Enzymes and Digestion Unit 2.1

Enzymes and Digestion

Learning Objectives:

• What are the structure and function of the major parts of the digestive system?
• How does the digestive system break down food both physically and chemically?
• What is the role of enzymes in digestion?

The digestive system is made up of a long muscular tube and its associated glands. The glands produce enzymes that break down large molecules into small ones ready for absorption. The digestive system provides an interface with the environment as food substances enter the body through it.

Major parts of the digestive system:

• The oesophagus carries food from mouth to stomach. Therefore adapted for transport rather than absorption or digestion; hence made up of a thick muscular wall.
• The stomach is a muscular sac with an inner layer that produces enzymes. Its role is to store and digest food, especially proteins. It has glands which produce enzymes to digest proteins. Other glands in the stomach wall produce mucus. This is to prevent the stomach being digested by its own enzymes.
• The small intestine is a long muscular tube. Food is further digested in the small intestine by enzymes produced by its walls and by glands that pour their secretions into it. The inner walls of the small intestine are folded into villi, which gives them a large surface…