Process

2.4.2 Enzymes

2.5 Nervous coordination

Process

  1. Role

    1. Starch, proteins and fats are insoluble so are broken down into soluble substances to be absorbed into the bloodstream through the wall of the small intestine
    2. In the large intestine, much of the water mixed with the food is absorbed into the bloodstream
    3. The remaining indigestible food makes up the bulk of faeces, which leave the body through the anus

  2. Digestive juices

    Substance Production location Role
    Amylase Salivary glands
    Pancreas
    Small intestine    		 Catalyses the breakdown of starch into sugars in the mouth and small intestine
    Protease Stomach
    Pancreas
    Small intestine    		 Catalyses the breakdown of proteins into amino acids in the stomach and small intestine
    Lipase Pancreas
    Small intestine    		 Catalyses the breakdown of lipids into fatty acids and glycerol in the small intestine
    Hydrochloric acid Stomach Provides an acidic environment where enzymes in the stomach work most effectively
    Bile Liver; stored in the gallbladder; released into the small intestine Provides an alkaline environment where enzymes in the small intestine work most effectively
    Emulsifies fats, increasing the surface area for lipase to act on