Digestion

• digestion: the process of breaking down food into smaller pieces so that it can be absorbed into the bloodstream
• protein in the stomach: brown down by the stomach into simpler substances called amino acids and peptides
• protein in the small intestine: absorbed through the walls of the small intestine
• carbohydrates in the mouth: broken down into simple sugars (monosaccharides) by salivary enzymes, such as amylase.
• carbohydrates in the small intestine: further breakdown occurs with the addition of pancreatic amylase from the pancreas and disacharidases from the brush border membrane of the epithelial cells lining the small intestine
• carbohydrates in the stomach: not digested because there are no digestive enzymes present
• fats in the small intestine: digested by lipase to form fatty acids and glycerol which are then absorbed into the blood stream via the lacteal vessels
• lipids in the small intestine: fatty acids and glycerol are released from triglycerides by lipase and then transported across the wall of the small intestine into the lacteals
• mouth mechanical: teeth chew food and break it down into a mush known as the bolus, the food travels down the osophegas via peristalsis
• mouth chemical: saliva contains the enzyme amylase which breaks down starch into simple sugars
• stomach mechanical: churning motion mixes food with gastric juices and propels it towards the duodenum, the walls contract rhythmically to push the contents around (peristaltic movement)
• Stomach chemical: gastric juices break down the food until it becomes a thick liquid known as chyme
• small intestine mechanical: peristalsis moves the chyme through the small intestine as well as the villi. nutrients are absorbed by the villi
• small intestine chemical: pancreatic enzymes and bile are secreted from the pancreas and gall bladder into the small intestine where they work to further break down food
• large intestine mechanical: the remaining cellulose is pushed through the large intestine
• large intestine chemical: production of vitamins, digestion of fibre resistant starch
• Anus: opening at end of rectum that allows passage of faeces out of body