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77 Cards in this Set
- Front
- Back
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parasite
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an organism that lives at the expense of another organism (host)
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pathogens
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parasites that cause disease
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parasitology
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study of parasites
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ectoparasites
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live on the surface of other organisms
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endoparasites
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live within the bodies of other organisms
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obligate parasites
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must spend at least some of their life cycle in or on a host
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facultative parasites
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normally free-living, but can obtain nutrients from a host
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permanent parasites
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remain in or on a host once they've invaded it; eg tapeworms
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temporary parasites
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feed on and then leave their hosts; eg biting insects
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accidental parasites
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invade an organism other than their normal host; eg ticks
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hyperparasitism
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refers to a parasite itself having parasites; eg malaria
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vector
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agent of transmission
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biological vector
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vector in which the parasite goes through part of its life cycle
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mechanical vector
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vector in which the parasite does not go through any part of its life cycle during transit
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definitive hosts
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harbor a parasite while it reproduces sexually
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intermediate hosts
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harbor the parasite during some other developmental stages
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reservoir hosts
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infected organisms that make parasites available for transmission to other hosts
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encystment
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outer covering that protects against the environment, function in transmission and attachment to host
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parasite mechanisms for evading host defense
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(1) encystment; (2) change surface antigens; (3) cause host immune sys to make antibodies that cannot react w/parasites antigens; (4) invade host cells
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characteristics of protists
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kingdom Protista; diverse; unicellular, eukaryotic; true nuclei & membrane-enclosed organelles; diameter range 5um-5mm
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stigma
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pigmented eyespot on representative algae/plantlike protists
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test
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calcium carbonate shells
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oomyota
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water mold
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saprophytes
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Put corresponding gFlash+ Answer Choice here
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zoospores
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flagellated spores
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animal-like protists
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heterotrophic, mostly unicellular; free living or commensals
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mastigophorans
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have flagella, few are free-living, but most live in symbiotic relationships; eg Trypanosoma, Leishmania, Giardia, Trichomonas
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amebozoa
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usually amoeboid & move by means of pseupodia, a few have flagella at some stage; eg Entamoeba, Endolimax
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apicomplexans
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parasitic & immobile; include sporozoites, merozoites, trophozoites, and gametocytes; eg Plasmodium
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ciliates
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largest group of protozoans; have cilia over most of their surfaces for movement & assistance in food gathering
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cilia, specialized structures
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(1) contractile vacuole to regulate fluids; (2) Trichocysts tentacles to capture prey; (3) conjugation structure for genetic exchange
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characteristics of fungi
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diverse group of heterotrophs; many are saprophytes; some are parasites; most fungi, such as molds & shrooms, are multicellular, but yeasts are unicellular
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structural components of fungi
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thallus, mycelium, chitin
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thallus
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body of a fungus
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mycelium
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loosely organized mass of threadlike structures called hyphae; cells release enzymes that digest substratum
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cell wall composition, fungi
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most contain chitin (a few cellulose)
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chitin
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a polysaccharide also found in the exoskeletons of arthropods
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asexual reproduction in fungi
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always involves mitotic cell division; occurs by budding
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sexual reproduction in fungi
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(1) plasmogamy; (2) dikaryotic; (3) karyogamy
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plasmogamy
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haploid gametes unite and their cytoplasm mingles
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dikaryotic
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if nuclei fail to unite, a "two-nucleus" cell forms
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karyogamy
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eventually nuclei fuse in this process to produce diploid cell
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parasitic fungi, requirements of invasion
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(1) proximity to the host; (2) ability to penetrate the host; (3) ability to digest and absorb nutrients from host cells
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classification of fungi
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fungi are classified according to the nature of the sexual stage in their life cycles
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problems with classification of fungi
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(1) no sexual cycle has been observed for some fungi; (2) it is often difficult to match the sexual and asexual stages of some fungi
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dimorphism
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the ability of an organism to alter its structure when it changes habitats
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sac fungi that are human pathogens
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(1) candida albicans; (2) trichophyton; (3) aspergillus; (4) blastomyces; (5) histoplasma
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pathology caused by Candida albicans
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yeast infections
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pathology caused by Trichophyton
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athlete's foot
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pathology caused by Aspergillus
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opportunistic respiratory infections
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pathology caused by Blastomyces
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respiratory infections & possibly systemic infections
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pathology caused by Histoplasma
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respiratory infections & possibly systemic infections
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Cryptococcus neoformans
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yeast that causes opportunistic infections of the respiratory tract and meningitis; AIDS is most common risk factor
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characteristics of Helminths
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bilaterally symmetrical; have L & R halves that are mirror images; have head & tail ends; tissues differentiated into three distinct layers: ectoderm, mesoderm, endoderm
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Helminths that parasitize humans
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flatworms and roundworms
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Flatworms (Platyhelminthes)
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primitive worms which lack a coelom & have a simple digestive tract with a single opening; most are hermaphroditic
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Roundworms (nematodes)
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share many characteristcs with flatworms, but they have a pseudocoelom; they have cylindrical bodies with tapered ends and are covered with a thick, protective cuticle
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Parasitic Helminths
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(1) flukes; (2) tapeworms; (3) adult roundworms of the intestine; (4) roundworm larvae
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Clonorchis sinensis, the Chinese liver fluke
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infests the gallbladder, bile ducts, and pancreatic ducts, where it causes biliary cirrhosis and jaundice
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Tapeworms, characteristics
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consist of a scolex, or head end with suckers that attach to intestinal wall; long chain of hermaphroditic proglottids
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proglottids
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body components that contain mainly reproductive organs of both sexes
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1st stage, tapeworm life cycle
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embryos develop inside eggs and are released from proglottids
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2nd stage, tapeworm life cycle
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proglottids and eggs leave the host's body with the feces
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3rd stage, tapeworm life cycle
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another animal ingests vegetation or water contaminated with eggs and eggs hatch into larvae, which invade the intestinal wall
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4th stage, tapeworm life cycle
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a larvae can develop into a cysticerus (bladder worm), r it can form a cyst
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5th stage, tapeworm life cycle
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a cyst can enlarge and develop many tapeworm heads within it (hydatid cyst) and if an animal eats flesh containing this, each scolex can develop into a new tapeworm
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neurocysticercosis
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pork tapeworm
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adult roundworms that parasitize humans live
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most of life cycle in digestive tract
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adult roundworms enter body by
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ingestion with food or water, but some penetrate the skin (e.g. hookworm)
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life cycles of intestinal roundworms show
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considerable variation
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characteristics of arthropods, general
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constitute the largest group of living organisms; 80% of all animal species belong to phylum Arthropoda
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specific characteristics of arthropods
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(1) jointed chitinous exoskeletons; (2) segmented bodies; (3) jointed appendages; (4) have true coelom; (5) small brain & extensive network of nerves; (6) sexes are distinct & females lay many eggs
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classification of arthropods
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(1) arachnids; (2) insects; (3) crustaceans
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wood tick, Dermacentor andersoni
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characterized by four pairs of legs & two body regions (cephalothorax & abdomen)
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insects, body type
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three body regions (1) head, (2) thorax, (3) abdomen; three pairs of legs; highly specialized mouth parts
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crustaceans
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generally aquatic arthropods; typically have a pair of appendages associated with each segment
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crustacean appendages include
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(1) mouthparts; (2) claws; (3) walking legs; (4) appendages that aid in swimming or copulation
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