enzymes and digestion

• starch, proteins and fats are BIG molecules. they're too big to pass through the walls of the digestive system so digestive enzymes break these BIG molecules down into smaller ones like sugars, amino acids, glycerol and fatty acids. these smaller, soluble molecules can pass easily through the walls of the digestive system, allowing them to be absorbed into the bloodstream
• amylase is an example of a carbohydrate. it breaks down starch
• amylase is made in the salivary system, pancreas and small intestine
• proteases are made in the stomach, pancreas and small intestine
• lipases are made in the pancreas and small intestine
• the products of digestion can be used to make new carbohydrates, proteins and lipids
• bile is produced in the liver. it's stored in the gall bladder before it's released in the small intestine
• the hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. bile is alkaline - it neutralises the acid and makes conditions alkaline. the enzymes in the small intestine work best in these alkaline conditions
• bile breaks down the fat into tiny droplets. this gives a much bigger surface area of fat for the enzyme lipase to work on - which makes its digestion faster
• salivary glands - these produce amylase enzyme in the saliva
• liver - where bile is produced. bile neutralises stomach acid and emulsifies fats
• large intestine - where excess water is absorbed from the food
• rectum - where the faeces are stored before they go through the anus
• small intestine - produces protease , amylase and lipase enzymes to complete digestion, this is also where food is absorbed out of the digestive system into the blood
• pancreas - produces protease, amylase and lipase enzymes. it releases these into the small intestines
• stomach - pummels the food with its muscular walls, produces the protease enzyme (pepsin) and produces hydrochloric acid for two reasons (it kills bacteria, to give the right pH for the protease enzyme to work)