Human reproduction

• Subsections of this topic

  • Human life cycle
  • Structure male reproductive system
  • Structure female reproductive system
  • Puberty
  • Gametogenesis
  • Menstrual cycle
  • Fertilisation
  • Implantation, gestation
• Copyright Hoërskool Birchleigh - Mrs A Laas
• Meiosis


  Cell division that reduces the chromosome number by half, producing haploid gametes
• Mitosis


  Cell division that produces two genetically identical daughter cells
• Fertilisation


  The fusion of a male and female gamete to form a zygote
• Human life cycle


  1. Haploid (n) sperm

  2. Haploid (n) ovum

  3. Diploid (2n) zygote

  4. Diploid (2n) multicellular male

  5. Diploid (2n) multicellular female

  
• Male reproductive organs


  • seminal vesicle
  • prostate gland
  • Cowper's gland
  • vas deferens
  • penis
  • epididymis
  • testis
  • scrotum
  • glans
  • urethra

  
• Scrotum


  Bag of skin outside the body, 2°C lower than body temperature for best spermatogenesis
• Testis


  Oval shaped gland inside the scrotum that produces testosterone and spermatozoa

  
• Epididymis


  Stores spermatozoa to mature temporarily

  
• Vas deferens


  Tube that carries spermatozoa to the urethra
• Seminal vesicles


  Gland that secretes a sugary yellow substance for energy
• Prostate


  Gland that balances the pH of semen
• Cowper's gland


  Gland that lubricates the head of the penis to maximise sperm motility
• Urethra


  Tube for urinating and ejaculation (not at the same time)
• Penis


  Male reproductive organ for transferring spermatozoa from male to female through copulation
• Female reproductive organs


  • Fallopian tube
  • uterus
  • ovary
  • Uterus wall
  • endometrium
  • cervix
  • vagina
  • vulva
  • Opening of vagina

  
• Ovaries


  Primary sex organs that produce oestrogen, progesterone and ova
• Fallopian tube


  Extends from ovary to uterus, transports ovum and developing zygote, site of fertilisation
• Uterus


  Hollow, pear-shaped organ that cares for the embryo/foetus from implantation to birth
• Cervix


  Muscular canal at the base of the uterus
• Vagina


  Muscular tube for copulation and birth canal
• Vulva


  Opening of the vagina, including the labia and hymen
• Male puberty


  • Increased muscle mass
  • Deeper voice
  • Enlargement of penis and testes
  • Production of sperm
  • Increased sweat
  • Facial and body hair growth
  • Behavioural changes
• Female puberty


  • Increased fat deposits
  • Widening of hips
  • Breast development
  • Increased height
  • Development of ova
  • Start of menstruation
  • Growth of body hair
  • Oily skin
  • Behavioural changes
• Spermatogenesis


  1. Mitosis

  2. Meiosis I

  3. Meiosis II

  4. Growth of spermatogonia into spermatozoa

  
• Structure of spermatozoa


  • Mitochondrion for locomotion energy
  • Acrosome with enzymes to penetrate ovum
  • Tail for swimming
  • Haploid nucleus in head

  
• Oogenesis


  1. Mitosis

  2. Meiosis I

  3. Meiosis II

  4. Formation of ovum and polar bodies
• Structure of ovum


  • Jelly-like layer for protection
  • Haploid nucleus
  • Cytoplasm with yolk for nutrients

  
• Ovarian cycle


  1. Mitosis to form follicle

  2. Meiosis to form ovum

  3. Graafian follicle matures and bursts to release ovum

  4. Corpus luteum forms and secretes hormones
• Uterine (menstrual) cycle


  1. Endometrium becomes richly supplied with blood

  2. No fertilization = corpus luteum disintegrates, progesterone decreases

  3. Endometrium breaks down and is discharged as menstruation
• Menstrual cycle is approximately 28 days
• Menstrual cycle


  1. Supplied with blood

  2. Preparation for implantation of fertilized ovum

  3. No fertilization = unfertelised ovum reaches uterus

  4. Corpus luteum disintegrates = progesterone levels decrease

  5. Endometrium breaks down with discharge of blood and mucus via vagina

  6. Known as menstruation – continues for about 5 days
• Oogenesis


  The production of female gametes through meiosis
• Vas deferens


  The male reproductive tube that connects the testis with the urethra
• Implantation


  The attachment of the fertilized ovum or blastocyst to the wall of the uterus at the start of pregnancy
• Blastocyst


  A hollow ball of cells formed from the zygote (Also called a blastula)
• Testosterone


  A hormone that stimulates the maturation of sperm and stimulates puberty in males
• Oestrogen


  The hormone that causes the thickening of the endometrium and is produced by the Graafian follicle
• Fertilization


  When the nucleus of the sperm cell fuses with the nucleus of the ovum