Female Reproductive Hormones

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Endocrinology Mind Map on Female Reproductive Hormones, created by maisie_oj on 22/04/2013.
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Mind Map by maisie_oj, updated more than 1 year ago
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Created by maisie_oj over 11 years ago
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Resource summary

Female Reproductive Hormones
  1. Function of the Ovaries
    1. Production of female gametes (ova)
      1. Production of female sex hormones - oestrogens and progesterone
      2. The Ovarian Cycle
        1. Primordial follicles made up of an oocyte surrounded by a single cell layer
          1. 400 000 present in each ovary at menarche (first period)
            1. After follicular selection the cells divide to form 2 layers - outer stromal cells and inner granulosa cell layer
              1. A layer of theca cells (theca externa and theca interna) develops between the 2 layers and oocyte is surrounded by zona pellucida
                1. Follicular antrum develops and fills with follicular fluid
                  1. Mature oocyte is suspended in the follicular fluid and attached to the granulosa layer by a stalk
                    1. During ovulation the follicle ruptures and releases the oocyte
                      1. The antrum fills with blood, forming a corpus haemmorrhagicum
                        1. Develops into the corpus luteum
                          1. Corpus luteum regression forms the corpus albicans
            2. Oestrogens are the main secretory product of the developing follicle
              1. Secreted by theca and granulosa cells
                1. Theca cells release testosterone which is converted to oestradiol by granulosa cells
              2. Progesterone is the main secretory product of the corpus luteum
              3. Ovarian Steroidogenesis
                1. Cholesterol
                  1. Pregnenolone
                    1. Progesterone
                      1. 17-alpha-hydroxyprogesterone
                        1. Androstenedione
                      2. 17-alpha-hydroxypregnenolone
                        1. DHEA
                          1. Androstenedione
                            1. Oestrone (via Aromatase)
                              1. In
                              2. Testosterone
                                1. 17-beta-oestradiol (via Aromatase)
                                  1. equilibrium
                    2. Control of Steroidogenesis
                      1. GnRH stimulates release of LH and FSH (low-pulse requency for FSH, high pulse-rate for LH)
                        1. LH increases testosterone production
                          1. Conversion to oestradiol in granulosa cells
                            1. Oestradiol inhibits gonadotrophs and GnRH
                          2. FSH increases oestradiol production in granulosa cells
                        2. Action of Oestrogens
                          1. Development and maintenance of secondary sex characteristics
                            1. Stimulation of breast development during puberty/pregnancy
                              1. Maintain structure and secretory function of vaginal mucosa
                                1. Promote uterine development (stimulate endometrial cell proliferation)
                                  1. Increase libido
                                    1. Important for bone health
                                    2. Actions of Progesterone
                                      1. Maintenance of pregnancy
                                        1. Normally inhibits the proliferative effects of oestrogens
                                          1. Facilitates ovulation
                                          2. Ovarian Peptide Hormones
                                            1. Inhibin
                                              1. Secreted by granulosa and theca cells of developing follicle
                                                1. Increases FSH release
                                                2. Relaxin
                                                  1. Stimulates follicular development and oocyte maturation
                                                    1. May have a role in implantation
                                                  2. Activin
                                                    1. Produced by ovary and endometrium
                                                      1. May have a role in endometrial development
                                                  3. Menstrual Cycle
                                                    1. Generallly 28 days
                                                      1. 2 phases
                                                        1. Follicular phase
                                                          1. Variable length
                                                          2. Luteal phase
                                                            1. Always 14 days
                                                          3. Ovulation occurs halfway through the cycle - between the phases
                                                            1. LH and FSH remain at a low level and peak at ovulation. LH levels are higher than FSH levels
                                                              1. Oestradiol levels increase until a peak at ovulation, second smaller, less steep peak starts at ~day 17
                                                                1. Progesterone increases rapidly immediately after ovulation, plateaus between days 17-25 before a sharp decrease to a low level
                                                                  1. The endometrium grows between days 5-14 and breaks down between days 1-5
                                                                    1. Mean body temperature increases during ovulation
                                                                    2. Ovulation
                                                                      1. Occurs on day 14
                                                                        1. Preceded by an increase in oestrogen
                                                                          1. Triggers a GnRH/LH surge
                                                                            1. LH surge stimulates ovulation
                                                                              1. Increases synthesis of COX2 - involved in prostaglandin synthesis (especially PGEs)
                                                                                1. Bind to EP2 receptor - increases cAMP
                                                                                  1. COX2/EP2 knockout mice can't ovulate
                                                                                2. Acts on GnRH secreting neurones in the hypothalamus
                                                                                  1. Not a direct action of oestrogen - mediated by oestrogen-responsive neurones
                                                                                    1. Use kisspeptin as a transmitter
                                                                                      1. Kisspeptin stimulates GnRH release
                                                                              2. Positive feedback
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