how is desigend disegestive system?

In thehuman digestive system, the process of digestion has many stages, the first of which starts in themouth(oral cavity). Digestion involves the breakdown of food into smaller and smaller components which can be absorbed and assimilated into the body. The secretion ofsalivahelps to produce aboluswhich can be swallowed to pass down theoesophagusand into thestomach.
Saliva also contains acatalyticenzymecalledamylasewhich starts to act on food in the mouth. Digestion is helped by the masticationof food by theteethand also by themuscular contractionsofperistalsis.Gastric juicein the stomach is essential for the continuation of digestion as is the production ofmucusin the stomach.
Peristalsis is the rhythmic contraction ofmusclesthat begins in the oesophagus and continues along the wall of the stomach and the rest of thegastrointestinal tract. This initially results in the production ofchymewhich when fully broken down in thesmall intestineis absorbed aschyleinto thelymphatic system. Most of the digestion of food takes place in the small intestine. Water and some mineralsare reabsorbed back into the blood, in the colon of thelarge intestine. The waste products of digestion aredefacatedfrom theanusvia therectum.