Chapter 1, 2, review.docx

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Health Studies
Caroline Barakat

HLTA01Plagues and People Chapter 1 2 3 Cumulative ReviewPlague plaga to strike a blow with woundsWhen a parasite invades a host it establishes an infection and wounds the body Parasitesorganism that grows feeds and is sheltered on or in a different organism and that does not contribute to the survival of its hosto Parasites are life dependent entities who feed at the table of the rich from the latin word parasites meaning food o Parasitismobtaining the resources they need for growth and reproduction eatingbreathing o intimate association of two different kinds of organisms wherein one benefits the parasite at the expense of the other the hosto When parasites often harm their hosts it is called a DISEASE o Single cellbacteria fungi protozoa o Multicellularroundworms flatworms mosquitoes flies ticks o Tapeworms hookworms malaria parasite human immunodeficiency virus HIV live inside the body whereas others ticks and chiggers live on the surface o Parasites are invariably smaller in mass than their host Ex A malaria parasite that lives within a red blood cell is 15000 of an inch in diameter If only 10 of your blood cells were infected the total mass of the malaria parasite would not occupy a thimble but could shortly destroy enough of your red blood cells leading to death Not all parasites end up killing their host because resistance may develop in any population of hosts and not every potential host will be infected some individuals may be immune or susceptible because of a genetic abnormality or the absence of some dietary factor such asa vitamin deficiencyParasites produce lots of offspring increasing the odds that some will reach new hosts which increases the probability of setting up an infection By doing this the parasite enables the chances for survival Ex When a malaria infected mosquito feeds it injects its saliva with a dozen of the thousands of parasites that are present in his salivary glands Malaria cell invades a liver cell and produces about 10000 offspring which intern affects the red blood cell and in two weeksa parson will be infected by 100000 parasites which could lead to millionsHookworms live attached to the lining of the small intestine and they suck blood Female hookworms can live in the intestine for 10 years or more producing 10000 eggs each dayAIDS causing virus HIV and after it invades a specific kind of white blood cell Thelper lymphocyte it replicates and a million viruses will be produced in a few short days empty vs crowded beach Any environment other than a living host is inimical to the health and welfare of the parasite Some parasites have spores eggs or cysts that enable them to move from one host to another akin to island hopping Hookworms tapeworms blood flutes and pinworms have eggs that are able to survive outside the bodyVirusultimate microparasitesmaller than bacteria neither cells not organisms can only reproduce within their host o Type of parasite composed of a fragment of genetic material wrapped in a protein o Smaller than bacteria and can be seen with a electron microscopeX10000 o In order for a virus to reproduce it must enter a living cell and use the cellular machinery to replace itself o Can be killed if the DNA and RNA is destroyedo Not cells or organismsMicroparasites reproduce within their hosts and are sometimes referred to as infectious microbes or germsA microparasite is a parasite that complete a full life cycle within one host and can be transmitted directly to conspecific hosts They often reproduce within a hosts cells and are generally too small to be seen with the naked eye Most are viruses bacteria and fungi with a smaller number being protists Examples include salmonella and HIVMacroparasitescomposed of many cells cycles through transmission stages eggs and larvae which pass into the external environmentdo not multiply within an infected individualMacroparasites are parasites that are large enough to be seen with the naked eye in contrast to microparasites They grow in the host but multiply by producing infective stages transmission stagesthat are released from the host allowing the parasite to spread to other hosts These generally include ticks mites nematodes flatworms etc and can be either external parasites ectoparasitic or internal parasites endoparasiticTransmissionmovement of a parasite from host to host direct or indirect o Vectors when transmission involves living organisms such as flies mosquitoes ticks fleas lice or snails o Mechanical bit wound of a mosquito or fly o Developmental parasites that grow and reproduce in snails mosquitoes o May occur through contamination of eating utensils drinking cups needles bedclothes towels or clothing o Legionnaires disease spread through a fine mist of water in the air conditioning system o SARS transmission was person to person via droplet secretions in the nose and mouthBacteria 15 picometeres in size are prokaryotes that can be free living or parasitic they can be in rods bacilli spheres cocci and spiralProtozoa 515 picometres in size are once celled eukaryotes that can lead an independent existence freshwater amoeba or parastitic entam loeba that causes amebic dystentryBacteria and protozoa are too big to be seen with a microscopeIncubation periodinterval of time required for development of a diseaseIncubation period In medicine the time from the moment of exposure to an infectious agent until signs and symptoms of the disease appearExposure presence of symptoms of parasite within the host In a vector it is the time between entrance of an organism into the vector and the time when that vector can transmit the infection For EgOnce ingested by a mosquito malaria parasites must undergo development within the mosquito before they are infectious to humans The time required for development in the mosquito the extrinsic incubation period ranges from 10 to 21 days depending on the parasite species and the temperature If a mosquito does not survive longer than the extrinsic incubation period then she will not be able to transmit any malaria parasite o the flu has a 24 day incubation period o SARS has a longer 310 day incubation period hospitalization is requiredLatent periodseemingly inactive period between exposure to an infection and subsequent illness or that between the instant of stimulation and the beginning of responseVirus latency or viral latency is the ability of a pathogenic virus to lie dormant latent within a cell denoted as the lysogenic part of the viral life cycle A latent infection is a phase in certain
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