Parasitology Symbiotic relationship 08 20 2012 Parasite an organism that lives in on another organism for prolonged period of time Commensalism Mutualism Parasitic both benefit one benefits the other unharmed one benefits other harmed but not killed usually o parasites evade internal immune system Parasitic Groups Protozoa Helminths Arthropods Parasitic Disease Direct effect parasite itself Indirect effect the presence of parasite triggers host defense mechanisms Ex Neutrophil doesn t attach to parasite but it releases particles into host system damaging host tissues Host Parasite Relationship parasite endeavors to remain in on host host endeavors to defend against ultimately remove parasite INNATE Does not require prior exposure to anything foreign not self ACQUIRED Requires prior exposure to a specific foreign not self substance Host defense mechanisms 1 first line physical barriers to ability of parasite to invade host 2 second line innate nonspecific defenses of host always on 3 third line specific acquired prior exposure required your immune system Immunity form Gr word for exempt 1 Physical Barriers Skin and mucous membranes and their secretions SKIN unbroken dry keratinized surface skin membranes are tight unpenetrated they provide a good defense MUCOUS MEMBRANES linings of respiratory GI and urogenital tracts same function as skin but moist not keratinzed SECRETIONS sweat saliva tears mucous layer of mucous membranes even urine contain enzymes that have antimicrobial properties 2 Second Line nonspecific same type of response against any foreign substance blood is considered a tissue leukocytes WBC A Phagocytosis involves phagocytic white blood cells Your Professional Phagocytes 1 Neutrophils a granulocyte comprise the largest numbers in your white blood cell count WBC s circulating in blood first WBC to arrive at site of injury or infection in your body contain efficient killing mechanisms granules in the cytoplasm containing hydrolytic enzymes for killing and lysosomes for degrading phagocytosed organisms find locations of injury or infection by chemotaxis short lived do not divide outside of bone marrow Seek Destroy and Die is their creed 2 Monocytes in blood Macrophages circulating outside of blood Big Eaters When in blood called monocytes When leave to go to tissues called macrophages Arrive after neutrophils at sites of injury infection Long lived will divide on site in tissues Efficient killers as well as scavengers cleaning up damaged and dead cellular debris Can migrate to where are needed in body o have kidney bean shape B Roles of other white blood cells in defense 1 Eosinophils has bi lobe nucleus big stain bright red also a granulocyte filled with granules containing enzymes and other proteins that aid in killing very limited phagocytic ability Found in high numbers in circulation in two conditions o a Parasitic infections b Allergic reactions 2 Basophils another granulocyte low concentrations less than 1 in circulation these granules are filled with substances that help mediate inflammatory response in body o Mast Cell a cell found in tissues not circulation a tissue counterpart of basophils in function contain granules that are mediators of inflammation 3 Natural Killer Cells aka NK cells a cytotoxic cell non specific capable of lysing cells o kills infected cells tumor cell by attaching to membrane of said cell releasing proteins that destroy the infected cell or tumor cell membrane arises from the lymphoid cell lines in bone marrow can protect you without the help of immune system o in a purple top tube there is an anti coagulant present to prevent clotting to separate the plasma from serum o in a red top tube no anti coagulant so that the particulates get tied up in the clot C Nonspecific Circulating Proteins Anti microbial 1 Complement Cascade a series of plasma proteins circulating in the blood can be activated by infection injury activation involves a cascading series of reactions A activates B which activates C etc final complex kills cells by destroying cell membrane attach to the cell membrane cause cell to lyse 2 Cytokines messengers protein hormones released by white blood cells that are chemical o affect cell producing them or o affect nearby cells o affect cells located far from producing cell or Table 3 2 in text lists some important cytokines in your body long list o IL1 IL2 IL interleukin play very important roles in your specific immunity o Tumor Necrosis Factor Alpha TNF Interferons etc INFLAMMATORY RESPONSE the nonspecific response of your body to any infection or tissue injury can be elicited by any injurious agent occurs only in living organisms no such thing as post mortem inflammation exhibits Four Cardinal Signs Redness Swelling Heat and Pain Redness and heat result from increased blood supply to affected area from dilation of vessels Swelling results from the fluid leaking from the blood and WBC s leaving blood to go to affected area Pain results from damage to and effects of swelling on peripheral nerve ending in affected area Release of mediators of inflammation chemical messengers released by injured cells infectious agents Mast cells in injured tissues will degranulate releasing histamine heparin bradykinins etc Injured cells release prostaglandins These mediators cause the inflammatory response to occur You get the picture the affected area of your body sends out an alarm call for your body s defenses to swing into action That first step is the inflammatory response Calor rubor tumor dolor heat redness swelling pain Lesion any pathological change in tissue not specific term Pathology abnormal conditions created as a result of the structural and functional changes caused by the disease processes Purulent exudate pus o dead neutrophils dead tissue extravascular fluid Abscess pus filled cavity lesion created by inflammatory process Ulcer lesion that opens to surface Acute Inflammation Site of tissue injury damage infection Sudden onset first responders still main cell population at site Chronic Inflammation Ongoing inflammation o Stimulating continues o Causative agent still present Macs are now the major inflammatory cell population Granuloma an accumulation of inflammatory cells especially macs around inflammatory causative agent This accumulation becomes walled off by fibrous connective tissue isolating the causative agent 3 Third Life of Defense Immune Response Specific Response is to a particular substance Improves with each
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