1. Hypothalamus, temperature regulation

2. The balance between heat production and heat loss, determine body temperature

3. Heat production
From all vital process in the body, endocrine, muscular exercise & foods intake

4. Heat loss
Radiation, conduction & evaporation

5. Normal body temperature 36.3 - 37.1 C
Core temperature undergo regular circadian fluctuation of C

6. Temperature regulating mechanisms
Skin, deep tissues, spinal cord, extrahypothalamic region of the brain & hypothalamus (send information about body temperature through sensory receptors (cold receptors))
Hypothalamus integrate information, then produce integrated body temperature

7. Temperature regulating mechanisms
Heat conserving mechanisms:
Shivering
Hunger
Increased voluntary activity
Increase secretion of A & NA
Cautious vasoconstriction
Curling up
horripilation

8. Temperature regulating mechanisms
Heat loosing mechanisms
Coetaneous vasoconstriction
Sweating
Increased respiration
Anorexia
Apathy & inertia

9. Fever
During fever the thermoregulatory mechanism behave as if they were adjusted to maintain body temperature at higher levels
Resetting of the thermostat to new temp. above 37C
temp. receptors then signals that the actual temp. is below the new set point
Temp. raising mechanisms activated

10. Pathogenesis of fever
Indotoxins (from bacteria), inflammation
»»»»» act on monocytes, kupffer cells & macrophages to produces cytokines (act as endogenous pyrogens)
»»»»» activation of preoptic area of hypothalamus
»»»»» prostaglandin release in hypothalamus
»»»»»raise temp. set point »»»»» Fever

11. Benefit of fever Inhibit microrganisms growth
Antibody production increase when temp. elevated
Slow growth of some tumours (lymphoma)

12. High temp. is harmful
Permanent brain damage if rectal temp. above 41C
Above 43C heat stroke develop & death

13. Malignant hyperthermia (gene mutation)
Excess Ca released during muscle contraction
»»»»» contracture of muscle
»»»»» increased muscle metabolism
»»»»» increased heat production
»»»»» increased body temp. which it is fatal if not treated

14. Hypothermia
Decreased body temp. »»»»» slow metabolic rate & physiological process (low HR, RR, PB & loss of consciousness)
If temp. below 28C loss of spontaneous return to normal state but if warmed externally »»»»» individual survive

15. If care is taken in preventing the formation of ice crystals in tissues, then no damage is produced after subsequent warming
Human can tolerate body temp. of 21-24C during which it is possible to perform open-heart surgery & brain surgery