Bioenergetics: Digestion

Digestion: Definition and Purpose

Digestion is the process where food is broken down into simple soluble substances that can be absorbed by the body.
The process of digestion takes place in the digestive system, which is a complex series of organs stretching from the mouth to the anus.
Its purpose is to break down complex food substances into smaller molecules that can be absorbed into the bloodstream and used by the body.

Physical digestion involves the physical breaking down of food into smaller pieces. It begins in the mouth with the process of chewing.
Following the physical breakdown, chemical digestion begins where large molecules are broken down into more simple ones through the use of enzymes.

Mouth: Digestion begins with the physical breakdown of food by teeth and the enzymatic action of saliva on starch.
Oesophagus: Uses muscular contractions, called peristalsis, to move food into the stomach.
Stomach: Further physical digestion occurs here through churning and mixing actions. Proteins are also chemically broken down by stomach acid and pepsin, an enzyme.
Small intestine: Majority of chemical digestion and absorption happens here. Pancreatic enzymes and bile from the liver aid in digestion, and nutrients are absorbed via villi into the bloodstream.
Large intestine (colon): Water and electrolytes are absorbed here. Undigested food is formed into faeces for expulsion.

Amylase: produced in the salivary glands, pancreas and small intestine, it breaks down starch into maltose.
Protease: produced in the stomach, pancreas and small intestine, this enzyme breaks proteins down into amino acids.
Lipase: produced in the pancreas and small intestine, it breaks down fats into glycerol and fatty acids.

Diet: Balanced diet containing essential nutrients, fiber and adequate water promotes healthy functioning of the digestive system.
Fitness level: Regular exercise may help stimulate productive digestion and help maintain bowel regularity.
Hydration: Adequate fluid intake can aid in maintaining a healthy digestive system by preventing constipation.