The sebum
serves as lubricant. It is generally discharged near or at the shaft of
a hair.
The sweat glands discharge on the average from one and one-half to two
pounds of perspiration per day, more in hot weather and much less when
it is cool. They are distributed over the whole external surface of the
body. According to Krause there are almost 2,400,000 of them. They carry
off water and carbonic acid gas chiefly.
The functions of the skin are: To protect the underlying structures; to
regulate the heat; to serve as an organ of respiration; to serve as an
organ of touch and thermal sensation; to secrete and eliminate various
substances from the body; to absorb.
The heat regulation is quite automatic. When the external temperature is
high there is a relaxation of the skin. The pores open, the perspiration
goes to the surface and evaporates, thus cooling the body. When the
surface is cool the skin contracts, closing the pores and conserving the
heat. Radiation always takes place, except when the temperature is very
high.
The sensation of touch and the ability to feel heat and cold protect us
from untold numbers of dangers. They are a part of the equipment which
enables us to adjust our selves to our environment.
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