Health qi is energy of human life, if you have qi you will be existence but not you will be dead. So-called health qi is relatively speaking to evil qi. Contents of health qi is widespread, changes of materials foundation of human body function pertain to health qi, such as medical physiology, biophysics, biochemics. Denominations of health qi are various and production and roles of qi are different, it generally can be divided into below categories.

The first category: health qi that comes to extraorgan
Airborne qi includes oxygen in air which is absorbed by lung, light rays (ultraviolet rays, infrared rays) which are received by skin, heat which is received by mouth and skin, beneficial contribution that celestial body has to.

Earth qi includes nutritional ingredient and moisture content which are in food stuff, microelement and geomagnetism which are benefit to human body; it is called essential substances from water and cereals.

Qi of Airborne and earth are essential to human existence and sources of qi of postnatal life.

The second category: health qi in human body
Source qi is first formed in embryon and comes from parents then grows up in embryon generally; it is combination of acquired qi and motivation of qi transformation.

Essential qi is quintessence qi of human body, quintessence parts of every qi are called essential qi, but essential qi is main qi of potentia generandi.

Spirit qi is composed by innate qi and viscera and bowels qi and expresses mental status. The heart stores the spirit, lung storing soul, lung storing soul, spleen storing will and kidney controlling aspiration which are recorded in Suwen, Xuanmingwuqipian pertain to spirit qi.

Genuine qi which is normal existence of human body is combined by airborne qi, earth qi and source qi and supports function activity of body. Genuine qi is generic name of postnatal function activity and it includes ancestral qi, nutrient qi and defense qi.

Ancestral qi is combined by airborne qi, earth qi and source qi. It is in chest and it does not circulate along meridians. Roles of ancestral qi is to impulse circulation of qi and blood, qi that partakes circulation of meridians and collaterals such as nutrient qi and defense qi circulates through driving force of ancestral qi.

Nutrient qi which is transformed by genuine qi and contains nutritional ingredient and runs through meridians and vessels is main qi in circulation of meridians qi. It circulates fifty circuits in body everyday and nourishes the whole body.

Defense qi is transformed by genuine qi and has defense competence. It circulates between yang meridians at day and circulates between yin meridians at night and defenses human body around the clock to prevent invasion of exogenous evil. Besides it warms and nourishes viscera and bowels and warms and moistens muscle and skin.  
 
Qi of viscera and bowels are started by each viscus and bowel and circulates in their meridians and collaterals and meridians and collaterals in internal and external relation then supports regular meridian and organism and organs that meridians in internal and external relation administer, it transports qi to relevant viscera along distribution of meridian and collateral of viscus and help qi transformation.

Blood which is blood in human body is transformed by genuine qi and circulates in blood vessels. Operation of blood is promoted by qi; blood and qi are two materials, blood is materiality and qi is invisible and blood can play roles in qi.

Qi of above acts in meridians and collaterals and is called meridian qi. These qi is qi of functional activity of human body, so it is called health qi of human body that is qi of human body activity.