Ovarian/ Menstrual Cycle Pregnant Vs. Nonpregnant

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Ovarian/ Menstrual Cycle Pregnant Vs. Nonpregnant
2013-02-01 07:45:10
BIO 220

Chapter 46
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  1. Ovarian Cycle: Not pregnant
    • a.       If no fertilization:
    •                                                                           i.      Toward the end of the cycle, if fertilization did not occur, high progesterone turns off LHà corpus luteum dies and becomes a corpa albicantia
    • 1.      If the corpus luteum dies, there is no more production of progesterone and progesterone levels decrease (consequence seen in menstrual cycle)
  2. Ovarian Cycle: Pregnant
    • a.       If there was a pregnancy:
    •                                                                           i.      Toward the end of the cycle, high progesterone turns off LH
    • 1.      But now we have an embryo that is approximately two weeks old and the embryo is secreting HCG (human chorionic gonadotropins)
    • a.      It takes up where LH left off
    • b.      It maintains the corpus luteum during the first trimester
    • c.       Keeps the corpus luteum producing and secreting progesterone DURING THE FIRST TRIMESTER
    • d.      HCG levels are responsible for morning sickness, which occur at first trimester
    •                                                                                                                                                   i.      HCG found in urine and blood for pregnancy tests
    • 2.      Corpus luteum dies at end of first trimester, but PROGESTERONE LEVELS DON’T DECREASE
    • a.      It’s being produced and secreted by the placenta
    •                                                                                                                                                   i.      It takes about the first 2-3 months for the placentum to mature and produce hormones
    • b.      If progesterone levels decrease too soon, it can result in a spontaneous abortion
    • b.      Egg is caught up in fallopian tubes after it is dispelled
  3. Menstrual Cycle: Not pregnant
    • a.       If not pregnant:
    •                                                                           i.      Toward end of cycle, LH goes away, which was maintaining the corpus luteum, keeping it producing progesterone
    • 1.      Without LH, corpus luteum dies and progesterone levels drop, causing the progesterone levels to cause menses of the endometrium
  4. Menstrual Cycle: If pregnant
    • a.       If pregnant:
    •                                                                           i.      LH still disappears because high estrogen levels cause it to turn it off; but it has no effect because HCG maintains the corpus luteum and keeps it secreting progesterone during the first trimester
    • 1.      After the first trimester, HCG disappear but progesterone levels don’t decrease because the placenta is producing progesterone