Technical
hairy protrusions. Together with the mucous
membranes, these cilia form the respiratory
epithelium. It is constantly in motion and is often
compared with a field of corn stalks swaying in the
wind. This constant motion ensures that impurities
and disease-causing agents inhaled in the air we
breathe are blended with mucous and then carried
away before an infection can occur. Like an air-
conditioning system, our nose cleans the air, heats
it to 37°C and ensures a 100% humidification and
steam saturation. This is the only way the air can
access our alveoli. Otherwise oxygen absorption
would not be possible.
Breathing in excessively dry air compromises the
functioning of the respiratory epithelium. The mucous
no longer obtains enough water and moisture and as
a result thickens, no longer runs off and breaks down.
The self-cleaning effect only works inadequately. This
opens the floodgates for viruses and bacteria. Our
immune defence therefore needs optimum moisture
conditions for us to stay healthy.
Skin: With a surface of about 2m², the skin is our
largest organ. It protects us from cold, heat and
radiation, offers resistance to pressure and impact,
with its slightly acidic pH value of 5.7 keeps germs and
microorganisms at bay, and is our primary item of
clothing for heat insulation. Its structure can be seen
under the microscope.
There are three layers: The epidermis with a corneal
layer, the dermis and the subcutaneous layer. The skin
is also our largest sensory organ, supports breathing
and is cooling when we perspire. All in all, the skin is
multi-functional, combines water and fat tissues and
provides an external barrier. If the ambient conditions
are right, it remains elastic as it does so.
However, if the skin loses moisture and fats, this
barrier crumbles. Dry ambient air may favour this
process, if the body itself can no longer obtain enough
from inside to compensate. This can be the case in sick
or older people especially. The same goes for infants
whose skin is not yet fully formed. In these cases, the
corneal layer becomes increasingly porous and loses its
protective function more and more. At the same time,
dangerous substances can penetrate more easily which
leads to skin irritations and inflammations. RACA
To be continued … in an upcoming edition of RACA
Journal.
www.hvacronline.co.za
RACA Journal I January 2019
79