02 The Digestive system

Learning objectives:

• • State the names of key body organs that make up the digestive system. Label them on a diagram and describe their functions

  • describe the different stages in the process of digestion

  • Compare mechanical and chemical digestion

  • Explain the role of enzymes in digestion.

  • Outline how Amylase helps to break down starch into smaller glucose molecules that can then pass into the blood-stream through the walls of the small intestine.

  • Outline how Protease helps to break down protein into smaller amino acid molecules that can then pass into the blood-stream through the walls of the small intestine.

  • Outline how Lipase helps to break down lipids into smaller fatty acid and glycerol molecules that can then pass into the blood-stream through the walls of the small intestine.

  • Explain how the Villi lead to an increased rate of absorption in the small intestine

  • State that enzymes work best at an optimum temperature and pH level.

Structure and function:

You will need to learn the names of the parts of the digestive system. Use this information to complete the labelling exercise below.

The functions of the parts of the digestive system can be found in the video below and also by using the interactive site shown above.

The process of digestion can be reviewed here:

Use Quizlet to make a set of revision cards to help you to learn the functions of the parts.

Digestive enzymes:

Chemical digestion is carried out by digestive enzymes. There are 3 min ones that you need to familiarise yourselves with: Lipase, protease and amylase. See the video and mind map shown below for information about these, then complete the summary sheet.

Absorption into the blood:

The digested food will be absorbed into the blood in the ileum. This has structures called villi on the surface in increase the surface area for absorption. Click below for more information about this. 

You will carry out a practical using visking tubing to investigate whether starch and/or glucose can move through the wall of the small intestine. 

Try to answer these questions after you have done it to practice applying your knowledge.