消化系统是有关摄取和吸收食物以及排泄未吸收的残渣的一组器官。食物具有多种不的类型。可能是湿的、干的、固体或液体状的,且由不同的化学成分组成。食物在被机体利用以前,必须通过机械的和化学的作用,以使其转变为易吸收的形式。这些机械和化学变化的过程称为消化。 The digestive system is a group of organs that take in and absorb food and excrete unabsorbed residue. Food has many different types. It may be wet, dry, solid or liquid and consist of different chemical constituents. Before the food can be used by the body, it must be mechanically and chemically transformed to make it into an easily absorbed form. These mechanical and chemical changes are called digestion.