There are three levels in classical Traditional Chinese physiology:
The external level of the 12 meridian channels, which maintain the balance within the organism and between the organism and its environment. These channels are considered prone to attack by environmental factors, such as: Wind, Cold, Damp, Dust and Heat. Problems at this level tend to be of an acute nature, and are relatively easy to cure.
The deep level, here are the 12 organs which are
classified into 5 elements, namely Fire, Earth, Metal,Water and Wood.
Fire contains the Heart, which is encased in the
Pericardium, and the Small Intestines which are encased
in the Triple Warmer. The organs of this element
control the tongue, brain, circulation of blood, Qi and
essences.
Earth contains the Spleen and Stomach organs, this
element controls the mouth, ingestion, digestion,
absorption, assimilation, utilisation and secretion. It
also pertains to fluid control and soft tissues.
Metal contains the Lung and Large Intestine organs,
this element controls the nose, sinuses, skin, skin
hair, lungs, and large intestine.
Water contains the Kidney and Bladder organs, this
element controls the ears, bones, joints, cartilage,
head hair, genitourinary organs and of course the
kidneys and the bladder.
Wood contains the Liver and Gallbladder organs, this
element controls the eyes, muscles, tendons and liver
and gallbladder.
The internal organs are attacked by the internal causes,
which usually refers to damage caused by an excess of the
five emotions: Excitement or joy, sympathy, grief, fear
or shock and anger. The internal organs are also affected
by unhealthy food and a bad lifestyle. Diseases of the
internal organs are more difficult to cure than diseases
of the 12 channels.
Between the internal organs and the 12 channels is an
intermediate area which according to Traditional Chinese
Medicine is composed of a network of deep energy channels
and the 5 groups of tissues: Blood, Qi and essences; soft
tissues and fluid, skin and skin hair; bones, joints,
cartilage and head hair, and muscles and tendons.