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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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gonads
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
duct system
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
accessory organs
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
slide6

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
slide7

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
penis
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
slide9

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
spermogensis
Spermogensis

spermatogonia(46 chromosomes) →

meiosis &

differentiation →

sperm cell (23 chromosomes)

route of sperm
Route of Sperm
  • during , 200–500 million sperm ejaculated in 3–4mL of seminal
  • sphincter at of bladder before ejaculation
seminal fluid semen
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
testosterone male sex hormone
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
slide14

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
by the end of this section you should be able to
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