2 - HUMAN NUTRITION 

Digestive enzymes 

• Break down big molecules into smaller ones 
• Starch, proteins and fats are too big to pass through walls of digestive system and insoluble 
• Sugars, amino acids, glycerol and fatty acids are smaller, soluble and can pass through walls of digestive system 

Amylase - starch to maltose 

Maltase - maltose to glucose 

Protease(s) - proteins to amino acids 

Lipase(s) - lipids to glycerol and fatty acids 

Bile - 

• Produced in liver, stored in gall bladder, released into small intestine 
• Neutralises stomach acid 
• Emulsifies fats 
• HCl in stomach makes pH too acidic for enzymes in small intestine - bile neutralises/makes conditions alkaline 
• Emulsifies fats - breaks fats into tiny droplets (bigger surface area for lipase to break down - speeds up digestion)