Page 131 - Engineering in Nature

Harun Yahya

Heat exchange takes place here, just as in the vein. But although the
blood in the vein is cold, that tissue is warmed by blood from the tho-
raic region.
Theoretically, one should expect a heat transfer from the warmer
blood to the cold. In such a transfer, the heat in the thorax will spread
to the abdomen by means of the circulatory system, and no matter
how much the moth shivers, it will never achieve the temperature
high enough for flight. Furthermore, the air sacs will serve no pur-
pose for heat insulation.
Yet none of these unwelcome developments actually takes place,
because all the needs essential to the moth's survival have been ar-
ranged with a marvel of biological engineering. What permits this
regulation is called a counter-current heat exchanger.
In this system, two liquids (or gasses) in two different but touch-
ing, or contiguou s, channels flow in different directions. If the liquid
in one channel is warmer than the liquid of the other, heat will pass
from the warmer one to the colder.
In the moth are two counter-current heat exchangers. The first of
these is the abdominal heat exchanger. As its name implies, it's lo-
cated in the abdomen, immediately beneath the air sacs, and there,
the cold blood in the vein and the warm blood in the tissue flow in op-
posite directions.
As the cold blood from the abdomen flows to the thorax, warm
blood flows from the thorax to the abdominal region. This flow
causes heat to pass from the tissue to the vein, and from there to the
thorax. The heat given off from the thorax is thus loaded onto the cold
blood entering it. In this way the heat in the thorax is prevented from
passing to the abdomen.

Adnan Oktar
129