O O Digestion is the breakdown of nutrients into simpler substances that can be absorbed into the bloodstream and used by the body to keep us alive and healthy.
O O Food is broken down in the mouth and mixed with saliva, so starch is changed to maltose.
O O The food is squeezed along the oesophagus by a process called peristalsis, with continued action by saliva.
O O In the stomach, food is churned into chyme and fats melt. Proteins are converted to peptides by gastric juices. Bacteria are killed by hydrochloric acid.
OO The food then moves into the small intestine, where bile splits the fat into fatty acids and glycerol. Pancreatic juices change peptides to amino acids, and starch into sugars, while working with bile to break down fats. Intestinal juices complete the digestion of macronutrients, which are absorbed through the villi.
O O In the large intestine, the remaining nutrients are absorbed. Water is absorbed. Waste is then excreted (faeces). Vitamins B and K are manufactured.
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Strand 1: Food, Health and Culinary Skills Section 2: Nutrition Know-How
