Introduce the general idea: human body need all kinds of nourishment during the life(such as water, inorganic acid, protein, glycolipin, microbian mineral, oxygen),blood cycle for digestion.

人体在命运中需要各种营（、机盐、蛋白质、糖类脂肪、维物矿物质，氧气），其消化吸收需通血液循环系统。