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Sexual Reproduction

Sexual Reproduction. Male Reproductive System. Gonads. Testis : S eminiferous tubules : coiled ducts (~ long ), where ( male sex cell) made (several 100 million/day ) I ntestitial cells ( Leydig cells): between tubules & secrete

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Sexual Reproduction

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  1. Sexual Reproduction

  2. Male Reproductive System

  3. Gonads Testis: • Seminiferous tubules: coiled ducts (~ long), where (male sex cell) made (several 100 million/day) • Intestitialcells (Leydig cells): between tubules & secrete • Scrotum: sac that holds testis outside , which provides lower temperature ( °C) needed for sperm production

  4. Duct System Epididymis: • coiled tubes in sac (~6m long), where sperm mature over days & stored for weeks Ductusdeferens (Vas Deferens): • tube that sperm from testes to by peristalsis during ejaculation • curves around & empties into urethra

  5. Accessory Organs Seminal Vesicles: • produces thick, secretion into vas deferens that: • has pH (basic): protects sperm from low pH (acidic) in vagina • contains : provides energy for sperm • contains : causes uterine contractions, which sperm towards egg • located at of urinary bladder

  6. Prostate Gland: • produces thin, white secretion into deferens that: • has alkaline pH to: • neutralize pH in vagina • increases pH to activate sperm ( at pH 7.5) • helps sperm • located below urinary bladder & top of urethra

  7. Cowper’s gland (bulbourethral gland) • produces secretion into urethra that: • has alkaline to protect sperm from urine (acidic) in urethra • provides during sexual intercourse • pea–sized located below prostate • NOTE: sperm become motile (capable of ) after maturing in epididymis, but not active exposed to secretions from seminal vesicles & prostate gland in vas

  8. Penis • external structure that delivers sperm into • erectile tissue: sponge–like with many that fill with blood by constricting veins during • glans penis: head that contains many endings for sexual excitement • force of ejaculation provided by of smooth muscle in vas deferens, then skeletal in pelvis

  9. SPERM: • head: contains • acrosome: enzymes to help sperm penetrate egg • midpiece: contains mitochondria to provide energy for tail • tail: flagellum for movement • continuously made in seminiferous of testes through

  10. Spermogensis spermatogonia(46 chromosomes) → meiosis & differentiation → sperm cell (23 chromosomes)

  11. Route of Sperm • during , 200–500 million sperm ejaculated in 3–4mL of seminal • sphincter at of bladder before ejaculation

  12. SEMINAL FLUID (SEMEN) • fluid expelled from penis that secretions from , seminal vesicles, prostate gland, & Cowper’s gland • sperm in fluid survive only 24–48 h Functions • provides medium for of sperm • provides for sperm • activates sperm by alkaline pH • neutralizes urine in urethra • neutralizes acidic environment of vagina • provides which cause uterus to contract (sperm to egg) • provides lubrication intercourse

  13. Testosterone: male sex hormone • produced by testes in males & adrenal medulla in females (in lower conc.) Functions in males: • before puberty, development of penis & testes (sex organs) • at puberty, stimulates: • spermatogenesis • sex drive • development of male sex characteristics, • facial, , & pubic hair • products from oil & sweat glands in skin, which causes acne • enlargement of larynx, which causes voice • increased strength • aggression • baldness (if gene present) Function in females: • body (muscle & bone), sex drive, & pubic hair growth

  14. leutenizing hormone (LH): stimulates secretion of • follicle hormone (FSH): stimulates spermatogenesis • NOTE: testosterone also required for spermatogenesis • secretion from pituitary gland stimulated by secretion of gonadotropin hormone (GnRH) from hypothalamus • secretions from hypothalamus & anterior gland regulated by testosterone in blood plasma through negative • NOTE: LH, FSH, & testosterone secreted into blood plasma

  15. By the End of this Section You should be able to : • identify and give functions for each of the following: – testes (seminiferous tubules and interstitial cells) – scrotum – epididymis – ductus (vas) deferens – prostate gland – Cowper’s glands – seminal vesicles – penis – urethra • describe the path of sperm from the seminiferous tubules to the urethral opening • List the components seminal fluid (as contributed by the Cowper’s glands, prostate gland, and seminal vesicles), and describe the functions of each component • identify the tail (flagellum), midpiece, head, and acrosome of a mature sperm and state their functions • describe the functions of testosterone • describe the homeostatic regulation of testosterone levels by the hypothalamus, anterior pituitary, and testes

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