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parasitic microorganisms
- protozoans
- helminths
- arthropods
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what are parasites
- organisms that benefit from host and cause disease
- Most medical parasites are eukaryotes that are either unicellular non-fungal (ie. protozoans), multicellular, often microscopic organisms (ie. helminths)
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parasitology
includes the study of protozoans, helminths and arthropods.
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characteristics of protozoans
- considered the 1st animals
- mostly multi-cellular, eukaryotic organisms
- have a true nucleus and membranes enclosed organelles (more sofisticated)
- reproduce asexually(binary fission or multiple fission)
- sexual reproduction (fusion of gametes)
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protozoan life cycle
- Active-trophozoites(metabolize, grow and cause disease)
- Inactive-cysts(orgnisms hatches out of cyst and metabolizes)
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importance of protozoans (protists)
- link in food chain - wetland & aquatic environments
- break down waste
- biological sewage treatment
- research(asexuals will produce genetic clones and we can study them)
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protozoan (protists)transmission
Fecal(direct,fecal-oral,vector borne, vehicle)
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protozoans(protists) are categorized into what groups
- plant-like (red tide)
- fungus-like water molds)
- animal-like can cause human disease)
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medically important animal-like protists
- Mastigophorans
- Sarcodines
- Apicomplexans
- Ciliates
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mastigophorans
- have flagella (motile)
- Trichomonas
- Giardiasis
- leishmaniasis
- African Sleeping Sickness
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Sarcodines
Move by pseudpodia- Amebiasis
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Apicomplexans
- are immobile so use toxins to sread
- Taxoplasmosis
- Cryptosporidiosis
- Malaria
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Ciliate
have cilia over most of their surface which allows them to move food and themselves
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Helminths
- Multi-cellular with bilateral symmetry
- 3 distinct layers-ectoderm, mesoderm, endoderm
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helmints reproduction
- asexual-hermaphoditic(male & femal rep. organs), all tapeworms and some flukes.
- sexual -all roundworms and some flukes
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Helminths life cycle
- 1. egg transmitted into the environment
- 2. Larvae- mature when get into host
- 3. adult worm
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Helminths tansmission
- fecal-oral
- direct skin
- vector borne
- vehicle
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Roundworm (hematodes)
- long thin un-segmentes tubelike bodies
- fluid filled internal body cavity(pseudocoelum) provide rigidity
- use longitudal muscles to produce sideways thrashing movement
- no respiratory or circulatory system so use diffusion to get nutrients
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Flatworm (acoelomate)
- lack internal body cavity
- Cestodes
- Trematodes
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Cestodes (tapeworm)
- long flat ribbon-like bobies
- scolex and numerous segments that can break off and move throught the body and contain 1000's of eggs
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Trematodes
- small flat leaf-like bodies
- ventral suckers
- exhibit gliding motion
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medically important helminths
- Roundworm-live in the intestine, muscular and/or circulatory system
- -Trichinosis(pork meat)
- -Filariasis
- Flatworm-live in or on host
- -Schistomaisis(flukes)
- -Beef tapeworm
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