First point is to understand the digestion, it is a process in which food is breakdown into smaller components that can be easily observed and assimilated.
There are two Processes Involved in Digestion:
1. Mechanical Process
It is a physical breakdown of food into smaller pieces, which can be easily accessed by the digestive enzymes. The mechanical process occur in mouth by the action of mastication. During mastication, food is also mixed with saliva, in which salivary amylase is found that catalyzes the starch. Thereafter, the food turned into small, round slurry mass called, bolus. Bolus, then enters into stomach through esophagus.
2. Chemical Process
After entering the bolus into stomach, the food is treated with various gastric juices. The gastric juices mainly contain; hydrochloric acid and pepsin. These gastric juices digest the proteins and could change the wall of stomach. Therefore, stomach secrets mucous to protect their membrane. The digested food is retained in stomach for 1-2 h, which is called as chyme, then passed to duodenum followed by intestine and further digestion process is done.