• Digestion begins with the mechanical grinding of food by teeth in the mouth and the chemical breakdown of starch in foods by enzymes in saliva secreted by salivary glands.
• With the help of the tongue the bolus (the soft mass of food) is moved to the pharynx and then to the to the stomach via the esophagus.
• In the stomach food is mechanically churned and chemically broken down further by the action of acids and enzymes.
• The acids and enzymes here start the digestion of proteins.
• The acid in the stomach also protects the body against bacterial invasion.
• The main function of the stomach is to store food for a brief time and move it into the intestines in small amounts after it is liquefied.