Differences between chemical & mechanical digestion

Written by daniel zimmermann
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Differences between chemical & mechanical digestion
Teeth affect mechanical digestion. (mouth image by JASON WINTER from Fotolia.com)

Digestion takes place in the alimentary canal, which consists of the mouth, the oesophagus, the stomach, the small intestine and the large intestine. Two types of digestion occur within this alimentary canal: mechanical digestion and chemical digestion. These two digestive processes differ from one another in several ways.

Different Principal Sites

Mechanical digestion takes places chiefly in the mouth, and to a lesser extent, the stomach, while chemical digestion takes place principally in the stomach and secondarily in the mouth and the intestines, according to the Tempe, Arizona Union High School biology curriculum.

Different Agents

The teeth are the principle agents of mechanical digestion. The smooth muscles of the stomach and other parts of the alimentary canal also effect mechanical digestion. Enzymes secreted in the stomach and elsewhere bring about chemical digestion. Pepsin, trypsin and rennin are three such enzymes. The stomach also contains a small amount of hydrochloric acid, another agent of chemical digestion.

Different Energy Modes

Mechanical digestion affects digestion through mechanical energy, such as the force and motion involved in chewing and the peristaltic action of the intestines, which is a sort of wavy movement of the intestine walls. Stomach muscles also agitate the food. Chemical digestion uses chemical energy stored in the enzymes to execute its digestive operations.

Different Effects

Mechanical digestion effects physical changes. For example, chewing converts a large piece of food into smaller pieces. Chemical digestion brings about chemical changes. For example, pepsin converts proteins into smaller units called peptides, and trypsin changes the peptides into even smaller organic molecules called amino acids. Other chemical reactions convert starches and complex sugars into simple sugars such as glucose while the enzyme lipase digests fats, converting them into carbohydrates and a simple organic molecule called glycerol, according to the educational website, the Soaring Sphincter Travel Agency.

Different Digestive Roles

The action of mechanical digestion makes chemical digestion easier, while chemical digestion makes it possible for the body to absorb nutrients.

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