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Published byMartina Byrd Modified over 8 years ago
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Fever Fever describes an elevation in body temperature that results from a cytokine-induced increase in the set point of the thermostatic center in the hypothalamus.
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Mechanism Pyrogenic activator microorganisms, their products and parasites (exogenous pyrogen) viruses, bacteria, mycobacteria, fungi, and parasites non-microbial factors antigen-antibody compound, alkaloids
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Endogenous pyrogen (EP) Fever activators induce host cells to produce fever-producing substances called endogenous pyrogens. Cytokines: IL-1, IL-6, TNF- α, IFN Monocytes, endothelial cells, lymphocytes, fibroblasts
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Routes of peripheral pyrogenic signals into thermostatic center Humoral mechanisms through OVLT circulatory EP local EP activated monocytes pyrogenic activators Neural mechanism peripheral nerve and vagal nerve
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Increased set point of thermostatic center PGE2 CRH Na + /Ca 2+ cAMP Negative regulatory mediators AVP(ADH), α-MSH, lipocortin-1
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Stages The fervescence period shivering, oxidation of brown adipose tissue vasoconstriction The persistent febrile period metabolic rate↑ vasodilation The defervescence period vasodilation, sweating
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Alterations of metabolism and function Metabolism metabolic rate will increase 13% while 1 ℃ elevation in body T gulcose, adipose, protein Central nervous system headache, irritability, delirium, hallucination, febrile convulsion (children)
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Cardiovascular system (SN ↑, blood T ↑) every 1 ℃ rise in body T will lead to a 18 bpm increase in heart beats. Respiratory system ( blood T ↑→respiratory center) hyperventilation respiratory alkalosis Digestive system be suppressed(SN↑,PG) anorexia, abdominal distension, constipation, vomiting Immune system be activated APP(complements), lymphocyte activation
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Pathophysiological basis of prevention and treatment Treatment of the primary disease Anti-pyretic medications drugs (salicylate) (>40 ℃ except children, pregnant women and patients with severe heart disease) Fluid and carbohydrates
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