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The skin has several
functions to perform. It regulates the body temperature and protects
underlying tissue from injury and infection. The skin can synthesize
vitamin D when exposed to light. This is a minor function and its
mechanism is not yet fully understood. The skin produces new cells
continually and when the new cells appear, the old ones wear away
from the skin.
The human body is
continuously kept in a stable condition mainly through the function
of the autonomic nervous system and the body’s hormones. The medical
term for this is maintaining “homeostasis”. Whatever the climatic
conditions, this keeps the body at a constant temperature of about
37°C.
In cold weather, the
body needs extra heat and it generates as much heat as necessary by
causing muscles to contract into spasms, which are better known as
shivers. That is why human beings maintain the same body temperature
irrespective of the air temperature outside. In fact, most animals
and birds too maintain their body temperature. These animals are
said to be warm blooded. A few creatures, such as lizards and
snakes, however, lose body heat when the air is cold and they go to
sleep till it gets warm again.
When it is cold, our
hair stands up straight. The skin around each hair swells and closes
the pore so tightly so that the heat inside the body cannot escape.
When the body is cold, a tiny muscle at the base of each hair
contracts, making the hair stand on end, producing gooseflesh. In
ancient times, when people had too much hair on their bodies, they
would fluff it up to keep their bodies warm. Today, people do not
have so much hair, but the skin pores around the strands contract
and cause gooseflesh to happen.
Well, what happens when
the body is too hot? The sweat glands secrete sweat, a mixture of
water and waste products. As the sweat evaporates from the skin’s
surface, it uses heat from the body, thus causing it cool down. |
