Human Reproductive System

1. Human Reproductive System • Produces, stores, nourishes and transports functional gametes (egg and sperm).

2. 1o Reproductive Organs = Gonads Gonads make gametes (sex cells)and the Sex Hormones. Ducts, accessory organs and glands assist gametes Fertilization - union of sperm and egg = zygote. 2o Reproductive Organs = External Genitalia

3. Male Gonads • Testes produce sperm and testosterone. • Female Gonads • Ovaries produces eggs, estrogen and progesterone.

4. 22 pairs of autosomal chromosomes + • 1 pair of sex chromosomes. The Sex Chromosomes XX or XY Female Male X chromosome has about 1,100 genes on it. Y chromosome has about 80 genes on it.

6. Platypus: Researchers discovered the platypus has 10 sex chromosomes, some of them linked to mammals and some to birds.

7. Endocrine Regulation of Reproduction Gonadotropin-releasing hormone (GnRH) From Hypothalamus, stimulates FSH and LH release. FSH: ↑ follicular development, ↑estrogen (females). Required for sperm production (males). • LH (ICSH in men): • Ovulation. • Regulates estrogen and progesterone (females). • ↑ Testosterone (males)

8. Phenotypic Sex Apparent anatomical sex of individual Sexual differentiation Male Female Lack of Androgens Induced by Androgens Mostly Testosterone

10. Testosterone + Mullerian Inhibiting Factor Male

11. Quick summary: Developing embryo/fetus has undifferentiated gonads and has both Mullerian ducts (female reproductive tract) and Wolffian Ducts (male reproductive tract). IF Testosterone is elevated, and Mullerian Inhibiting Factor is present, fetus will develop male reproductive tract from Wolffian Ducts. IF the above are absent, fetus will develop female reproductive tract from Mullerian ducts.

12. 2o Sexual Characteristic Differences in anatomy and physiology between males and females = sexual dimorphism. Females Characteristic Males Pattern of hair growth Voice (pitch) Muscle mass Basal Metabolic Rate (BMR) Bone growth/density Sex drive Distribution of body fat Aggression

13. Genetic and Phenotypic Sex • If person with XY has testes that fail to • differentiate and secret hormones - Result? = genetic male, anatomical female • If person with XY has normal testosterone levels but target tissue lacks receptors - Result? = genetic male, anatomical female (testicular feminization syndrome)

15. Klinefelters’s Syndrome • Person has 47 chromosomes, the extra one is a Y, genotype = XXY = Male Reduced fertility, small testicles, enlarged breast • Turner’s Syndrome • Person has 45 chromosomes, the X or Y is missing, genotype = XO = Female Usually Infertile, short, immature sex organs at adolescence

16. Triple-X Syndrome Women with 3X chromosomes - genotype is XXX “Super-females" or “Meta-females”. Taller, long legs, slender torsos, limited fertility.  XYY Syndrome Males with extra Y chromosome - genotype is XYY.  “Super-males“ often tall, high testosterone levels.  Usually fertile.  Both often unaware of chromosomal abnormality

17. Male Reproductive Structures

18. Male Reproductive Structures 1o Reproductive organ: Testes • Held ‘outside’ body in the scrotum. • Dartos muscle wrinkles skin of scrotum. • Cremaster muscle pulls testes closer to body. • Cremaster Reflex.

19. Epididymis ~ 18 feet long ~ 3 weeks to travel through - Head - Body - Tail Stores sperm, recycles damaged ones, site of maturation of sperm Ductus deferens – starts after tail of epididymis

20. The Accessory Glands

21. Accessory Organs of the Male 1. Seminal vesicles 2. Prostate gland All secrete semen 2. Bulbourethral glands 1. Seminal Vesicles • Paired glands - secretes 60% semen volume. • Fibrinogen – converts to fibrin for clotting. • Fructose – a monosacharide for energy. • Prostaglandins – contract female tract.

22. 2. Prostate Gland • Single gland - secretes 30% semen volume. • Clotting proteins – to cause initial clots. • Fibrolysin – to liquefy clots. 3. Bulbourethral Glands • Paired glands (~5% semen volume). • Alkaline mucus secretion (to neutralize). • Lubricating properties.

23. Semen • Typical ejaculation releases 2-5 ml. • Sperm count typically 50 – 100 million per ml. • Sperm count below 20 million per ml, considered “infertile”. • Sperm must be 2-3o F cooler than rest of body, hence kept ‘outside’ in scrotum.

25. The Penis • Erectile tissue (3 masses) • Two corpora cavernosa • One corpus spongiosum(surrounds urethra) • Erection – dilation of arterial smooth muscles. Erectile Dysfunction (ED)?

26. The Female Reproductive System • Ovaries • Uterine tubes • Uterus • Vaginal canal and vagina • External genitalia

27. Female Reproductive System

29. Uterine Wall (Layers) • Endometrium - innermost layer • Functional layer, top 1/3 (sheds). • Basal Layer, bottom 2/3 (remains). • Myometrium – muscular (thickest ~90%). • Perimetrium – outermost covering.

31. The Vagina – passage, connecting uterus to external genitalia. The External Genitalia: • Labia majora – outer (larger) • Labia minora – inner (smaller) • Clitoris – erectile tissue (spongiosum) • (prepuce = hood, foreskin of clitoris) Lesser and greater vestibular glands. Mons pubis