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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. 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.

  4. 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

  5. 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

  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 • divided it into lobules • Each lobule contains one to four seminiferous tubules • Tightly coiled structures • Function as sperm-forming factories • Empty sperm into the rete testis • Sperm travels through the rete testis to the epididymis(stores the sperm) • Epididymis stores and matures sperm for up to 20 days • Interstitial cells 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. Seminal Vesicles • Seminal Vesicles- 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

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

  14. 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

  15. 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

  16. 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

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

  18. 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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