Understanding Male and Female Reproductive Hormones

1. Reproductive Hormones http://www.youtube.com/watch?v=WGJsrGmWeKE&feature=related

2. Male Reproductive Hormones • androsterone • testosterone

3. (Urinary bladder) Seminal vesicle (Rectum) (Pubic bone) Erectile tissue of penis Vas deferens Ejaculatory duct Prostate gland Urethra Bulbourethral gland Glans penis Vas deferens Epididymis Testis Prepuce Scrotum

4. (Urinarybladder) Seminal vesicle (behind bladder) Prostate gland Bulbourethral gland Urethra Erectile tissue of penis Scrotum Vas deferens Epididymis Glans penis Testis

5. Male Reproductive Hormones • both hormones are released from testes

6. Testes Cells • Leydig interstitial cells synthesize hormones (between seminiferous tubules) • Sertoli cells synthesize sperm within seminiferous tubules

7. Testosterone Role • stimulates spermatogenesis (production of mature sperm cells) – life time process • develops male characteristics at puberty

8. Gonadotropic Hormones • gonadotropic hormones regulate gonad development (male and female) • produced in the anterior pituitary; released upon hypothalamus signal • follicle stimulating hormone (FSH) • luteinizing hormone (LH)

9. Male Gonad Development • Hypothalamus secretes gonadotropin-releasing hormone (GnRH) • Anterior pituitary gland releases FSH & LH • FSH stimulates Sertoli cells to form mature sperm • LH stimulates Leydig cells to secrete testosterone

10. Male Gonad Development Role of testosterone: • promotes Sertoli cell activity - increases sperm cell production • negative feedback on hypothalamus - inhibits the hypothalamus by decreasing the secretion of FSH and LH from the anterior pituitary gland

11. Too Much Testosterone • Stronger sex drive • may lead to risky behaviours • More impulsive and more aggressive • Mood changes • irritability and depression

12. Stimuli from other areas in the brain Hypothalamus GnRH from the hypothalamus reg- ulates FSH and LH release from the anterior pituitary. Anterior pituitary Negative feedback FSH acts on the Sertoli cells of the seminiferous tubules, promoting spermatogenesis. LH stimulates the Leydig cells to make testosterone, which in turn stimulates sperm production. Leydig cells make testosterone Primary and secondary sex characteristics Sertoli cells Spermatogenesis Testis Figure 46.14 If testosterone levels get too high

13. Female Reproductive System • estrogen • progesterone

14. Female Reproductive System • both produced in the ovaries

15. Oviduct Ovaries Follicles Endometrium Uterine wall Uterus Cervix Corpus luteum Vagina

16. Female Reproductive System • comparatively more complicated than male reproductive system • Each ovary contains about 400,000 follicles at puberty • Only about 400 eggs will mature and go through ovulation throughout a woman’s life • Monthly cycle until menopause (~12 x 50 yrs) = 400-450 cycles • female hormones responsible for oogenesis (development of mature egg cells) and ovulation

17. Ovary Follicle Cells • primary oocyte fertilized by sperm • granulosa cells provide nutrients for primary oocyte

18. Female Reproductive System

19. Female Gonad Development • GnRH, FSH and LH involved • Hypothalamus secretes gonadotropin-releasing hormone (GnRH) • Anterior pituitary gland releases FSH & LH • FSH matures follicle • LH causes ovulation and causes corpus luteum maturation

20. Menstrual/Ovarian Cycle

21. Menstrual Cycle • menstruation (flow phase) • Shedding of the endometrium • Occurs only if there is no ovum fertilization • estrogen and progesterone levels low • follicular phase • Development of follicles • estrogen secretion by granulosa cells • Estrogen signals the endometrium to thicken

22. Menstrual Cycle 3. ovulation • ovum leaves ovary • granulosa cells become corpus luteum • corpus luteum begins to secrete progesterone • estrogen levels start to decrease

23. Ovary Uterus Endometrium (a) From ovulation to implantation Endometrium Inner cell mass Cavity Trophoblast Blastocyst Figure 46.15a, b (b) Implantation of blastocyst

24. Menstrual Cycle 4. luteal stage • corpus luteum secretes progesterone & small amount of estrogen • progesterone encourages endometrium development for embryo • If no fertilization occurs = no embryo • corpus luteum degenerates after about 10 days and produces a scar (corpus albicans) • Concentrations of estrogen and progesterone decrease • Causing weak uterine contractions (marking the beginning of the flow phase)

26. http://www.youtube.com/watch?v=WGJsrGmWeKE&feature=related

27. Can a female get pregnant before she has had her first period? • YES! • By the time she has reached puberty  400,000 follicles (no Corpus Luteum) • Hypothalamus GnRH • AP  FSH, LH • FSH  induces development of follicles • Ovulation occurs before menstruation!

28. What regulates the events of the menstrual/ovarian cycle? • Varying levels of LH and FSH • determined by varying levels of estrogen and progesterone • Many different positive and negative feedback mechanisms involved

29. 2 • Follicular Phase • Low level of estrogen inhibits production of LH and FSH (keeping their levels low) • Inhibits AP to prevent ovulation • Ovulation • High estrogen stimulates LH and FSH production (more effect on LH than FSH) • Stimulates AP to cause ovulation • Luteal Phase • High levels of progesterone and estrogen inhibits LH and FSH production • Inhibit AP and Hypothalamus 3 1 2 3 1

30. Menopause • ovaries lose responsiveness to FSH and LH • usually occurs between ages 46 and 54 • most other mammals do not undergo menopause • thought to allow human females to take care of grandchildren rather than continue to reproduce

31. Man-opause? • Andropause  male menopause • Decreased levels of testosterone • Sex drive decreased • Increase in memory loss • Breast enlargement • Body composition = more fat, less muscle • More fat = more testosterone is converted to estrogen

32. In class work • Lab Exercise 8.5.1 (Hormone Levels During the Menstrual Cycle) Homework • Section 8.5 – Page 399 #1—5,7-13