platyhelminthes

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Anonymous
ID:
13231
Filename:
platyhelminthes
Updated:
2010-04-06 00:49:20
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platyhelminthes
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Description:
describe the basic features off a common platyhelminth
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  1. describe the basic features off a common platyhelminth
    • unsegmented flatworms
    • Acelomate (lack a coelom or body cavity) w/ parenchyma (spongy mesenchymal cells filling spaces betweem viscera, muscles or epithelia)
    • tegument (living outer covering ; used to absorb stuff in parasites) of living cells
    • incomplete gut or none at all
    • protonephridia of flame cells
    • no respiratory or circulatory systems
    • monoecious= hermaphroditic
    • ectolecithal eggs (yolk comes from outside the the egg) in parasitic and turbellarian species
    • can't synthesize fatty acids or sterol de novo
  2. Distinguish between the two types of teguments
    • Free living
    • - block style
    • - +/- cilia
    • - duo- gland adhesive organs

    • Parasitic
    • - syncytial= a large cell-like structure filled with cytoplasm containing many nuclei. (neodermata)
    • - this type of tegument is better at changing surface proteins and easier to repair
  3. what does duo-gland adhesive system mean and who has them?
    • cells that produce adhesive secretions are paired with those that produce releasing secretions
    • found in turbellarians and some free-living stages of cestoidea and trematoda
  4. What are the three types of Neodermata Platyhelminthes and what (if any) subclass are under them?
    • 1. Trematoda
    • -Aspidobothrea- transition forms, bivalve parasites
    • -Digenea- 2 hosts, snail and vertabrates, known as "flukes"
    • 2. Monogenea
    • - ectoparasites, direct life cycle
    • 3. Cestoidea
    • - tapeworms
  5. Characteristics of Aspidobothrea
    • direct life cycle= one host
    • -parasites of bivalves
    • ventral sucker(s)
    • cotylocidium larva
    • can live outside of host
    • anatomy is digenea like
  6. Characteristics of Digenea
    • AKA "flukes"
    • indirect life cycle
    • -1st host is snail (intermediate host)
    • - 2nd host is vertebrate (definitive host)
    • has multiple larvel stages
    • several pathogenic
    • second most common parasitic worm
    • incomplete gut
    • can reproduce sexually or self fertilize
  7. What are the three types of body forms found in Digenea?
    • 1. Monostome- only oral sucker
    • 2. Distome- oral and ventral sucker; most common
    • 3. Amphistome- ventral sucker at posterior margin
  8. generalized life cycle of class Digenea
  9. generalized life cycle of digenea explained
    • adult fluke
    • - hermaphrodite; in definitive host
    • eggs
    • - opurculate;ectolecthial; in feces
    • miracidium
    • - ciliated; free living, infects snails
    • sporocyst
    • - no mouth, germ balls, in snail
    • redia
    • - mouth, germ balls, in snail
    • cercaria
    • - fluke w/ a tail, free living
    • metacercaria
    • - encysted form, may be in third host
  10. Characterstics of class Monogenoidea
    • trematode like morphology
    • ectoparasite
    • posterior attachment (opisthaptor) w/ suckers and hooks
    • direct life cycle oncomiracidium larva
    • Polyembryony- maintain multiple generations on the uterus, allows for the host to be infected by multiple generations
    • not much pathology unless you have lots of them
  11. characteristics of class Cestoidea
    • tapeworms
    • pseudo-segmented aceolomates
    • no respiratory, circulatory, or digestive systems
    • indirect life cycle- predator/prey cycle
    • - adults in gut, low pathology
    • - metacestodes, pathogenic
    • hexacanth embryos- 6 hooked embryo
  12. characteristics of Cestoidea adults
    • scolex ("head" or holdfast organ) for attachment
    • - +/- hooks and suckers
    • neck is generative region
    • strobila- body region of proglottids
    • - each is functional hermaphrodite
    • - mature proglottid- reproductively mature
    • - gravid proglottid- means that it is holding eggs
    • some monozotic- unsegmented

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