MENSTRAL CYCLE

1. Hypothalamus releases GnRH2. GnRH tells Anterior Pituitary to release FSH3. FSH triggers follicle development, which causes the oocyte to swell and produce estrogen production4. Estrogen production also stimulates cells in the endometrium to increase cell divisions, thickening the lining of

the uterus in preparation for implantation.5. The increasing blood estrogen level also stimulates a surge of LH to be released by the Anterior Pituitary.6. Mid-cycle LH surge causes ovulation and the development of the Copus Luteum.7. Corpus Leteum produces Progesterone and Estrogen, which help maintain the Endometrium if pregnancy

occurs. You can see how the shape of the lining and progesterone curves are similar.8. Rise of Estrogen and Progesterone secreted by the Corpus Luteum acts as negative feedback to inhibit the

secretion of FSH/LH from the Anterior Pituitary.9. Progesterone also helps the uterus by quieting contractions and causing it to secrete key nutrients for

implantation.10. If implantation does not occur, hormone levels drop, causing the break down of the endometrium and initiating

meneces.