The breakdown of large insoluble molecules into small soluble ones that can be absorbed and utilized by the body
Enzymes
Secreted by glands to break down solid food into a solution of dissolved particles that are small enough to pass through the epithelial lining of the small intestine and into the bloodstream
Enzymes involved in chemical digestion
Amylase
Proteases
Lipase
Amylase
Breaks down the complex carbohydrate starch into simple reducing sugars
Amylase action
1. Produced by salivary glands and released into the mouth
2. Continues in the duodenum (first part of small intestine) in pancreatic juice
Proteases
A group of enzymes that chemically digest large insoluble proteins into amino acids
Protease action
1. Secreted in gastric juice by glands in stomach lining
2. Continues in duodenum by proteases in pancreatic juice
3. Finalized in ileum by enzymes in epithelial cell membranes
Lipase
Breaks down fat molecules called triglycerides into soluble fatty acids and glycerol
Lipase action
Produced in pancreas and acts in the duodenum
Starch digestion
1. Stage 1: Amylase in mouth and duodenum breaks down starch into maltose
2. Stage 2: Maltase in ileum breaks down maltose into glucose
Protein digestion
1. Pepsin in stomach breaks down proteins into peptides
2. Trypsin in duodenum further breaks down peptides
3. Peptidase in ileum breaks down peptides into amino acids
Acidic stomach contents
Bile from gallbladder neutralizes to allow enzymes in duodenum to function optimally
