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Reproductive Hormones

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Presentation on theme: "Reproductive Hormones"— Presentation transcript:

1 Reproductive Hormones

2 Male Reproductive Hormones
androsterone testosterone

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

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

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 To Much Testosterone Stronger sex drive
may lead to risky behaviours More impulsive and more aggressive Mood changes irritability and depression

12 If testosterone levels get too high
Stimuli from other areas in the brain Hypothalamus GnRH from the hypothalamus reg- ulates FSH and LH release from the anterior pituitary. 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. Anterior pituitary Negative feedback 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 Vagina Uterus Cervix Ovaries Oviduct Uterine wall Endometrium Follicles Corpus luteum

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

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)



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 Follicular Phase Ovulation Luteal Phase 2 3 1 2 3 1
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 2 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 (Hormone Levels During the Menstrual Cycle) Homework Section 8.5 – Page 399 #1—5,7-13

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