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Anatomy & Physiology II Final

Terms in this set (31)

Female Hormonal interaction during ovarian cycle.
1. GnRH stimulates FSH and LH secretion
2. FSH and LH stimulate follicles to grow, mature, and secrete sex hormones
- FSH stimulates granulosa cells to release ___________, and LH prods thecal cells to produce ___________, which granulosa converts to ____________
3. Negative feedback inhibits ____________ release
- Increasing levels of plasma estrogen levels exert negative feedback inhibition on FSH and LH release
- Inhibin from granulosa cells also inhibits _______ release
- Only dominant follicle can withstand this dip
- Other developing follicles deteriorate
4. Positive feedback stimulates gonadotropin release
- Estrogen levels continue to rise as a result of continued release by dominant follicle
- When levels reach a critical high value, a brief positive feedback occurs on brain and anterior pituitary
- Triggers LH surge
5. LH surge triggers ovulation and formation of the corpus luteum
- High estrogen levels trigger release of stored LH, and some FSH, by anterior pituitary at midcycle
- Surge triggers ovulation
- LH surge triggers primary oocyte to complete meiosis I to become secondary oocyte
- Secondary oocyte then enters meiosis II, continuing on to metaphase II
- Shortly after ovulation:
• Estrogen levels decline
• LH transforms ruptured follicle into corpus luteum
• LH stimulates corpus luteum to secrete progesterone and some estrogen almost immediately
• Progesterone helps maintain stratum functionalis
• Maintains pregnancy, if it occurs
6. Negative feedback inhibits LH and FSH release
- Negative feedback from rising plasma progesterone and estrogen levels inhibits LH and FSH release
- Inhibin, from corpus luteum and granulosa cells, enhances inhibitory effect
- Declining LH ends luteal activity and inhibits follicle developmen
- If no fertilization occurs:
• Corpus luteum degenerates when LH levels start to fall
• Causes a sharp decrease in estrogen and progesterone, which in turn ends blockage of FSH and LH secretion, causing cycle to start all over again
- Oocyte is actually activated 12 months prior to ovulation but matures 14 days before ovulation