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  3. 3. P O I N T O F V I E W Definition of fever Mechanisms of fever Development of fever Pro and contra of fever
  4. 4. DEFINITION: Fever is a rise in our body's normal temperature, which on average, is 98.6 degrees Farenheit. Fever is part of our body's defense mechanism. FEVER <ul><ul><li>Fever is a symptom of an infection. </li></ul></ul><ul><ul><li>Fever is a good thing. </li></ul></ul><ul><ul><li>Fever is our body's natural response to fighting germs. </li></ul></ul><ul><ul><li>The cause of the fever is quite an intricate process. </li></ul></ul>
  5. 5. CAUSES OF FEVER <ul><li>When infection occur, our blood and lymphatic system produce </li></ul><ul><li>white blood cell which are what fight off infection. </li></ul><ul><li>As the white blood cells increase in number to fight and attack the </li></ul><ul><li>germs, this causes our body to heat up. </li></ul><ul><li>The white blood cells that are produced to fight the germs, </li></ul><ul><li>has affected the hypothalamus in the brain which is the body’s </li></ul><ul><li>heat regulating mechanism. </li></ul>
  6. 6. <ul><li>When the body is fighting an injury or infection, the </li></ul><ul><li>hypothalamus sets the body temperature at higher level. </li></ul><ul><li>The body compensates for this by moving blood away from the </li></ul><ul><li>skin so the amount of heat lost through the skin is reduced. </li></ul><ul><li>Therefore, the muscles might repeatedly contract to keep the </li></ul><ul><li>body warm, which causes shivering. </li></ul>
  7. 7. Mechanisms of fever Pyrogens Endogenous Exogenous
  8. 8. Endogenous <ul><li>The cytokines like ( interleukin 1) are a part of </li></ul><ul><li>the innate immune system, produced by </li></ul><ul><li>phagocytic cells, and cause the increase in the </li></ul><ul><li>thermoregulatory set-point in the </li></ul><ul><li>hypothalamus. Other examples is (IL-6) and </li></ul><ul><li>tumor necrosis factor-alpha. </li></ul>
  9. 9. <ul><li>These cytokine factors are released into general circulation where they migrate to the circumventricular organs of the brain, where the blood-brain barrier is reduced. The cytokine factors bind with endothelial receptors on vessel walls, or interact with local microglial cells. When these cytokine factors bind, they activate the arachidonic acid pathway. </li></ul>
  10. 10. Exogenous <ul><li>One model for the mechanism of fever caused </li></ul><ul><li>by exogenous pyrogens includes LPS, which is </li></ul><ul><li>a cell wall component of gram-negative </li></ul><ul><li>bacteria. An immunological protein called </li></ul><ul><li>lipopolysaccharide-binding protein (LBP) binds </li></ul><ul><li>to LPS. The LBP–LPS complex then binds to </li></ul><ul><li>the CD14 receptor of a nearby macrophage. </li></ul>
  11. 11. <ul><li>This binding results in the synthesis and release of various endogenous cytokine factors, such as interleukin 1 (IL-1), interleukin 6 (IL-6), and the tumor necrosis factor-alpha. In other words, exogenous factors cause release of endogenous factors, which, in turn, activate the arachidonic acid pathway. </li></ul>
  12. 12. <ul><li>HYPOTHALAMUS RESPONSE </li></ul><ul><li>part of the brain called the hypothalamus controls body </li></ul><ul><li>temperature. </li></ul><ul><li>Fever results from an actual resetting of the </li></ul><ul><li>hypothalamus's thermostat. </li></ul><ul><li>The body raises its temperature to a higher level by </li></ul><ul><li>moving (shunting) blood from the skin surface to the </li></ul><ul><li>interior of the body, thus reducing heat loss. </li></ul><ul><li>Shivering (chills) may occur to increase heat production </li></ul><ul><li>through muscle contraction. </li></ul>
  13. 13. <ul><li>The body's efforts to conserve and produce heat continue until blood reaches the hypothalamus at the new, higher </li></ul><ul><li>temperature. </li></ul><ul><li>The new, higher temperature is then maintained. </li></ul><ul><li>Later, when the thermostat is reset to its normal level, the </li></ul><ul><li>body eliminates excess heat through sweating and </li></ul><ul><li>shunting of blood to the skin. </li></ul>
  14. 14. <ul><li>PGE2 RELEASE </li></ul><ul><li>PGE2 release comes from the arachidonic acid pathway. </li></ul><ul><li>This pathway (as it relates to fever), is mediated by the </li></ul><ul><li>enzymes phospholipase A2 (PLA2), cyclooxygenase-2 (COX- </li></ul><ul><li>2), and prostaglandin E2 synthase which will mediate the </li></ul><ul><li>synthesis and release of PGE2. </li></ul><ul><li>PGE2 is the ultimate mediator of the febrile response. The </li></ul><ul><li>set-point temperature of the body will remain elevated until </li></ul><ul><li>PGE2 is no longer present. </li></ul>
  15. 15. PRO AND CONTRA FEVER <ul><li>causing an unbearable environment for some pathogens </li></ul><ul><li>white blood cells rapidly proliferate due to the </li></ul><ul><li>suitable environment </li></ul><ul><li>help fight off the harmful pathogens and </li></ul><ul><li>microbes that invaded the body </li></ul>
  16. 16. <ul><li>Research has demonstrated that fever has several important functions in the healing process: </li></ul><ul><li>increased mobility of leukocytes </li></ul><ul><li>enhanced leukocytes phagocytosis </li></ul><ul><li>endotoxin effects decreased </li></ul><ul><li>increased proliferation of T Cells </li></ul><ul><li>enhanced activity of interferon </li></ul>
  17. 17. <ul><li>However, if a fever goes too high, measures </li></ul><ul><li>must be taken to bring the fever down a bit. </li></ul><ul><li>Antipyretics are medications that lower fever, </li></ul><ul><li>such as tylenol, aspirin and so on. </li></ul><ul><li>Never give a child aspirin products if it is </li></ul><ul><li>believed they have chicken pox or the flu. </li></ul><ul><li>Lead to a condition called Reye's Syndrome that </li></ul><ul><li>is potentially fatal. </li></ul><ul><li>Above 105 degrees, damage can occur in the </li></ul><ul><li>nervous system. </li></ul>
  18. 18. THE END Thank you for listening…