(1) Propelling function
Qi is a refined element with vitality. Like an energy source, it activates and promotes the body’s growth and development, motivates or drives the physiological functions of all the organs, and promotes the generation and circulation of Blood, and the production, distribution, and excretion of Body Fluid. Qi is called the “root of life.” The Basic Questions says, “A human being results from the Qi of Heaven and Earth …. The union of the Qi of Heaven and Earth forms human beings” . Qi functions differently in different viscera and organs. For instance, Blood circulation is propelled by Qi. If Qi action is weak, it will lead to dysfunction of the whole body.
(2) Warming function
Qi is the body’s heat energy source. Yang-Qi from Kidney-Yang and Spleen-Yang maintains normal body temperature and ensures the physiological function of all viscera and organs. All five Zang organs have Yang-Qi. If Yang is deficient, Qi’s warming function is weakened, and may result in cold limbs, intolerance of cold, sluggish circulation, stagnation and internal cold, and even dysfunction of the viscera. The failure of Qi to warm the body is the source of most illnesses. Conversely, Qi stasis may result in Heat, appearing as fever.
(3) Defending function
Qi, especially Yang-Qi, protects the body and resists the attack of exogenous evils. Defensive-Qi (Wei-Qi) resists the invasion of pathogens and prevents disease. This includes functions to protect the whole body against pathogen invasion and disease onset, and the ability to drive out the pathogens to cure disease. If Qi’s defending function weakens, immunity functions decline.