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Male Reproductive system

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  • 1. REPRODUCTION
  • 2. The Male Reproductive System
    • 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.
    • P2: Demonstrate a knowledge of the path of sperm from the seminiferous tubules to the urethral opening
  • 3.  
  • 4.
    • Testes (singular = testis)
    • Male gonads
    • Suspended outside the abdominal cavity in the scrotum
    • Hang outside the body to ensure optimal temperatures for sperm production (a few degrees below body temperature is required)
    • Testes descend into scrotum during last 2 months of fetal development
      • If testes do not descend, sperm can not develop properly
        • Male may become sterile
        • Increased chance of testicular cancer & injuries
    • **Testes are able to move in and out of abdominal cavity to maintain proper temperature for spermatogenesis
    • 2 Functions
      • Make s perm in seminiferous tubules, maturing sperm are moved to the epididymis
      • Make hormones : androgens and testosterone
  • 5.  
  • 6.
    • Seminiferous Tubules~250m in length!
    • site of spermatogenesis (meiosis)
    • also produce inhibin (negative -feedback vehicle to regulate the production of testosterone )
    • Interstitial Cells
    • Site of testosterone production
    • Epididymis
    • area where sperm mature and begin to gain motility and the ability to fertilize
    • storage area for sperm
    • tightly coiled tubules
  • 7.  
  • 8.  
  • 9.
    • Spermatogenesis
    • After puberty this is ongoing (unlike females)
    • Usually100-300 million sperm delivered per ejaculate
      • Only 15% are viable, of this only 400 survive to fertilize egg
    • Vas deferens (plural = vas deferentia) (also ductus deferens)
    • storage area for sperm
    • tube which carries the sperm to the ejaculatory duct and the urethra
    • Smooth muscle contractions propel the sperm into the vas deferens
  • 10.
    • Penis
    • spongy, erectile tissue containing distensible blood spaces
    • becomes erect during sexual arousal due to an increase in arterial blood flow to the penis caused by parasympathetic nerves
    • flaccid if not sexually aroused
  • 11. P3: List the functions of the seminal fluid
    • Semen ( seminal fluid)
    • thick, whitish fluid
    • contains sperm and fluids from the seminal vesicles, the prostate and Cowper’s gland.
    • is used for nutrition , motility , neutralization, and lubrication
    • Seminal Vesicles :
    • lie at base of bladder
    • 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
    • Prostate gland
    • Secretes a milky alkaline buffer that protects the sperm from the acidic environment of the vagina.
    • Helps activate sperm, helps with motility
  • 12.  
  • 13. y
  • 14.
    • Cowper’s gland (bulbourethral glands)
    • 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.
    • May also help to lubricate the urethra
    • Urethra
    • Double purpose tube (semen&urine) but NEVER at same time
    • Semen is expelled out of the urethra by rhythmic smooth muscle contractions = male orgasm
  • 15.
    • Sperm
    • Several hundred million released per ejaculate
    • fewer than one hundred even get close to the ovule
    • Only ONE will fertilize the egg (if any!)
  • 16. P4: Identify the tail, midpiece, head and acrosome of a mature sperm and state their functions.
    • 3 Distinct Parts
    • Head
    • contains the nucleus (23 chromosomes)
    • covered by a cap ( acrosome ) which stores enzymes needed to penetrate the egg/ovum
      • also provides chemical guidance system
  • 17.  
  • 18.
    • Middle Piece (midpiece)
    • contain microtubules similar to cilia or flagella
    • mitochondria are wrapped around the microtubules to provide energy for movement/swimming
    • Tail
    • microtubules only which “whip” back and forth to “ swim ” to the ovule.
  • 19. P6: Demonstrate a knowledge of the control of testosterone levels by the endocrine system .
    • Hormonal Regulation in Males
    • hypothalamus secretes gonadotropic releasing hormone (GnRH)
    • GnRH stimulates the anterior pituitary to secrete the gonadotropic hormones:
    • Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
    • [this is true of both males and females]
  • 20.
    • FSH
    • promotes spermatogenesis
    • Act directly on the sperm producing cells of the seminiferous tubules
    • LH
    • controls the production of testosterone
    • acts directly on the testosterone producing interstitial cells
    • 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 .
  • 21. P5: Describe the functions of testosterone.
    • Testosterone
    • main male sex hormone
    • produced in the interstitial cells in the testes
    • responsible for the normal development and functioning of the male sex organs
    • necessary for the maturation of sperm
    • Secondary Sex Characteristics
    • - body and facial hair growth
    • - deepening of voice (voice box enlarges)
    • - growth spurt
    • - broad shoulders, longer legs relative to trunk length
    • - greater muscle strength
    • - oil and sweat glands will secrete more
    • - baldness
    • also responsible (they think!) for sex drive
  • 22.  
  • 23.