ch 27 Reproduction

• male and female shared reproductive tasks (4) 


  -form gametes

  -copulation (bring gametes together)

  -form zygote through combined genetic info

  -support the development of the fetus
• male and female reproductive structures are ___

  homologous
• primary sex organs (gonads)

  testes (male) and ovaries (female)
• GnRH


  released from hypothalamus; reaches anterior pituitary via hypophyseal portal system
• inhibin


  released from gonads of both male and female; exerts negative feedback on FSH
• puberty

  period of life when reproductive organs grow to adult size and become functional
• diploid

  -chromosomal number is a normal number of chromosomes in most body cells

  -consists of two sets of chromosomes (one from each parent) so is labeled as 2n

  -46 or 23 pairs
• haploid

  labeled as n; number of chromosomes in a gamete and contain only one pair of genetic info

  number is 23 in humans (when sperm and egg fuse they form diploid)
• sequence of events in meiosis

  prophase - metaphase - anaphase - telophase
• which division of meiosis does dna replication occur?

  meiosis I
• meiosis II

  events mirror meiosis I except DNA is not replicated and the products are haploid
• testes

  sperm-producing male gonads that lie within the scrotum
• pathway of sperm

  epididymis - ductus deferens - ejaculatory duct - urethra
• male accessory glands


  seminal glands, prostate, bulbourethral gland
• scrotum


  sac of skin and superficial fascia containing paired testes and is cooler than core body temperature
• Reproductive system


  • Does not function continuously like other organ systems
  • Does not become active until puberty
• Four tasks of male and female reproductive organs


  • Form specialized cells for sexual reproduction called gametes
  • Bring gametes from male and female together through sexual intercourse (copulation)
  • Combine genetic information contained within gametes through fertilization
  • Support development of fetus (gestation) and birth of baby (parturition)
• Homologous structures


  Male and female reproductive structures share a common origin during development
• Primary sex organs (gonads)


  • Testes (male)
  • Ovaries (female)
• Gametes


  Sperm (male) and ova (female)
• Meiosis


  Cell division that produces gametes
• Sex hormones


  Testosterone (males) and estrogens and progesterone (females)
• Accessory reproductive organs


  Ducts, glands, and external genitalia
• Hypothalamic-Pituitary-Gonadal (HPG) Axis


  1. GnRH released from hypothalamus

  2. FSH and LH (gonadotropins) released from anterior pituitary

  3. Sex hormones (testosterone, estrogen, progesterone) act at target tissues

  4. Inhibin released from gonads exerts negative feedback on FSH
• Puberty


  Period of life when reproductive organs grow to adult size and become functional
• Meiosis


  • Unique kind of nuclear division that occurs only in gonads
  • Reduces number of chromosomes in gametes by half
• Diploid


  Normal number of chromosomes in most body cells (2n)
• Haploid


  Number of chromosomes in a gamete (n)
• Sequence of events in meiosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase
• Meiosis introduces genetic diversity, as all daughter cells are genetically different from original cell
• Meiosis reduces the number of chromosomes by half (2n to n)
• Testes


  Sperm-producing male gonads that lie within the scrotum
• Sperm delivery system


  1. Epididymis

  2. Ductus deferens

  3. Ejaculatory duct

  4. Urethra
• Accessory sex glands


  Seminal glands, prostate, and bulbo-urethral glands
• Scrotum


  • Sac of skin and superficial fascia that contains the testes
  • 3°C lower than core body temperature to support sperm production
• Testes


  • Surrounded by two tunics: tunica vaginalis and tunica albuginea
  • Divided into ~250 lobules, each containing 1-4 seminiferous tubules
• Sperm transport from seminiferous tubules


  1. Straight tubule

  2. Rete testis

  3. Efferent ductules

  4. Epididymis
• Epididymis


  Where sperm mature and are stored until ejaculation
• Ductus deferens


  Carries sperm from epididymis to ejaculatory duct
• Urethra


  Conveys both urine and semen