Page 340 - Biology_F5

Regulation (Homeostasis)

features or mechanisms. This diversity of Another adaptation to the hot environment
living environment include the hot arid is the possession of long loops of Henle of
environment of the desert, the colder and the kidney. This enables animals to produce
glacial environments of the Arctic and super-concentrated urine that helps to
Antarctic poles, the salty environment of conserve water. This tendency is common
the oceans, low oxygen environment of for the desert dwellers such as kangaroo
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mountain peaks and the dark environments rats, and camels. Most small animals with
of the deep sea and oceans. Animals in the high surface area to volume ratio usually
face major difficulties in overcoming high
cold environment such as arctic fox have temperatures. Therefore, they remain in
insulating layers with a thick coat of fur or burrows during the day when it is hot and
thick layer of fat that help to reduce the rate come out at night when it is cool. This
of heat transfer, thereby retaining body heat nocturnal tendency enables small animals
and keeping the animal’s body temperature like rodents to survive in extremely hot
at constant level. Another strategy of climates. Some mammals that live in
cold weather used by some animals is a deserts have special adaptations in their
temporary decrease of metabolic rate and kidneys and sweat glands that allow them
body temperature. This helps to decrease to survive even when only very small
the temperature difference between the amounts of water are available to them.
animal body and the environment, thereby
minimising heat loss. Regulation of body temperature in
endotherms
Another adaptation for survival of Endotherms have developed a variety of
animals, such as bears in the extreme adaptive mechanisms for maintaining a
cold climate is hibernation during the constant or stable body temperature. The
cold period. When the body temperature adaptive mechanisms for balancing heat
falls to a few degrees, an animal falls into gain and heat loss may be anatomical,
a deep sleep. This tendency enables the behavioural, or physiological. The
animal to conserve energy. process of controlling body temperature
in endotherms falls under two homeostatic
In the hot and dry environment, endotherms systems, namely regulation of skin
develop cooling mechanism by means temperature and regulation of the body
of evaporation of water across their core temperature, which includes vital
respiratory surfaces or across the skin organs of the body and the brain. The
through sweat glands. Animals with fur regulation of skin temperature involves
such as cattle, dogs, and birds have limited four major components: the set point,
ability to sweat; therefore, they rely on detector, comparator or regulator, and
corrective mechanism. First, the set point
panting to increase evaporation of water is the favourable skin temperature or
across the moist surface of their tongues the temperature at which an individual
and mouths.
feels comfortable and relaxed. Second,
the detectors are the thermo-receptors

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