The Reproductive System

1. The Reproductive System

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

3. Functions 1. Produces, nurtures and transports gametes (ova/sperm) 2. Secrets hormones 3. Provide a means for fertilization 4. Provides an environment for maturation of a zygote (female reproductive system only)

4. Divisions of the Male Reproductive System • Testes • Duct System • Accessory Glands • External Genitalia We will discuss each of these in more detail

5. A. Testes Each teste is surrounded by a membrane. This membrane extends into each testis forming partitions that divide the testis into approximately 250 compartments, or lobules.

6. Seminiferous tubules • 1-4 found in each lobule • tightly coiled • sperm-forming factories

7. Rete testis *May or may not be considered an actual part of the duct system depending on the reference being used • Network of ducts (channels) • Take immature sperm cells from seminiferous tubules to epididymus

8. 2 Types of Cells within the testis • Interstitial cells: produce androgens (male hormones) such as testosterone • Spermatogenic: sperm-producing cells

9. B. Duct System • Epididymis • Ductus (vas) deferens • Ejaculatory Duct • Urethra

10. 1. Epididymis • Comma-shaped, tightly coiled tube (20 ft) • Found on the superior part of the testis along the posterior lateral side • Functions to mature and store sperm cells (at least 20 days) • Muscles in the epididymis walls move sperm to the vas deferens

11. 2. Ductus Deferens (Vas Deferens) • Carries sperm from the epididymis to the ejaculatory duct • Passes over the bladder • Moves sperm by peristalsis

12. Vasectomy cutting of the ductus deferens at the level of the testes to prevent transportation of sperm

13. 3. Ejaculatory Duct • Unites the ductus deferen with the urethra

14. 4. Urethra • Extends from the base of the urinary bladder to the tip of the penis • Carries both urine and sperm • Sperm enters from the ejaculatory duct

15. Figure 16.2b

16. C. Accessory Organs 1. Seminal vesicles 2. Prostate 3. Bulbourethral glands (Cowper)

17. 1. Seminal Vesicles • Located at the base of the bladder • Produces a thick, yellowish secretion (60% of semen) • Fructose (sugar) • Vitamin C • Prostaglandins (hormones) • Other substances that nourish and activate sperm

18. 2. Prostate • Encircles the upper part of the urethra • Secretes a milky fluid • Helps to activate sperm • Enters the urethra through several small ducts

19. 3. Bulbourethral Glands • Pea-sized gland inferior to the prostate • Produces a thick, clear mucus • Cleanses the urethra of acidic urine • Serves as a lubricant during sexual intercourse • Secreted into the penile urethra

20. Figure 16.2a

21. Semen • Mixture of sperm and accessory gland secretions • Advantages of accessory gland secretions • Fructose provides energy for sperm cells • Alkalinity of semen helps neutralize the acidic environment of vagina • Semen inhibits bacterial growth • Elements of semen enhance sperm motility

22. D. External Genitalia 1. Scrotum 2. Penis

23. 1. Scrotum • Divided sac of skin outside the abdomen • Maintains testes at 3°C lower than normal body temperature to protect sperm viability • Muscles move testes up toward body or lower away from body

24. 2. Penis • Delivers sperm into the female reproductive tract • Regions of the penis • Shaft • Glans penis (enlarged tip) • Prepuce (foreskin) • Folded cuff of skin around proximal end • Often removed by circumcision

25. Internally there are three areas of spongy erectile tissue around the urethra • Erections occur when this erectile tissue fills with blood during sexual excitement