Chapter 16 The Reproductive System Intro & Male

1. Chapter 16The Reproductive SystemIntro & Male Notice: This presentation contains actual pictures of human reproductive anatomy

2. The Reproductive System 1. Gonads – primary sex organs • Testes in males • Ovaries in females 2. Gonads produce gametes (sex cells) and secrete hormones • Sperm – male • Ova (eggs) – female

3. Male Reproductive System • Accessory organs - Seminal vesicle - Prostate gland - Bulbourethral gland • External genitalia - Penis - Scrotum • Testes • Duct system - Epididymis - Ductus deferens - Urethra

4. Testes • Tunica albuginea – capsule that surrounds each testis • Septa – extensions into testis; dividing it into lobules

5. Testes Each lobule contains 1-4 seminiferous tubules • Tightly coiled • Sperm-forming factories • Empty sperm into the rete testis Sperm travels through the rete testis to epididymis Interstitial cells produce androgens such as testosterone

6. Epididymis • Comma-shaped, tightly coiled tube • Superior and along posterior lateral side • Matures and stores sperm cells (at least 20 days) • Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens

7. Ductus Deferens • Carries sperm from epididymis to ejaculatory duct • Passes through inguinal canal & over bladder • Moves by peristalsis • Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue • Ends in the ejaculatory duct which unites with urethra • Vasectomy – cutting of the ductus deferens at the level of the testes to prevent transportation of sperm

8. Urethra • Extends from the base of bladder to the tip of penis • Carries both urine and sperm • Sperm enters from the ejaculatory duct Regions: Prostatic urethra –surrounded by prostate Membranous urethra – from prostatic urethra to penis Spongy (penile) urethra – runs the length of the penis

9. Seminal Vesicles • Located at the base of the bladder • Produces a thick, yellowish secretion (60% of semen) • Fructose (sugar) • Vitamin C • Prostaglandins • Substances that nourish & activate sperm

10. Prostate Gland • Encircles upper part of urethra • Secretes a milky fluid • Helps activate sperm • Enters urethra through several small ducts

11. Bulbourethral Glands • Pea-sized gland inferior to prostate • Produces a thick, clear mucus • Cleanses urethra of acidic urine • Lubricant during intercourse • Secreted into penile urethra

12. Semen • Mixture of sperm & gland secretions • Advantages of secretions • Fructose provides energy • Alkalinity neutralizes acidic vagina • Semen inhibits bacterial growth • Elements of semen enhance sperm motility

13. External Genitalia • Scrotum - Divided sac of skin outside abdomen - 3°C lower than body temp to protect sperm

14. External Genitalia • Penis- Delivers sperm into female repro tract • Shaft • Glans penis (enlarged tip) • Prepuce (foreskin) • Folded cuff of skin around proximal end • Often removed by circumcision

15. External Genitalia • 3 areas of spongy erectile tissue around the urethra

16. Spermatogenesis • Production of sperm cells • Begins at puberty and continues throughout life • Occurs in the seminiferous tubules

17. Processes of Spermatogenesis • Follicle stimulating hormone (FSH) regulates • Spermatogonia (stem cells) - rapid mitosis to produce more stem cells before puberty First division of a stem cell becomes 1 stem cell & 1 primary spermatocyte • Primary spermatocytes undergo meiosis • Haploid spermatids

18. Anatomy of a Mature Sperm Cell • Late spermatids - distinct regions • Head –DNA covered by acrosome • Midpiece • Tail • Sperm cells = mature spermatids • Spermatogenesis takes 64 to 72 days • Only human flagellated cell

19. Testosterone Production - Most important hormone of testes - Produced in interstitial cells - Functions • Organ development • Sex drive • Secondary sex characteristics • Deepening of voice • Increased hair growth • Larger skeletal muscles • Thicker bones

20. Regulation of Male Androgens (Sex Hormones)