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Biology (BYB8) - Menstrual Cycle & Hormones Question watch

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    Ok how come oral contraceptives contain high level of oestrogen to prevent FSH to prevent follicle production, but at high levels of oestrogen in the menstrual cycle, it says FSH & LH are stimulated:

    During days 5-10 oestrogen levels rise slowly. Oestrogen inhibits release of FSH and LH, negative feedback. FSH levels decline and LH levels remain low. During days 10-14 there is a rapid rise in oestrogen levels. This has a positive feedback effect on FSH and LH. There is a surge of FSH and LH levels around 12-14.
    So how does this work with high levels of oestrogen preventing FSH production? Thanks :confused:
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    The contraceptives prevent ovulation by maintaining a consistently high level of oestrogen, which inhibits FSH and prevents the formation of Graafian follicles
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    Ok Thanks um one more question, it says

    Oestrogen inhibits release of FSH and LH, negative feedback. FSH levels decline and LH levels remain low.
    But I have some notes that say

    Rising oestrogen levels inhibit FSH and promote LH production
    Which way round is it? Does LH go up or down? lol Thanks!
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    yea that confuses me too! think basically FSH+LH stimulate oestrogen release, but when oestrogen gets too high it inhibits FSH+LH (dunno y tho!) then when LH suddenly rises at day 12, progesterone starts to be released instead of oestrogen. All a bit odd, think it actually said in one of my textbooks 'for reasons unknown, LH levels rise steeply on day 12'
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    Here's what I have:

    FSH promotes growth of Graafian follicle by causing follicle cells to divide. As the follicle gets larger it starts to secrete oestrogen. Oestrogen inhibits FSH to prevent the growth of more follicles. LH is stored in the pituitary gland as the follicle develops and secretes more oestrogen. The level of oestrogen reaches a peak - this triggers the pituitary to release its LH and ovulation occurs. The corpus luteum (what's left over of the Graafian follicle), which is nourished by LH, starts to secrete oestrogen and progesterone. These inhibit FSH and LH, so the corpus luteum starts to shrivel. The corpus luteum dies, so less oestrogen and progesterone are produced. Menstruation occurs. FSH and LH are no longer inhibited so start to be secreted again.

    Hope that helps
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    (Original post by madmazda86)
    Here's what I have:

    FSH promotes growth of Graafian follicle by causing follicle cells to divide. As the follicle gets larger it starts to secrete oestrogen. Oestrogen inhibits FSH to prevent the growth of more follicles. LH is stored in the pituitary gland as the follicle develops and secretes more oestrogen. The level of oestrogen reaches a peak - this triggers the pituitary to release its LH and ovulation occurs. The corpus luteum (what's left over of the Graafian follicle), which is nourished by LH, starts to secrete oestrogen and progesterone. These inhibit FSH and LH, so the corpus luteum starts to shrivel. The corpus luteum dies, so less oestrogen and progesterone are produced. Menstruation occurs. FSH and LH are no longer inhibited so start to be secreted again.

    Hope that helps
    Yes I think you're right! After some deduction from my notes and matching it with the textbook, I came to about the same conclusion as you did but that's a good useful summary which makes it a lot clearer, thank you very much!
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    i am also confused about this. i have notes saying that at low levels of oestrogen, LH and FSH are inhibited, but at high levels there is a positive feedback effect and their production is stimulated. and also progesterone inhibits FSH. gah. i think i'll stick with your version - madmazda86! it seems to make more sense! (i'm not surprised women have such bizarre moodswings - we are SO bloody complicated!)
 
 
 
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