Male Reproductive system


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Male Reproductive system

  2. 2. The Male Reproductive System <ul><li>P1: Identify and give functions for each of the following: testes, seminiferous tubules, interstitial cells, epididymis, ductus (vas)deferens, prostate gland, Cowper’s (bulbourethral) gland, seminal vesicles, penis, urethra. </li></ul><ul><li>P2: Demonstrate a knowledge of the path of sperm from the seminiferous tubules to the urethral opening </li></ul>
  3. 4. <ul><li>Testes (singular = testis) </li></ul><ul><li>Male gonads </li></ul><ul><li>Suspended outside the abdominal cavity in the scrotum </li></ul><ul><li>Hang outside the body to ensure optimal temperatures for sperm production (a few degrees below body temperature is required) </li></ul><ul><li>Testes descend into scrotum during last 2 months of fetal development </li></ul><ul><ul><li>If testes do not descend, sperm can not develop properly </li></ul></ul><ul><ul><ul><li>Male may become sterile </li></ul></ul></ul><ul><ul><ul><li>Increased chance of testicular cancer & injuries </li></ul></ul></ul><ul><li>**Testes are able to move in and out of abdominal cavity to maintain proper temperature for spermatogenesis </li></ul><ul><li>2 Functions </li></ul><ul><ul><li>Make s perm in seminiferous tubules, maturing sperm are moved to the epididymis </li></ul></ul><ul><ul><li>Make hormones : androgens and testosterone </li></ul></ul>
  4. 6. <ul><li>Seminiferous Tubules~250m in length! </li></ul><ul><li>site of spermatogenesis (meiosis) </li></ul><ul><li>also produce inhibin (negative -feedback vehicle to regulate the production of testosterone ) </li></ul><ul><li>Interstitial Cells </li></ul><ul><li>Site of testosterone production </li></ul><ul><li>Epididymis </li></ul><ul><li>area where sperm mature and begin to gain motility and the ability to fertilize </li></ul><ul><li>storage area for sperm </li></ul><ul><li>tightly coiled tubules </li></ul>
  5. 9. <ul><li>Spermatogenesis </li></ul><ul><li>After puberty this is ongoing (unlike females) </li></ul><ul><li>Usually100-300 million sperm delivered per ejaculate </li></ul><ul><ul><li>Only 15% are viable, of this only 400 survive to fertilize egg </li></ul></ul><ul><li>Vas deferens (plural = vas deferentia) (also ductus deferens) </li></ul><ul><li>storage area for sperm </li></ul><ul><li>tube which carries the sperm to the ejaculatory duct and the urethra </li></ul><ul><li>Smooth muscle contractions propel the sperm into the vas deferens </li></ul>
  6. 10. <ul><li>Penis </li></ul><ul><li>spongy, erectile tissue containing distensible blood spaces </li></ul><ul><li>becomes erect during sexual arousal due to an increase in arterial blood flow to the penis caused by parasympathetic nerves </li></ul><ul><li>flaccid if not sexually aroused </li></ul>
  7. 11. P3: List the functions of the seminal fluid <ul><li>Semen ( seminal fluid) </li></ul><ul><li>thick, whitish fluid </li></ul><ul><li>contains sperm and fluids from the seminal vesicles, the prostate and Cowper’s gland. </li></ul><ul><li>is used for nutrition , motility , neutralization, and lubrication </li></ul><ul><li>Seminal Vesicles : </li></ul><ul><li>lie at base of bladder </li></ul><ul><li>secrete a thick, clear fluid containing fructose (energy), prostaglandins (chemical signal in female to trigger rhythmic contractions of smooth muscle in female – facilitates movement of sperm towards egg </li></ul><ul><li>Prostate gland </li></ul><ul><li>Secretes a milky alkaline buffer that protects the sperm from the acidic environment of the vagina. </li></ul><ul><li>Helps activate sperm, helps with motility </li></ul>
  8. 13. y
  9. 14. <ul><li>Cowper’s gland (bulbourethral glands) </li></ul><ul><li>secrete mucous secretes mucus rich fluids prior to ejaculation, thought to neutralize any remaining acidic urine in the urethra. Also contains some sperm before ejaculation – reason for high failure rate of withdrawl method of birth control. </li></ul><ul><li>May also help to lubricate the urethra </li></ul><ul><li>Urethra </li></ul><ul><li>Double purpose tube (semen&urine) but NEVER at same time </li></ul><ul><li>Semen is expelled out of the urethra by rhythmic smooth muscle contractions = male orgasm </li></ul>
  10. 15. <ul><li>Sperm </li></ul><ul><li>Several hundred million released per ejaculate </li></ul><ul><li>fewer than one hundred even get close to the ovule </li></ul><ul><li>Only ONE will fertilize the egg (if any!) </li></ul>
  11. 16. P4: Identify the tail, midpiece, head and acrosome of a mature sperm and state their functions. <ul><li>3 Distinct Parts </li></ul><ul><li>Head </li></ul><ul><li>contains the nucleus (23 chromosomes) </li></ul><ul><li>covered by a cap ( acrosome ) which stores enzymes needed to penetrate the egg/ovum </li></ul><ul><ul><li>also provides chemical guidance system </li></ul></ul>
  12. 18. <ul><li>Middle Piece (midpiece) </li></ul><ul><li>contain microtubules similar to cilia or flagella </li></ul><ul><li>mitochondria are wrapped around the microtubules to provide energy for movement/swimming </li></ul><ul><li>Tail </li></ul><ul><li>microtubules only which “whip” back and forth to “ swim ” to the ovule. </li></ul>
  13. 19. P6: Demonstrate a knowledge of the control of testosterone levels by the endocrine system . <ul><li>Hormonal Regulation in Males </li></ul><ul><li>hypothalamus secretes gonadotropic releasing hormone (GnRH) </li></ul><ul><li>GnRH stimulates the anterior pituitary to secrete the gonadotropic hormones: </li></ul><ul><li>Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) </li></ul><ul><li>[this is true of both males and females] </li></ul>
  14. 20. <ul><li>FSH </li></ul><ul><li>promotes spermatogenesis </li></ul><ul><li>Act directly on the sperm producing cells of the seminiferous tubules </li></ul><ul><li>LH </li></ul><ul><li>controls the production of testosterone </li></ul><ul><li>acts directly on the testosterone producing interstitial cells </li></ul><ul><li>testosterone itself is involved in the negative -feedback system exerted on the hypothalamus and the anterior pituitary gland to regulate testosterone levels in the blood . </li></ul>
  15. 21. P5: Describe the functions of testosterone. <ul><li>Testosterone </li></ul><ul><li>main male sex hormone </li></ul><ul><li>produced in the interstitial cells in the testes </li></ul><ul><li>responsible for the normal development and functioning of the male sex organs </li></ul><ul><li>necessary for the maturation of sperm </li></ul><ul><li>Secondary Sex Characteristics </li></ul><ul><li>- body and facial hair growth </li></ul><ul><li>- deepening of voice (voice box enlarges) </li></ul><ul><li>- growth spurt </li></ul><ul><li>- broad shoulders, longer legs relative to trunk length </li></ul><ul><li>- greater muscle strength </li></ul><ul><li>- oil and sweat glands will secrete more </li></ul><ul><li>- baldness </li></ul><ul><li>also responsible (they think!) for sex drive </li></ul>