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Lab session 4

Lab session 4. Helminths Worms. Platyheminthes (flatworm) Nematodes (roundworms) 2 types platyhelminthes Trematodes (flukes) Cestodes (tapeworms) Flat body, hermaphroditic – both male and female reproductive organs Both testes and ovaries. Complex life cycle

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Lab session 4

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  1. Lab session 4 Helminths Worms

  2. Platyheminthes (flatworm) • Nematodes (roundworms) • 2 types platyhelminthes • Trematodes (flukes) • Cestodes (tapeworms) • Flat body, hermaphroditic – both male and female reproductive organs • Both testes and ovaries

  3. Complex life cycle • Intermediate host – larvae of the worm (immature worm), asexual reproduction takes place • Definitive host – adult worm (mature worm), sexual reproduction takes place. • Flukes – flat leaf like body • hermaphroditic

  4. Clonorchis sinensisChinese liver fluke

  5. Adult worm – bile ducts of humans • Eggs are released in the feces • When it reaches a body of water larva comes out • Ingested by a specific species of snail • Asexual reproduction takes place • Larvae come out of the snail • Penetrates a fish and forms a cyst in the fish • When people eat undercooked, contaminated fish larvae end up in the bile ducts • Develop into adult worms • Cycle continues

  6. Diagnosis is based on the presence of eggs in the feces. Flower vase Operculum Lid-like structure

  7. Cestodes (tapeworms) • Scolex – head • Segmented body • Segment – proglottids • Hermaphroditic • Each proglottid has testes and ovaries

  8. Taenia saginta (beef tapeworm) • Adult – human intestinal tract • Eggs are released in the feces • Ingested by cattle • Larvae come out in the intestinal tract • Cysts in the muscle • Cyst (sleeping, resting larva) • Undercooked, contaminated meat ingested by humans • Scolex comes out of the cyst • Attaches to the intestinal wall • Makes proglottids

  9. All tapeworms make identical eggs • Taenia pisiformis

  10. Nematodes (roundworms) • Dioecious • Male and female worms

  11. Entirobius vermicularis (pinworm) • Intestinal tract of humans • Female worm comes out of the anus • Releases its eggs • Eggs – clothing, bedding, airborne • Ingested by another host • Eggs reach intestinal tract • Larvae come out • Grows into an adult worm • Intense itching in the perianal area

  12. flat More curved Larva curled up

  13. Ascaris lumbricoides • Adult – intestinal tract • Eggs released in the feces • Ingested in contaminated food and water • Larvae come out in the intestinal tract • Grow into adult worms • Eat semidigested food • Blockage (obstruction) of the intestinal tract.

  14. Irregular surface

  15. NecatoramericanusHookworm • Adult – intestinal tract • Eggs – feces • Larvae come out in the soil • When people step on them, they penetrate the skin • Migrate to the intestinal tract • Attach to the intestinal wall • Feed on blood • Grow into adult worms • Anemia • Wearing shoes

  16. Trichuris trichurawhipworm • Adult – intestine • Eggs – feces • Contaminated food or water • Larvae come out in the intestinal tract • Bloody diarrhea

  17. Football shaped eye

  18. Trichinella spiralis • Transmitted in contaminated, undercooked • Encysted pork • Larvae come out of the cyst in the intestinal tract • Grow into adult worms • Female releases larvae • From cysts in the muscle • Diaphragm muscle

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