Process of prenatal development:
According to record of Lingshu.Tiannian, in process of embryo, human body first is combination of yin and yang qi (process of fertilization) and then breeds (form embryo). Embryo first produces blood in growth (first form meridians and vessels) and receives nutrient qi and defense qi which is in mother nuclide in process of formation of meridians and vessels. After connection of qi and blood, embryo devels into figure of human and has competence of activity, it becomes human when soul and spirit are perfect. It emphasizes here function of nutrient qi and defense qi. Nutrient Qi and blood and defense qi and blood depends meridians and collaterals running, it illustrates that first forms in embryo are meridians and collaterals and it is only meridians and collaterals appear that nutrient Qi and blood and defense qi and blood can play role. Meridians and collaterals are main element that urges embryonic development.

Process of acquired growth:
When human were born and breathe at the first time, he breathes in airborne qi (oxygen) and eats then produces genuine qi and forms his own meridians and collaterals circulation of nutrient qi and defense qi, then he grows in nature. After born, system of meridians and collaterals are formed initially but not consummation and some meridians and collaterals do not become prosperous, especially meridians and qi of some viscera and bowels are in process of formation. So maturity of human needs development process some times when viscera of meridians and qi develop magnificent. It is after developed of meridians and collaterals completely that human enters into stage of ripeness. Conception vessel and thoroughfare vessel are easy and smooth when 14 years old and kidney qi of kidney meridian develops perfect state at 21 years old.

Aging process of human body:
Aging degree and aging process of human after maturity are depended on transport capacity of meridians and collaterals to qi and prosperity degree of qi and blood. Inhibited of meridians and collaterals and debilitation of qi and blood are symbol of aged. Conception vessel is deficiency, Taichong meridian is weak, menstruation exhausts and female genital duct is impotency at 49 years old. There is record in Lingshu.Bencang that if meridians and collaterals are easy and smooth, five viscera and six bowels will disease of pathogenic factors. It summarizes function of meridians and collaterals and qi and blood in physiology of human body.