Fever
Fever
F ever normal body temperature 370. Circadian variation oral T0.5> axillary T(腋温)
Fever •Normal body temperature: 37oC, Circadian variation oral T 0. 5oC > axillary T（腋温）
fever Hyperthermia(体温过高) fever due to a disturbance of thermal regulatory control excessive heat production decreased dissipation loss of regulation
Fever •Hyperthermia (体温过高） fever due to a disturbance of thermal regulatory control excessive heat production decreased dissipation loss of regulation
fever Shifting of the Thermoregulatory set-point Maintaining an abnormally elevated Temperature Accelerating energy production T increase 0.6C= bMR increase 10%
Fever •Shifting of the Thermoregulatory set-point •Maintaining an abnormally elevated Temperature •Accelerating energy production T increase 0.6oC = BMR increase 10%
Pathophysiology body temperature is determined by two opposing processes heat production heat loss They are regulated by the central nervous system Energy in the form of heat is generated by living tissues(thermogenesis) Energy may be passively absorbed from the environment and transfer the energy to the surrounding medium
Pathophysiology •Body temperature is determined by two opposing processes heat production heat loss • They are regulated by the central nervous system • Energy in the form of heat is generated by living tissues (thermogenesis) • Energy may be passively absorbed from the environment and transfer the energy to the surrounding medium
Pathophysiology The body temperature is under control of the preoptic area of the anterior hypothalamus(下丘脑 Thermostat(恒温器) It receives input from both central receptors and peripheral receptors
Pathophysiology •The body temperature is under control of the preoptic area of the anterior hypothalamus（下丘脑） Thermostat （恒温器） •It receives input from both central receptors and peripheral receptors
Heat production and heat loss Basal metabolic rate is controlled by hypothalamus by varying the level of circulating thyroxine (E 腺素) Increased muscle sensitivity(shivering) e By varying the volume of blood flowing to skin's surface(100 fold By vaporization(exocrine sweating)
Heat production and heat loss •Basal metabolic rate is controlled by hypothalamus, by varying the level of circulating thyroxine （肾上 腺素） •Increased muscle sensitivity (shivering) •By varying the volume of blood flowing to skin’s surface (>100 fold) •By vaporization (exocrine sweating)
Set point Heat 390c Heat Production Loss ■■■ ■■ ■■ Heat Production 370c Heat Loss
Set point 370C 390C Heat Production Heat Loss Heat Production Heat Loss
Pathophysiology elevation of body temperature shivering thermogenesis and dermal vasoconstriction sympathetic outflow Cooling mechanism sweating and dermal vasodilation mixture of sympathetic and parasympathetic pathways
Pathophysiology •Elevation of body Temperature shivering thermogenesis and dermal vasoconstriction sympathetic outflow •Cooling mechanism sweating and dermal vasodilation mixture of sympathetic and parasympathetic pathways
Pathophysiology Hypothalamic thermostat Set point:37°C lowest: 4 a m; peak: 610 p.m Fever follow this pattern Factors affect body Temperature exerclse menstrual cvcle environmental temperature
Pathophysiology •Hypothalamic thermostat Set point: 37oC lowest: 4 a.m; peak: 6~10 p.m •Fever follow this pattern •Factors affect body Temperature exercise menstrual cycle environmental temperature