13 / 68
6.1 The thermal regulation
machine in the human body
Human beings are warm-blooded, which means
that their internal body temperature must stay
close to 37°C (±0.5°C).
When conditions become uncomfortable, the human
body reacts by calling on a number of physiological
mechanisms that help to achieve a state of thermal
stability:
g
Vasoconstriction
helps to regulate blood circul-
ation by reducing the flow of heat to the limbs,
while
dilatation
does the opposite
g
Shivering
causes the body temperature to rise
and changes the conditions of the heat exchanges
between the skin and the exterior air (goose
pimples)
g
Perspiring
cools down the body by evaporation
through the surface of the skin.
Thermal
comfort
6
The temperature
Heat exchanges between the exterior environment
and our bodies take place through our skin.
If the temperature of the ambient air is higher than
32.2°C, then this means the transferring of heat is
no longer sufficient to keep the body at 37°C, in
which case the sweat glands take over and produce
perspiration on the surface of our skin.
As this sweat evaporates, our skin cools down.
11