Parasites

• Parasite:

  An organism that lives in ( endoparasite ) or on( ectoparasite ) a host and causes harm.

  ( obtain nutrients from the host without killing it )
• General problems encountered by gut cells:

  • anaerobic conditions- little oxygen
  • Extreme acidic or alkali conditions
  • Digestive juices and churning of food inside gut
  • immune system of the host
  • Death of host = death of parasite
  • competition with other parasites
• Adaptations of parasites

  • Hooks and suckers
  • Thick cuticle - digestive juices unable to break it down
  • Long flattened body- Large surface area for absorption of pre-digested food from host
  • Simple structure- (reproduction only, simple excretory and nervous system ) conserves energy
  • Self - fertilisation - male and female reproductive organs
  • Vat number of eggs produced  (40 000 per mature segment)
• Structure of tapeworm

  Ribbon-like body up to ten meters long

  The body consists of linear series of thin segments ( proglottids )

  Head ( scolex ) of muscle containing suckers and hooks
• cycle of parasites 

  The adult tapeworm is attached to the human intestine 

  • It has both male and female reproductive organs(hermaphrodite)
  • The eggs are egested in human faeces
  • Pigs ingest the eggs via contaminated vegetation
  • The larvae hatch and move to the muscle tissue, where they become cysts
  • Humans eat the pork muscle and if uncooked the cysts move through the digestive system into the intestine, where one will attach and mature into an adult