Page 236 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

A. Relative contribution of organs to body weight and heat production
1
Percentage of body weight 2 10% 16%
(=100%) Percentage of
heat production
2% Brain (=100%) 18%
56%
8% Other a
At rest
34%
Thoracic and 1%
abdominal 1% 8%
organs
56%
Skin and
muscles Thermal Balance
At rest
b 90%
During
physical exercise
Plate 9.1
B. Mechanisms of heat loss
1 Radiation 2 Conduction and convection 3 Evaporation
Skin Loss of heat
Heat rays Convection by
H 2 O
evaporation
50°C
Diffusion
Heat
conduction
20°C
H 2 O

Sweat
glands
C. Heat production at different environmental temperatures (unclothed, at rest)
Room temperature
Total heat loss
63J· m · s =100% 38J· m · s =100% 43 J· m · s =100% 36°C
–2
–1
–1
–2
–2
–1
30°C
By way of: Distribution: Distribution:
13% 27% 100%
Evaporation 20°C
26% 27% 0%
Conduction
and convection
61% 46% 0%
Radiation 223
Despopoulos, Color Atlas of Physiology © 2003 Thieme
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