does follicular growth involve

increase in number of follicular cells(not oocytes), and accumulation of follicular fluid both resulting in increased diameter and overall size of follicle
(oocyte remains dormant)


what effect does oestrogen and progesterone have on the endometrium

endometrium thickens due to oestrogen
endometrium becomes secretory tissue due to progesterone


although onset of ovulation is variable between women and from one cycle to another, describe how timing of ovulation can be predicted

can be predicted with reasonable accuracy with LH surge, the surge precedes ovulation by 34-36 hours


what is the threshold of oestrogen required for ovulation to occur

200pg/ml, needed for increased GnRH pulsatility and LH surge, therefore ovulation


describe how LH stimulates increase in progesterone production by the corpus luteum

LH stimulates angiogenesis(ensures efficient delivery of cholesterol for progesterone synthesis), also stimulates enzymes in conversion of cholesterol to progesterone


what happens to granulosa and theca cells in the luteal phase

transform to luteal cells as part of the corpus luteum


what are the recognised functions of oestrogens

increase thickness of vaginal wall, regulate LH surge, reduce vaginal pH by increasing lactic acid production, decrease viscosity of cervical mucous to facilitate sperm penetration


what are the recognised function of progesterone's

maintain endometrium thickness, responsible for infertile thick mucus, relaxes the myometrium, functional progesterone withdrawal thought to regulate birth


what is the sperms ability to penetrate the cervical mucus regulated by

thickness of mucus, motility of sperm, interaction with reactive oxygen species, interaction with mucins