nutrition (in humans)

• The alimentary canal is a long tube extending from the mouth to the anus (about 9m long). It consists of mouth, oesophagus, stomach, small intestine, large intestine, anus.
• Salivary amylase is an enzyme which breaks down starch (complex molecule) to give sugar.
• The lining of the canal has muscles that contract rhythmically to push the food forward. These peristaltic movements occur along the gut.
• Gastric glands present in the walls of the stomach release hydrochloric acid, pepsin, and mucus.
• Hydrochloric acid is responsible for digestion of food, destruction of molecules, and activation of pepsin.
• Pepsin is a protein-digesting enzyme.
• The mucus protects the inner lining of the stomach from the action of acid under normal conditions.
• Herbivores need a longer small intestine to digest cellulose.
• The small intestine is the site of the complete digestion of carbohydrates, fats, and proteins.