Process of Digestion

Science, Grade 6


Table Of Contents: Process of Digestion

1. Mechanical Digestion
Food is broken apart physically to make it easier for chemical digestion to occur. This process starts with chewing our food and mixing it with saliva and is followed by a physical churning that takes place in the stomach.
2. Chemical Digestion
Food is chemically digested by enzymes that break chemical bonds between food molecules. This process makes food molecules less complex and easier to absorb. Chemical digestion of carbohydrates begins in the mouth with the release of the enzyme amylase within the saliva. Chemical digestion of proteins starts in the stomach. The majority of chemical digestion, however, occurs in the small intestine.
3. Digestive Enzymes
Enzymes released by glands of the digestive tract, such as the salivary glands, pancreas and the intestines, act to break down large molecules into their simplest forms.
4. Pancreatic Enzymes
The greatest number and variety of digestive enzymes are released by the pancreas. Pancreatic enzymes digest carbohydrates, proteins and lipids in our foods. Carbohydrates are broken down to simple sugars, and proteins are broken down to amino acids. Fats are broken down to triglycerides and fatty acids. These end products of digestion can then be absorbed in the body to sustain life.
5. Absorption of Nutrients
End products of digestion and many other molecules, including water, are absorbed through the lining of our digestive tract into the bloodstream. Most of this absorption happens within the small intestine. These nutrients are transported to vital organs in support of body functions and other chemical reactions.