写在前面的话人体消化系统是由长约8～10米的消化道(由口、咽、食管、胃、小肠、大肠、肛管及肛门组成)和附属消化腺(唾液腺、胃黏膜及小肠内腺体、肝、胆、胰腺等)组成。其主要功能是摄取、消化和吸收食物,为机体提供生长、发育和新陈代谢所需要的物质和能量来源。通 Write in front of the human digestive system is composed of the digestive tract of about 8 to 10 meters (composed of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, anal canal and anus) and the accessory digestive gland (salivary gland, gastric mucosa and small intestine Gland, liver, gallbladder, pancreas, etc.). Its main function is to ingest, digest and absorb food, providing the body with the material and energy sources needed for growth, development and metabolism. through