HORMONES!

1. HORMONES!

2. Hormones Involved in Reproduction - MALES ● Androgens: produced by Leydig cells in testes -ex: testosterone ● GnRH: from hypothalamus; regulates release of FSH and LH from pituitary ● FSH: acts on Sertoli cells of seminiferous tubules to promote spermatogenesis ● LH: stimulates Leydig cells to produce testosterone (stimulates sperm production)

4. *PRIMARY SEX CHARACTERISTICS (associated with the reproductive system: -development of internal and external reproductive organs -sperm production

5. * SECONDARY SEX CHARACTERISTICS : -deepening of voice -distribution of facial & pubic hair -muscle growth

6. Hormones Involved in Reproduction - FEMALES ● Estrogen: produced by growing follicle ● Progesterone: inhibits release of FSH & maintains blood vessels in uterine lining ● GnRH: from hypothalamus; regulates release of FSH and LH from pituitary ● FSH: acts on follicle in ovary to continue oogenesis ● LH: stimulates follicle to rupture (causes ovulation)

7. Hormones Involved in Reproduction - FEMALES ● 2 parallel cycles controlled by these hormones 1) OVARIAN CYCLE = changes that occur in ovaries 2) MENSTRUAL CYCLE = changes that occur in uterus

8. Ovarian Cycle (3 phases): • Follicular phase: time during which several follicles in ovaries begin to grow • Cycle begins with release of GnRH stimulates the pituitary to secretes FSH & LH • FSH stimulates the follicle to grow • Growing follicle produces estrogen (Follicular phase)

9. Ovarian Cycle: • Ovulatory phase: follicle & adjacent wall of ovary rupture, releasing the egg (2° oocyte) • Steep increase inestrogen increases release of GnRH • GnRH increases secretion of FSH & LH (LH surge!) • Follicle has more LH receptors & LH induces final maturation & ovulation

10. Ovarian Cycle: 3)Luteal phase: the remaining follicular tissue in ovary after ovulation becomes the CORPUS LUTEUM (C.L.) which is endocrine tissue that secretes hormones • LH stimulates transformation of follicular tissue to C.L. • C.L. secretes estrogen & progesterone • Combination of these hormones exerts negative feedback on hypothalamus & pituitary (Luteal phase)

12. Near the end of the Luteal Phase, C.L. disintegrates • Decreases estrogen & progesterone which “liberate” hypothalamus & pituitary from inhibitor effects • GnRH can now be secreted (then FSH & LH) **The cycle begins again!**

14. Menstrual cycle also occurs in 3 phases: 1) Menstrual flow phase (3-5 days): time during which endometrium is being shed from uterus (1st day of menstruation =Day 1 of both cycles)

15. Menstrual cycle: 2) Proliferative phase (1-2 weeks): involves regeneration & thickening of endometrium • Caused by the estrogen secreted from the follicles • After ovulation, secreted estrogen & progesterone stimulate continued development & maintenance of the endometrium

16. Menstrual cycle: 3) Secretory phase (2 weeks): endometrium continues to thicken (due to estrogen & progesterone); it becomes more vascularized & develops glands which secrete a glycogen rich fluid which serves as nutritional fluid for the embryo

17. IF embryo does NOT implant in uterine lining by the end of this phase, a new menstrual flow phase begins • Disintegration of the C.L. reduces blood flow to the endometrium  the endometrium breaks down & passes out of the uterus (back to Menstrual Flow Phase) • IF embryo is present, it secretes HCG which maintains estrogen & progest. secretion by the C.L. so the endometrium is maintained

20. *primary sex characteristics: associated with the reproductive system -development of internal and external reproductive organs -egg production

21. *secondary sex characteristics: -increases fat deposition in breasts & hips -increases water retention -affects calcium metabolism -stimulates breast development

22. MENOPAUSE Menopause: cessation of ovulation and menstruation -between ages of 46 and 54 -ovaries lose their responsiveness to FSH/LH -results from decline in production of estrogens