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The Digestive System 1 of 9 © Boardworks Ltd 2015 Digestive functions 2 of 9 © Boardworks Ltd 2015 Breaking down substances The mechanical breakdown of food into smaller pieces is called physical digestion. This process occurs: by chewing food in the mouth by squeezing in the stomach. What is the purpose of physical digestion? Smaller pieces of food will pass more easily through the alimentary canal. Smaller pieces of food will provide a greater surface area for enzymes to break down the substance further. 3 of 9 © Boardworks Ltd 2015 From the mouth to the stomach 4 of 9 © Boardworks Ltd 2015 From the small intestine to the blood Physical digestion continues in the stomach as it squeezes its contents into the small intestine. glucose Here, the digested particles are absorbed into the blood to be taken elsewhere in the body. Only smaller molecules, such as glucose, are able to diffuse from the small intestine, through the villi, and into the blood, moving from higher to lower concentration. 5 of 9 © Boardworks Ltd 2015 Enzymes in the body Enzymes catalyze thousands of reactions that need to take place in order to maintain life. What are some of these reactions? respiration protein synthesis digestion. Digestive enzymes break down large food molecules into smaller molecules so they can be absorbed into the blood. This is called chemical digestion. 6 of 9 © Boardworks Ltd 2015 Enzymes of digestion 7 of 9 © Boardworks Ltd 2015 Further breakdown of starch 8 of 9 © Boardworks Ltd 2015 Want to see more? This is only a sample of one of thousands of Boardworks Science PowerPoints. To see more of what Boardworks can offer, why not order a full presentation, completely free? Head to: www.boardworks.co.uk/internationalsciencepresentation 9 of 9 © Boardworks Ltd 2015