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The Reproductive System Ch 16a.

The Reproductive System Ch 16a. The Reproductive System. Gonads – primary sex organs Testes in males Ovaries in females Gonads produce gametes (sex cells) and secrete hormones Sperm – male gametes Ova (eggs) – female gametes. Male Reproductive System. Testes Exocrine – sperm

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The Reproductive System Ch 16a.

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  1. The Reproductive SystemCh 16a.

  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 • Ova (eggs) – female gametes

  3. Male Reproductive System • Testes • Exocrine – sperm • Endocrine - testosterone • Duct system • For delivery of sperm to female reproductive system • Epididymis • Ductus deferens • Urethra PRESS TO PLAY Figure 16.2b MALE REPRODUCTIVE SYSTEM OVERVIEW ANIMATION

  4. Male Reproductive System • Accessory organs • Seminal vesicle • Prostate gland • Bulbourethral gland • External genitalia • Penis • Scrotum

  5. Male Reproductive System Figure 16.2a

  6. Testes • Coverings of the testes • Tunica albuginea – capsule that surrounds each testis & divides it into lobules Figure 16.1

  7. Testes • Coverings of the testes (continued) • Septa – extensions of the capsule that extend into the testis and divide it into lobules Figure 16.1

  8. Testes • Olive-sized, 1½ - 1” • Each lobule contains one to four seminiferous tubules • Tightly coiled structures • Function as sperm-forming factories • Empty sperm into the rete testis (on external surface of testes • Sperm travels through the rete testis to the epididymis

  9. Interstitial cells (around seminiferous tubules) produce androgens such as testosterone • Testosterone • Causes secondary sexual characteristics • Ie. Facial hair, deepened voice,  muscle mass, thickened bones

  10. Epididymis • Comma-shaped, tightly coiled tube • Found on the superior part of the testis and along the posterior lateral side • Functions to mature and store sperm cells (at least 20 days) • Expels sperm (when male sexually stimulated) with the contraction of muscles in the epididymis walls to the vas deferens

  11. Ductus Deferens (Vas Deferens) • Carries sperm from the epididymis to the ejaculatory duct • Passes through the inguinal canal and over the bladder • Moves sperm by peristalsis • Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue sheath

  12. Ductus Deferens (Vas Deferens) • Ends in the ejaculatory duct which unites with the urethra • Vasectomy – cutting of the ductus deferens at the level of the testes to prevent transportation of sperm

  13. 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

  14. Urethra • Regions of the urethra • Prostatic urethra –surrounded by prostate • Membranous urethra – from prostatic urethra to penis • Spongy (penile) urethra – runs the length of the penis

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

  16. Prostate Gland • Size of chestnut • Encircles the upper part of the urethra • Secretes a milky fluid • Helps to activate sperm • Enters the urethra through several small ducts

  17. Hypertrophy • Makes urination difficult • Treatment • Surgery, drugs (finasteride), microwaves, inserting balloon to compress tissues, inserting a needle that emits radiofrequency radiation • Prostrate cancer • 3rd most common male cancer

  18. Prostate exam

  19. Prostate in cadaver

  20. Bulbourethral Glands • Also called Cowper’s gland • Pea-sized gland inferior to the prostate • Produces a thick, clear mucus • Cleanses the urethra of acidic urine, since it produces an alkaline fluid • Serves as a lubricant during sexual intercourse • Secreted into the penile urethra

  21. Semen • Mixture of sperm and accessory gland secretions • Milky white, sticky • Ejaculation • 2-5ml • 50-130 million sperm/ml •  200 million sperm/ejaculation

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

  23. External Genitalia • Scrotum • Divided sac of skin outside the abdomen • Maintains testes at 3°C lower than normal body temperature to protect sperm viability

  24. External Genitalia • 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. External Genitalia • Internally there are three areas of spongy erectile tissue around the urethra • Fill with blood during sexual excitement

  26. Spermatogenesis • Production of sperm cells • Make millions of sperm/day • Begins at puberty and continues throughout life • Occurs in the seminiferous tubules

  27. Processes of Spermatogenesis • Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty • Follicle stimulating hormone (FSH) (starting at puberty) modifies spermatogonia division • One cell produced is a stem cell • Type A daughter cell • The other cell produced becomes a primary spermatocyte • Type B

  28. Processes of Spermatogenesis • Primary spermatocytes undergo meiosis • Meiosis: 2 successive divisions of nucleus • ½ genetic material (23 chromosomes) • 4 haploid spermatids are produced

  29. Sperm

  30. Processes of Spermatogenesis • Spermiogenesis • Late spermatids are produced with distinct regions • Head – contains DNA covered by the acrosome • Acrosome – at tip contains enzymes that help sperm penetrate through follicle cells to egg • Midpiece • Tail – contain lots of mitochondria

  31. Move to epididymis for maturation • Sperm cells result after maturing of spermatids • Spermatogenesis takes 64 to 72 days

  32. Processes of Spermatogenesis Figure 16.3

  33. Anatomy of a Mature Sperm Cell • The only human flagellated cell • DNA is found in the head Figure 16.5b

  34. Testosterone Production • Luteinizing hormone (LH) activates interstitial cells • LH produced by anterior pituitary • LH also called interstitial cell stimulating hormone (ICSH) • The most important hormone of the testes • Produced in interstitial cells

  35. Testosterone Production • Functions of testosterone • Stimulates reproductive organ development • Underlies sex drive • Causes secondary sex characteristics • Deepening of voice • Increased hair growth • Particularly axillary, pubic and face • Enlargement of skeletal muscles • Thickening of bones

  36. Sexual infantilism • No testosterone → no 2° sex characteristics • ↓ in size and function of reproductive organs • sterility

  37. Regulation of Male Androgens (Sex Hormones) Figure 16.6

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