Hormones affecting reproduction

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Hormones affecting reproduction

  1. 1. Endocrine SystemPart 5: Reproduction
  2. 2. Reproductive System Male FemaleGonad Testes OvaryGamete Sperm Ovum (egg)Hormones Androgens: Estrogen testosterone, progesterone androsterone
  3. 3. Male Anatomy Fig. 46.8
  4. 4. Cells of the Testes Leydig interstitial cells synthesize hormones (androgens) Sertoli cells synthesize sperm (spermatogenesis)
  5. 5. Male Reproductive Hormones:Androgens androsterone testosterone
  6. 6. Male Reproductive Hormones:Androgens both hormones are released from testes
  7. 7. Androgen: Testosterone Steroid hormone Develops male primary and secondary sexual characteristics
  8. 8. Primary Sexual Characteristics Associated with the reproductive system Development of vas deferens, external reproductive structures Stimulate spermatogenesis: sperm production in sertoli cells (lifetime process)
  9. 9. Secondary Sexual Characteristics Not directly related to the reproductive system Develops characteristics at puberty  deepening of voice  facial and pubic hair  muscle growth  increased secretion of body oils (associated with body odour)
  10. 10. Male Reproductive Hormones Hypothalamus 1. Hypothalamus: Gonatropin GnRH releasing hormone (GnRH) Anterior pituitary 2. Anterior Pituitary: Gonadotropic hormones FSH & LHFSH LH 3. Sertoli cells: FSH stimulates spermatogenesis testes 4. Leydig cells: LH stimulates Sertoli Leydig hormone (androgen) secretion cells cells 5. Androgen testosterone affects primary & secondary sexual testosterone characteristics sperm production
  11. 11. Gonadotropic Hormones Two types:  Follicle stimulating hormone (FSH)  Luteinizing hormone (LH) Peptide hormones Present in both male and female
  12. 12. Gonadotropins in Males FSH: act on Sertoli cells to increase spermatogenesis (nontropic) LH: stimulate Leydig cells to make androgens (tropic) Image Source: http://www.andrologyaustralia.org/images/pageContentImages/MI_Image_Jul2005_04HormonalLinks.jpg
  13. 13. Male Reproductive Hormone:Neuroendocrine pathway - nontropic Location Hormone Hypothalamus Gonadotropin-Releasing Hormone (GnRH) Anterior Pituitary Gonadotropins: Follicle-stimulating hormone (FSH) Effect: Sertoli Spermatogenesis cells
  14. 14. Male Reproductive Hormone:Neuroendocrine pathway - tropic Location Hormone Hypothalamus Gonadotropin-Releasing Hormone (GnRH) Anterior Pituitary Gonadotropins: Lutenizing hormone (LH) Testes: Leydig Androgens: testosterone cells Effect Primary and secondary sexual characteristics
  15. 15. Male Reproductive Hormonal Control hypothalamus GnRH pituitaryFSH LH testes Sertoli Leydig cells cells testosterone sperm production Fig. 46.14
  16. 16. Negative Feedback Testosterone negatively feedback to the hypothalamus and pituitary to decrease the production of GnRH and LH
  17. 17. Female Reproductive System comparatively more complicated than male reproductive system monthly cycle until menopause (~12 to 50 yrs) one ovum produced per germ cell
  18. 18. Female Anatomy Fig. 46.9
  19. 19. Female Reproductive Hormones estrogen progesterone
  20. 20. Female Reproductive Hormones both produced in the ovaries
  21. 21. Estrogens Female sex hormones Estriol Three compounds  Estradiol is predominant Develops secondary sexual characteristics Estradiol  Breast development  Wider hips  Fat deposition Estrone Image Sources: Wikipedia, http://en.wikipedia.org/wiki/Estrogen, http://trollydolly.us/wp-content/uploads/2009/04/estrogen-cartoon.gif
  22. 22. Ovary Follicle Cells primary oocyte: egg that can be fertilized by sperm granulosa cells: provide nutrients for primary oocyte
  23. 23. Ovarian Cycle Regulation:Neuroendocrine pathwayLocation HormoneHypothalamus Gonadotropin-Releasing Hormone (GnRH)Anterior Pituitary Gonadotropins: Follicle-stimulating hormone (FSH) Lutenizing hormone (LH)Ovaries: Follicle & EstrogenCorpus Luteum Progesterone
  24. 24. Gonadotropin-ReleasingHormone (GnRH) GnRH levels not shown in graph or right but correlates to the rise in LH/FSH levels Released in slow waves during follicular phase Rate of release is increased (peaked) when approaching ovulation Rate decreases greatly during luteal phase
