Digestive enzymes

• Digestion involves the breakdown of large insoluble molecules into soluble substances that can be absorbed into the blood across the wall of the small intestine
• Digestive enzymes are produced by specialised cells in glands and in the lining of the digestive system
• Carbohydrases such as amylase (which breaks down starch) catalyse the breakdown of carbohydrates to simple sugars
• Proteases catalyse the breakdown of proteins into amino acids
• Lipase catalyse the breakdown of lipids to fatty acids and glycerol
• Bile produced in the liver is stored in the gall bladder and is released through the bile duct into the small intestine. It has two functions:

  • it neutralises the stomach acid and makes the small intestine alkaline
  • It emulsifies fats, which means it breaks down large fat droplets into smaller ones to increase the surface area. This speed up the breakdown of lipids by lipase into fatty acids and glycerol