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20 Cards in this Set
- Front
- Back
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Amoeboid protozoans
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Have pseudopods for movement.
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Entamoeba
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Species of Amoeboid protozoan that causes dysentery. Occurs in tropical areas with poor management of human sewage.
Symptoms: Diarrhea, blood and mucus in stools, dehydration. |
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Life cycle of Entamoeba
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1. Resistant cyst stage, passes through stomach unharmed.
2. Cyst divides into adult (trophozoite) stage, migrates to intestines, lungs, liver. 3. Lay eggs that pass out through feces. |
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Sporozoans
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Have resistant spore stage.
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Malaria cycle
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1. Sporozoite is injected into human host by mosquito. Flows in the blood stream and is filtered out by the liver.
2. Merozoite stage of malaria resides in liver, dividing and destroying liver tissue. Can burst out of RBCs, causing fever then chills. 3. Gamete stage of malaria enters another mosquito when it feeds. Cycle continues. |
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Flagellates
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Have flagella, many have trophozoite (mobile, feeding stage) and a cyst stage.
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Giardia
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Cysts released in feces of various animals. When consumed, cysts divide into trophozoites that gradually destroy the intestines.
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Trophozoite stage
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Mobile, feeding, adult stage.
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Trichomonas vaginalis
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Lacks cyst stage, very fragile. Sexually transmitted, can cause sterility in women.
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Trypanosomes
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Long, flat protists, often with flagella attached.
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T. brucei
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Causes African sleeping sickness, transmitted from bite of Tsetse fly. Chronic fatigue and lowered immunity, but not fatal in itself.
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T. cruzi
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Cases Chagas disease. Symptoms include heart and brain damage, and death. Infects several million each year in Americas:
1. Intermediate host, reduviid bug, bites infected animal and absorbs T. cruzi. 2. Trophozoite stage multiplies in bug's body, and is in its feces. 3. Reduviid bug bites host and deposits feces that contain trypanosomes. Host scratches, infecting bite with T. cruzi. 4. Cycle continues when another bug bites infected host. |
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Platyhelminthes
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Flatworms
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Flukes
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Flatworms with suckers for attachment to host's internal organs.
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Blood fluke Schistosoma mansoni
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Causes Schistosomiasis, disease that damages heart and kidneys.
Young fluke larvae develop in aquatic snails. Bore hole out of snail and emerge as a swimming cercaria stage and penetrate human skin. Usually not fatal. |
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Nematodes
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roundworms
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Pinworms
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Roundworm causes Enterobiasis.
Female pinworm leaves rectum while host sleeps, and deposits eggs on the perianus. Host scratches, eggs collect under fingernails, spread to other people. |
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Pork roundworm
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Trichnella, causes trichinosis.
Pig consumes infected fecal matter. Larvae form cysts in pig muscle. Released when humans eat raw pork. Migrate through body, using bloodstream for transport. Organs may be punctured, resulting in internal bleeding. |
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Acarines
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Some ticks inject spirochete bacteria.
In Lyme disease, a rash may form around bite in bull's-eye, later symptoms include joint inflammation and muscle paralysis. |
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Flavivirus
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Injected by mosquitoes.
Studded with E-proteins that attach to surface of monocytes, keeping defense cells from fighting other invaders. Body's defenses are overwhelmed. E.g. Dengue fever: High fever, sharp pains in joints and muscles. |