  25. 25. Gonadotropins in Females FSH:  Stimulates growth of follicle (maturation) in follicular phase LH:  lutenizes the follicle into the corpus luteum  Induces ovulation  Matures the corpus luteum in luteal phase
  26. 26. Ovarian Cycle Follicular phase  Growth of several follicles but only one matures while others disintegrate  Egg in follicle enlarges  Coat of follicle thickens  Fluid-filled cavity inside follicle develops and bulges Ovulation  Follicle and wall of ovary rupture  Egg is released Luteal phase  Follicular tissue develops into corpus luteum  Corpus luteum secretes female hormones
  27. 27. Ovulation Fig. 46.13b
  28. 28. Ovulation EGG CELLFig. 46. 10
  29. 29. Female Reproductive HormoneControl hypothalamus GnRH pituitary 1 2 FSH LH ovaries corpus follicle luteum estrogen progesterone some estrogen ovulation
  30. 30. Progesterone Corpus luteum secretes progesterone (and some estrogens) Correlates to thickening of endometrium  in order to accept fertilized egg and enable implantation and growth Image Source: Wikipedia, http://en.wikipedia.org/wiki/Progesterone
  31. 31. Progesterone If no implantation then corpus luteum disintegrates  progesterone isn’t secreted Decreased progesterone levels leads to:  stop of endometrium growth  endometrium breaks down (menstruation) Image Source: Wikipedia, http://en.wikipedia.org/wiki/Progesterone
  32. 32. Menstrual Cycle Day 1 = first day of menstruation Menstrual flow phase  sloughing of endometrial lining  menstrual bleeding Proliferative phase  endometrium regenerates and thickens Secretory phase  endometrium continues to thicken  becomes more vascularized (blood vessels)  develops glands to secrete fluid rich in glycogen
  33. 33. Female Reproductive HormoneControl hypothalamus GnRH pituitary 1 2 FSH LH ovaries corpus follicle luteum estrogen progesterone some estrogen ovulation
  34. 34. Follicle Granulosa cells of follicle secretes estrogen
  35. 35. Estrogen Regulation: High levels High estrogen: Positive feedback on LH & FSH by stimulating GnRH Estrogen surge from follicle during day 12-14  LH & FSH surge  Results in ovulation
  36. 36. Estrogen Regulation Also responsible for the early thickening of the endometrium in the proliferative phase
  37. 37. Estrogen Regulation: Low levels Estrogen secreted at low levels during most of the cycle Negative feedback on GnRH, LH & FSH
  38. 38. Estrogen Regulation Corpus luteum secretes estrogen and progesterone Both act together to negatively feedback on GnRH, LH & FSH Prevents ovulation
  39. 39. Dual Role of Estrogen Low estrogen concentration  negative feedback High estrogen concentration  positive feedback http://www.sumanasinc.com/webcontent/animations/content/ovarianuterine.html
  40. 40. Female Reproductive HormoneControl Day 12-14 when hypothalamus estrogen levels surge GnRH Day 12-14 when pituitary estrogen levels surge 1 2 FSH LH ovaries corpus follicle luteum estrogen progesterone some estrogen ovulation
  41. 41. Overview ofFemaleReproductiveCycles Fig. 46.15
  42. 42. Hormonal Controlin Follicular phase Immature follicles have receptors for FSH but not LH FSH stimulate follicular growth Granulosa cells of the growing follicles secrete estrogen Low levels of estrogen negatively feeds back on LH and FSH Fig. 46.15
  43. 43. Hormonal Controlnear ovulation Estrogen surge  Positive feedback on LH & FSH by stimulating GnRH Mature follicle have receptors for LH LH induces ovulation Estrogen also stimulates thickening of endometrium Fig. 46.15
  44. 44. Hormonal Controlin Luteal Phase LH lutenizes remaining follicular tissue into corpus luteum Corpus luteum secretes estrogen and progesterone Both act together to negatively feedback on GnRH, LH & FSH Fig. 46.15
  45. 45. Hormonal Controlin Luteal Phase Corpus luteum disintegrates Sharp decline in estrogen & progesterone Negative feedback removed  Secretion of GnRH, LH & FSH begins Disintegration of endometrium Fig. 46.15
  46. 46. Menopause Occur around age 46-54 Ovaries lose responsiveness to gonadotropins  Decline in estrogen production  Cessation of ovulation and menstruation

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