Summary
Highlights
Large molecules like carbohydrates, proteins, and lipids are too big to be absorbed into the bloodstream across the villi of the small intestine. Enzymes, which are special proteins, speed up chemical reactions to break these large molecules into smaller, soluble pieces.
Carbohydrates, such as starch (a polymer of glucose), are broken down in a two-step process. First, amylase breaks starch into maltose. Then, maltase breaks maltose into glucose, which is small enough for absorption. Enzymes often end in '-ase'.
Proteins are broken down by protease enzymes into amino acids. Protease is a group of enzymes that includes specific types like trypsin and pepsin.
Lipids (fats and oils) are broken down by lipase enzymes into glycerol and fatty acids. Bile, though not an enzyme, aids in lipid digestion by emulsifying large lipid droplets into smaller ones, increasing the surface area for lipase to act upon.
All three types of enzymes (amylase, protease, lipase) are produced by the pancreas and the small intestine. Amylase is also made by the salivary glands in the mouth, and proteases are additionally produced by the stomach.