BIOL123 - L7

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  • Created by: Katherine
  • Created on: 02-06-16 11:47
What is the most important parasitic disease?
Malaria
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What type of parasite is Malaria caused by?
Plasmodium
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How long have characteristic fevers of malaria been recorded?
Since 2700BC .
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What is malaria caused by?
The protooa from the genus Plasmodium approx 175 species currently recognised.
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What is a sporozoite?
It is a gametocyte of a plasmodium
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What causes malaria?
Sporozoites inoculated into skin by mosquit. They penetrate the blood vessel and center circulation. The circulate in the blood stream for up to 30 mins, but penetrae hapatocytes to initiate infection. .
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Once in the liver, what happens to the plasmodium?
It undergoes the process of Schizogony - a form of sexual reproduction, in which the nucleus divides many times before the cytoplasm divides to form 30000/40000 merozoites.
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What is the life cylce of plasmodium?
Mosquito feeds on human, infects sporozoites into blood, these travel to liver and invade cells. The sporozoites grow/divide and produce haploid forms called merozoiotes per liver cell.
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Some malaria parasite specie also produce hypnozoites in the live that remain fomant for extended periods, causing...
Relapses weeks or months later.
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Once the merozoites have formed, what happends?
They exit the liver cells and re-enter the blood stream, beginning a cycle of invasion of red blood cells - asexual replication. In the red blood cells, they develop into mature schizonts, which rupture, releasing newly formed merozoites, invade rbc.
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Some of the merozoites leave the cylce of asexual replication. Instead of replicating, the merozoites in these cells develop into sexual forms of the parasite (gametocytes). What happens to these
When a mosquito bites an infected human, it ingests these gametocytes. In the mosquito gut, the red blood cells burst, releasing the gametocytes with develop further into gametes.
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The games fuse to form diploid zygotes, which develop into actively moving...
Ookinetes that burrow through the mosquito migut wall and form oocystts on the other side.
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What does growth of the oocysts result in?
Produces thousands of haploid forms called sporozoites. When the mosquito takes its next meal,, it injects these sporozoites into the human
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What are hypnozoites?
It's when the plasmodium are dormant, they are less sensitive to antimalarial drugs and can reactivate many years after initial infection, leading to misdiagnosis.
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How is malaria transmtted?
Mosquito - tansmission is limited to areas in which Anopheles mosquitoes can survive and multiply but this is only between latitudes 60 nd 40' and bleow 2000 metres.
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What is the process of invasion of the erythtocyte by the merozoite?
Morphogenic maturation into ring form, attachment, reorientation and junction formation, rehoptry and microneme discharge or merozoite, past tight junction int oforming paristous vacuole, pinching off of the junction and shedding of surface coat.
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What is the eryhrocytic stage?
Merozoite - trophozoite - meorzoite or gametocyte
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What is a trophozoite?
A single celled nucleated mass of protoplasm - highly metabolically active. Needs to acquire nutrients from host cell. Modifies RBC to meet nutritional demands. Trophozoites ingest haemoglobin - this is broken down to given an iron pigement (haemozoi
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What is a merozoite?
It has apical structures and contains proteins involved in invasion. They must invade RBCs to continue infection - the erythrocytic stage of the parasite life cycle. They multiply by asexual reproduction
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What are the symptoms of malaria?
No symptoms in the incubation of 2 weeks (liver stage development) but then 3 stages.
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What are the 3 stages of malaria?
Cold stage (constant shaking chill) , Fever (41-42), Wet stage - profuse sweating
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What are the symptoms caused by?
When erythrocytes rupture and merozoites are released - toxins are released which induced pyrexia.
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What is a schizony?
Cleaving.
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What is the definitive host of malaria?
Plasmodium
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How many oocysts do the sporozoites produce?
Up to 1000
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What happens when the oocysts burst?
Sporozoites are released into the body cavity of the mosquito.
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How is malaria diagnoised?
Serological test: test for malaria specific antibodies - useful for patients with negative blood smears. Blood smears - thick and thin blood smears are prepared and staiend with giemsa stain to detect and identify the species.
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Other complications associated with malaria:
Liver failure and jaundice (yellowing of skin), shock, pulmoary odema (build up of fluid in the lungs), acute respiratory distress syndrome (body deprived of oxygen), Hypoglycaemia (abnormally low blood sugar), dehydration.
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What are other means of malatia transmission?
introduced malaria, local mosquitoes become infected by biting people carrying malaria (aquired in endemic areas), these transmit malaria to local residents. Airport malaria - caused by infected mosquitoes being transported by aircraft. Transfusion.
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Continued:
Mainline malaria - acquired via shared needles and syringes, congenital malaria - aquired via perinatal routes e.g. pregnancy.
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What is sequestration?
Trapping
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What are the complications resulting from severe malaria?
Anaemia (erythrocyte destruction) pigmentation of organs (ingestion of malatial pigment by phagocytes),hepatomegaly and splenomegaly (enlargement of liver and spleen) - dilaton of the sinuses and increased numbers of macrophages (especially in spleen
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COntinued:
Capillary blockages - parasited red blood cells block capillaries - local haemorrhage and anorexia. Intravascular haemolysis in kidney. Haeemoglobinaemia. Haemoglobinuria (Hb in urine due to RBC lysisi)
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Card 2

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What type of parasite is Malaria caused by?

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Plasmodium

Card 3

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How long have characteristic fevers of malaria been recorded?

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Card 4

Front

What is malaria caused by?

Back

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Card 5

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What is a sporozoite?

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