36.8 C (97.8 F)

can creep up 1 degree F in afternoon

• rectal 0.4 degrees higher than oral
• rectal 0.2 degrees higher than core

preoptic area in anterior hypothalamus

• smoking- higher
• mastication- higher
• increase resp. rate (tachypenia)- lower

1. inputes from peripheral warm and cold receptors to the anterior hypothalmus
2. when increase firing, signal set to posterior hypothalamus (regulator/set point)
3. midbrain sends signals that can cause
   1. shivering
   2. via symp. chain, affect vasomotor tone (vasodilation) and sweating

• each alters temperature, but set point stays the same

IN FEVER, the SET POINT CHANGES.

• state of altered core temperature often associated with defensive responses of multicellular organism to invasion by matter recognized by host as pathogenic/alien

• stimulated to be released by exogenous pyrogens
• endogenous pyrogens then stimulated to cross blood brain barrier

• synthesized not stored
• mononuclear phagocytic cells
• cross the BBB
• nanogram quantities of:
  • IL-1
  • TNF alpha
  • IFN gamma

• mononuclear phagocytes (main source)
• myelomonocytic leukemia cells
• renal cell carcinoma cells
• Langerhans cells
• keratinocytes

1. exogenous pyrogens stimulated
2. mononuclear phagocytes to release
3. IL-1 which crosses the
4. BBB to stimulate
5. the preoptic area of anterior hypothalamus to release
6. arachodonic acid which stimulates production of
7. thromboxanges and PGE2 which act by increasing
8. cAMP within the cell which stimulate
9. posterior hypothalmus (thermostate) to stimulate the
10. vasomotor center which will act via
11. sympathetic efferents to
12. vasoconstrict bv's leading to
13. FEVER

• definition- generalized, coordinated, nonspecific reaction in response to microbial invader that is:
  • thermoregulatory
  • anti infective
  • anti inflam.
  • metabolic
  • procoagulant

• fever rarely go above 41 degrees C
  • cryogenic neurons increase firing to bring down temp.
    • ex: ACTH, MSH

• pro-inflam. cytokines (IL, TNF alpha), ICAM, phagocytic cells, complement

• anti inflam cytokines (IL-4, IL-10)
• ACTH
• haptoglobin

• cortisol increases
• increase gluconeogenesis
• increase catecholamines
• increase lipolysis

• relieve discomfort
• reduce mortality
• prevent febrile seizures (no real difference seen in studies)
• reduce cognitive impairment (no data)
• improve outcome of patients with stroke or brain injury
• reduce metabolic demands in patients with severe CV disease (prevent shivering)

• external cooling can cause coronary vasospasm through cold pressor response
• reduction in heat shock proteins
• adverse effects on antiperetics

NO EFFECT IN SEPSIS

• increase Ig syn.
• T cell activation
• increase cytokine production
• increase NK cell activity
• increase phagocytic cell activity
• suppress microbial growth
• reduce viral replication

• illness of more than three weaks duration
• fever greater than 38.4 on several occasions
• diagnosis uncertain after one week of study in the hospital

• infection
• neoplasms
• CT diseases
• miscellaneous

• uncommon manifestation of common diseases are more common than uncommon diseases
• observe over time
• avoid therapeutic trials
• review prescribed and social drug intake