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Defenses against Disease - Coggle Diagram
Defenses against Disease
Plant Defences
Receptor cells are stimulated by pathogen attacks and release signaling molecules to stimulate an immune response
A polysaccharide called callose is produced - acts as a barrier between plant cells and the pathogen
chemicals are also produced which kill pathogens. Some of these are extracted for use by humans - such as insect repellents
Animal Defences
Non specific defences
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mucous membranes - produce mucus which traps pathogens. Cilia then sweep it down to the stomach. Mucus also contains lysozymes which can break down pathogens
Lysozymes in tears and urine, stomach acid can kill pathogens
expulsive reflexes - coughs and sneezes which eject pathogens. vomiting and diarrhoea can expel pathogens from stomach
inflammatory response - localised response to pathogens. Results in swelling. Histamines cause blood vessels to dilate, resulting in redness and swelling, while cytokines attract phagocytes to the area
fever - inhibits pathogen reproduction. specific immune response works faster at higher temperatures
phagocytosis - from macrophages and neutrophils. Pathogens produce chemicals that attract phagocytes. Phagocyte recognizes it as non self and engulfs it, enclosing it in a vacuole - a phagosome. Combines with lysosome to form a phagolysosome. Enzymes from the lysosome engulf and destroy the pathogen. Phagocyte then presents the pathogen's antigens to attract other immune cells
Specific defences
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T memory cells - part of immunological memory. if they meet a pathogen again, they divide rapidly into T killer cells to destroy it
T killer cells - produce perforin which makes holes in pathogen cell membrane so it is freely permeable
T regulator cells - suppress the immune response once the pathogen has been eliminated. helps prevent autoimmune response
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b memory cells - live for a long time. able to produce antibodies for a previously recognised pathogen
clonal selection -when a T helper cell binds to a B cell presenting with the correct antibody. activated B cell rapidly divides to form plasma cells and memory cell. clonal expansion
Antibodies - agglutinins - stick them together so they are easier to engulf. opsonin - identifies the pathogen so it can be easily recognised and responded to. Antitoxin - neutralise the toxins produced by bacteria