Humans

• The male reproductive system:

  • sperm ducts - tubes that carry sperm from the testes to the urethra
  • prostate gland - gland which secretes fluid to nourish sperm
  • penis - organ that releases sperm into the vagina
  • scrotum - sac that contains the testes, protects them and keeps them cool
  • testes - produce sperm
  • urethra - tube where sperm and urine leave the body
• Sperm cells:

  • have a tail to allow them to swim
  • a haploid nucleus containing half the number of chromosomes
  • many mitochondria to produce energy
• The female reproductive system:

  • ovaries - produce eggs
  • oviducts/fallopian tubes - tubes from which the eggs travel from the ovaries to the uterus. Fertilisation happens here
  • uterus - nourishes and protects the growing embryo and foetus until birth
  • cervix - neck of the uterus
  • vagina - sperm is deposited here
• Oestrogen is produced in the ovaries and thickens the uterine lining
• Progesterone is produced in the ovaries and maintains the thickness of the uterine lining
• Egg cells:

  • have a haploid nucleus containing half the chromosomes
  • contains cytoplasm for the growth of an early embryo
  • cell membrane only allows one sperm through at a time
• Placenta:

  • exchanges materials between mother and foetus
  • produces progesterone to prevent miscarriage
  • passes oxygen, glucose antibodies and vitamins from mother to foetus
  • carbon dioxide and urea passes from foetus to mother
  • mothers blood vessels are close to the villi for diffusion of substances
• The developing embryo is contained in amniotic fluid to protect from impact
• Make secondary sexual characteristics:

  • voice deepens
  • facial and chest hair
  • sperm production starts
  • bodies become muscular
  • shoulders broaden
  • enlarged Adams apple
• Female Secondary sexual characteristics:

  • hips widen
  • period starts
  • bugger breasts
  • body hair
• Oestrogen and testosterone are responsible for the development of secondary sexual characteristics during adolescence
• Secondary sexual characteristics are physical features which distinguish the sexes but are not directly involved with reproduction