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Regulation

the superficial arterioles dilate in order to allow blood to flow close to the skin surface.
Heat from the blood is conducted through the lower epidermis to the skin surface where
it is radiated away from the body. See Figure 5.6.

More sweat
Heat loss by radiation
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Dilated blood
vessel,

Sweat gland
produce sweat Subcutaneous
fat layer
Figure 5.6: Vasodilation
Panting and licking: These are mechanisms in which an animal passes the tongue over
for reducing body temperature in canids, its body surface to spread saliva. This in
the dog family and in birds. Panting is a turn provides the means of evaporative
thermoregulatory mechanism in which cooling. Licking is common in animals
an animal breathes with short, rapid and that do not sweat instead they make use
quick gasp with its mouth open and tongue of their saliva to cool their bodies. Rabbits
hanging out. When a bird pants, it breathes for example, lick their front legs and chest,
quickly with the mouth wide open. This cats lick their front paws and spread saliva
allows air to move across the moist surface across the ears.
of its lungs, throat and mouth. The moisture
then evaporates, and it absorbs heat from
the bird’s body. Dogs do not have sweat
glands over most of their skin. Sweat glands
in dogs are only found in the pads of their
feet and nose. During panting, a dog hangs
out its tongue (as seen in Figure 5.7) and
water evaporates from the surface of the
tongue and nose. As a result temperature
of its body is cooled. Opening the mouth
provides a large surface area for heat loss Figure 5.7: Panting in dog
in these mammals. Some animals lick their Body extremities: Body extremities are
bodies to deposit saliva onto their body external body parts of an organism such
surface. Licking is the natural behaviour as limbs, ears, tails, genitalia and antennae.

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