http://www.ck12.org Chapter 1. Human Biology
1.17 Enzymes in the Digestive System
- Explain the role of enzymes in digestion.
What happens if you suck on a piece of white bread?
If you kept a bite of white bread in your mouth for a long period of time, it would start to get really mushy. Then it
would start tasting sweet. That’s because you have enzymes in your saliva. The enzymes break down the complex
carbohydrates in the bread into simple sugars.
The Role of Enzymes in the Digestive System
Chemical digestion could not take place without the help of digestive enzymes. Anenzymeis a protein that speeds
up chemical reactions in the body. Digestive enzymes speed up chemical reactions that break down large food
molecules into small molecules.
Did you ever use a wrench to tighten a bolt? You could tighten a bolt with your fingers, but it would be difficult and
slow. If you use a wrench, you can tighten a bolt much more easily and quickly. Enzymes are like wrenches. They
make it much easier and quicker for chemical reactions to take place. Like a wrench, enzymes can also be used over
and over again. But you need the appropriate size and shape of the wrench to efficiently tighten the bolt, just like
each enzyme is specific for the reaction it helps.
Digestive enzymes are released, or secreted, by the organs of the digestive system. Examples of digestive enzymes
are:
- Amylase, produced in the mouth. It helps break down large starch molecules into smaller sugar molecules.
- Pepsin, produced in the stomach. Pepsin helps break down proteins into amino acids.
- Trypsin, produced in the pancreas. Trypsin also breaks down proteins.
- Pancreatic lipase, produced in the pancreas. It is used to break apart fats.