Hey Guest! Check out the 3 MCAT Study Plan Options listed in the 'stickies' area at the top of the forums (BoomBoom, SN2ed, and MCATJelly). Let us know which you like best.

Also, we now offer a MCAT Test-Prep Exhibitions Forum where you can ask questions directly from the test-prep services.
SDN members see fewer ads and full resolution images. Join our non-profit community!

MCAT Biology

Discussion in 'MCAT Discussions' started by Jonkst, Aug 14, 2002.

  1. Jonkst

    Jonkst Senior Member 10+ Year Member

    209
    0
    Mar 20, 2002
    Florida
    Quick question about a Biology topic:
    Can anyone explain the menstrual cycle stuff. I have yet to find a source that explains it well.

    I have a feeling I'm going to get some interesting responses to this one...
     
  2. SDN Members don't see this ad. About the ads.
  3. rCubed

    rCubed taiko master 10+ Year Member

    416
    0
    Jul 14, 2002
    NY
    hmmm...let me take a stab at it

    first of all, remember...estrogen will stimulate gonadotropin releasing hormone (GnRH) which will stimulate LH and FSH

    however, estrogen and progesterone together inhibit GnRH which in turn inhibits LH and FSH


    ok, step by step:

    I. Follicular phase: FSH and LH are both being secreted, this is just after the woman has completed menstration. FSH and LH at this point develop ovarian follicles which in turn secrete estrogen, which will stimulate GnRH, which will stimulate even more LH and FSH

    II Ovulation: Now we have alot more LH which stimulate ovulation, or release of the egg from the ovary....

    III Luteal phase: now there's still all that LH and it acts on the follicle to develop it into the corpus luteum. the corpus luteum secretes estrogen and progesterone. both of these together will not only cause the endometrium to develop and vascularize, they'll make the LH and FSH secretions stop

    IV Menstration: this occurs only if there is no fertalization. the corpus luteum degenerates, thus no more progesterone and estrogen..so no more thick uterine lining, so menstration occurs. and since the corpus luteum just degenerated, and theres no more estrogen and progesterone together, LH and FSH can be secreted again



    hope that sort of helps, its a really short overview
     
  4. Jonkst

    Jonkst Senior Member 10+ Year Member

    209
    0
    Mar 20, 2002
    Florida
    Thanks rCubed. I appreciate it. Simple is fine; all I need for the MCAT anyway. "thus no more progesterone and estrogen" was all I needed to clear it up.

    Good luck to ya'
     
  5. limit

    limit Molesting my inner-child 10+ Year Member

    570
    1
    Jun 21, 2000
    New York City
    Why do you females have to be so complex?? :p
     
  6. rCubed

    rCubed taiko master 10+ Year Member

    416
    0
    Jul 14, 2002
    NY
    so the curve is in our favor:D
     

Share This Page