Exam 2 Flashcards
Define symbiosis
permanent association of two organisms that can’t exist independently
Define mutualism
both organisms benefit
Define commensalism
one organism benefits and the other is unharmed
Define facultative parasite
live both a free living and parasitic existence during their life cycles
Define obligate parasites
completely dependent upon the host for existence
What type of parasite causes an infestation?
ectoparasite
What type of parasite causes an infection?
endoparasites
What is a definitive host?
host in which the adult or sexual stage of the life cycle occurs
What is an intermediate host?
host in which the asexual or larval stage of the life cycle occurs
What is a reservoir host?
animals other than man which harbor human parasites
What are the requirements for transmission of a parasite infection?
source of infection, mode of transmission and the presence of a susceptible host
What are the characteristics of a susceptible host?
resistance and habits are conducive to his becoming infected
Function of ectoplasm
excretion, movement, obtaining food/phagocytize, protection
Function of endoplasm
reproduction (mitosis) and digestion
Classes of protozoa
sarcodina, ciliate, mastigophora, sporozoa
What is sarcodina’s (amoeba) means of motility?
pseudopod
What is ciliate’s means of motility?
cilia
What is mastigophora’s means of motility?
flagella
What is sporozoa’s means of motility?
no means of motility in the adult, except the microgamete which uses flagella
What is the most important parasitic amoeba?
Entamoeba histolytica
Where does Entamoeba histolytica live?
large intestine
Exhibits progressive directional movement, contains one nucleus with a central karyosome and even-staining peripheral chromatin and may contain ingested RBC
Entamoeba histolytica trophozoite
Contains up to four nuclei and has cigar-shaped chromatoidal bars
Entamoeba histolytica cyst
What does Entamoeba gingivalis resemble?
Entamoeba histolytica
What are the exceptions to Entamoeba gingivalis resembling Entamoeba histolytica?
its habitat is the mouth, not the colon; and it has no cyst stage
Where does Entamoeba coli live?
large intestine
Exhibits sluggish, random motility; contains one nucleus with an eccentric karyosome and uneven peripheral chromatin; and contains ingested bacteria
Entamoeba coli trophozoite
Contains up to 8 nuclei and chromatoidal bars (if present) are irregular with splintered
Entamoeba coli cyst
Where does Endolimax nana live?
colon
Endolimax nana is recognized by its characteristic..
nuclear structure, large irregular eccentric karyosome “lump of coal,” seen in both the troph and cyst
Describe Endolimax nana cyst
ovoid, up to 4 nuclei and no chromatoidal bars
What other organism does Entamoeba hartmanii look exactly like?
Entamoeba histolytica, but it is smaller
How is Iodamoeba butschlii most easily recognized?
in the cyst form, presence of a large glycogen body
How will the large glycogen body of Iodamoeba butschlii stain with iodine?
golden-brown
only amoeba with two nuclei in the trophozoite stage and has no cyst stage
Dientamoeba fragilis
What are Charcot-leyden crystals?
refractile, long spicules produced by trauma to the GI tract that are indicative of the presence of intestinal parasites
What parasite particularly shows Charcot-leyden crystals?
Entamoeba histolytica
What are Charcot-leyden crystals composed of?
granules of ruptured eosinophils
What condition can Naegleria fowlerii cause?
rapidly fatal form of meningitis
Where do patients acquire Naegleria fowlerii?
swimming and/or diving in stagnant ponds
How can Naegleria fowlerii be best observed?
examining the CSF with a hemacytometer
What is the only parasitic member of the class Ciliata?
Balantidium coli