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Reproductive Strategies + Male Reproductive System

Reproductive Strategies + Male Reproductive System. Reproductive Strategies . In order for fertilization and development to occur, the gametes and developing organism require a high moisture environment There are two main reproductive strategies determined by this necessity:

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Reproductive Strategies + Male Reproductive System

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  1. Reproductive Strategies+ Male Reproductive System

  2. Reproductive Strategies • In order for fertilization and development to occur, the gametes and developing organism require a high moisture environment • There are two main reproductive strategies determined by this necessity: • External Fertilization • Internal Fertilization

  3. Not only is fertilization case by case, but so is development. • Examples: Vertebrate Fertilization Development Fish External External Amphibians External External Reptiles Internal External Birds Internal External  Mammals Internal Internal

  4. External Fertilization • occurs outside the female’s body. • many eggs are necessary. • because of the low rate of fertilization success. • The eggs and sperm are both released into the environment, where fertilization occurs • The eggs are exposed to the environment and also predators. • occurs mainly in aquatic animals like fish and amphibians.

  5. Internal Fertilization • occurs inside the female’s body. • many fewer eggs are needed.  • much higher rate of fertilization success. • requires a special delivery organ to deposit the sperm (penis) • used mainly by land animals (terrestrial) like reptiles, birds, and mammals in environments where moisture is low

  6. Human Reproductive Systems

  7. The Reproductive System • The main function of the reproductive system is to produce sex cells (sperm and egg). • 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

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

  9. Male Reproductive System

  10. Testes • Production of sperm cells in males • divided it into lobules • Each lobule contains one to four seminiferous tubules • Tightly coiled structures • Function as sperm-forming factories- site of spermatogenesis • Empty sperm into the rete testis • Sperm travels through the rete testis to the epididymis • Tubes that store the sperm • Epididymis stores and matures sperm for up to 20 days • Interstitial cells in the testes produce androgens such as testosterone

  11. Major Components • Vas Deferens- Carries sperm from the epididymis to the ejaculatory duct. • Vasectomy– cutting of the ductus deferens at the level of the testes to prevent transportation of sperm. • Urethra- extends from the base of the urinary bladder to the tip of the penis • Carries both urine and sperm • Sperm enters from the Vas Deferens

  12. Male Reproductive System

  13. 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 multiplication • Elements of semen enhance sperm motility

  14. Seminal Vesicles • Seminal Vesicles- glands 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

  15. Male Reproductive System

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

  17. 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

  18. Male Reproductive System

  19. External Genitalia • Scrotum • Divided sac of skin outside the abdomen • Maintains testes at 3°C lower than normal body temperature to protect sperm viability • Penis • Delivers sperm into the female reproductive tract

  20. Anatomy of a Mature Sperm Cell Figure 16.5b The only human flagellated cell DNA is found in the head The acrosomeregion helps to dissolve the outer layer of the egg, so the sperm can enter.

  21. Hormones in Males • Testosterone: • The most important hormone of the testes • Produced in interstitial cells • Functions of testosterone • Stimulates reproductive organ development • Underlies sex drive • Causes secondary sex characteristics • Deepening of voice • Increased hair growth • Enlargement of skeletal muscles • Thickening of bones • Follicle Stimulating Hormone (FSH), Luteinizing Hormone: • Stimulate the production of testosterone and sperm cells

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