Answer:

Process of digestion of food: Ingestion - Digestion - Absorption - Assimilation.

Explanation:

Digestion is a process of breaking down complex food materials into simpler forms with the help of enzymes. The enzymes used in digestion are called digestive enzymes. The digested food is in a simpler form and is easily absorbed by the body.

Digestion of food in the mouth:

• The buccal cavity performs two major functions, mastication of food and facilitation of swallowing. The teeth and the tongue with the help of saliva masticate and mix up the food thoroughly. Mucus in saliva helps in lubricating and adhering the masticated food particles into a bolus.
• The bolus is then conveyed into the pharynx and then into the esophagus by swallowing or deglutition. The bolus further passes down through the esophagus by successive waves of muscular contractions called peristalsis.
• The gastro-oesophageal sphincter controls the passage of food
• into the stomach. The saliva secreted into the oral cavity contains
• electrolytes and enzymes, salivary amylase and lysozyme. The chemical process of digestion is initiated in the oral cavity
• by the hydrolytic action of the carbohydrate splitting enzyme, the salivary

Digestion of food in stomach and intestine:

• Chemical digestion of protein begins in the stomach and ends in the small intestine.
• The stomach releases gastric juices containing hydrochloric acid and enzyme pepsin which supports the breakdown of protein.
• The pancreatic and bile juice is poured into the small intestine of the digestive system.
• The bile juice makes the food alkaline and is involved in the digestion of fat molecules.  The pancreatic juice contains trypsin which breaks down protein.  
• The large intestine mainly absorbs water from the undigested food.
• The undigested waste matter which reaches the rectum after the absorption of water is semi-solid.

A diagram showing digestion process is: