Qi or Chi
The character qi denotes a dynamic essence characterized by both
substance and function. For example, clean qi, turbid qi, and the
qi transformed from the essence of food are substantial qi,
while the qi of the heart, liver, spleen, kidney, stomach, and
the qi of the channels and collaterals are functional qi.
The classification of qi in the human body varies with its
distribution, origin, and function.
1. Primary Qi (yuan qi)
Primary qi is the most important and fundamental qi originating
from the congenitalessence. It is nourished and replenished by the
fundamental substance of food after birth. Primary qi is also known
as the qi of the kidney, and is distributed to the whole body via the
sanjiao functions. It arouses and promotes the activities of the
zang-fu organs and tissues. If primary qi is congenitally deficient
or exhausted due to chronic disease, then various pathological changes
2. Aggregative Qi (zong qi)
This is the combination of inhaled clean qi through the lung with
the fundamental substance qi of food digested and absorbed by the
stomach and spleen. Aggregative qi is accumulated in the chest and
has the function of nourishing the lung and the heart, thus
promoting respiration and blood circulation.
3. Nutrient Qi (ying qi)
Nutrient qi originates from the essential substance of food
transformed by the spleen and stomach. It is the component part
of blood flowing throughout the body. The Suwen states, "Nutrient
qi is actually the essential qi transformed from food and water."
While in the Lingshu it is recorded:
The nutrient qi is secreted by the body fluid, circulates in the
blood vessels, and is transformed into blood to nourish the four
extremities, the five zang and six fu organs.
4. Defensive Qi (wei qi)
Defensive qi is mainly derived from the essential substances of food
and water which form a part of the human body's yang qi. It
circulates outside the vessels mainly spreading through the muscles
and skin. Its physiological functions are (1) defending the body
surface against the invasion of exogenous pathogenic factors,
(2) warming and nourishing the tissues and organs, and (3) adjusting
the opening and closing of the pores.