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Physical and Chemical Changes in the Digestive System

Physical and Chemical Changes in the Digestive System . Digestion and Nutrients . Digestion : is the process where food is broken down by the digestive system into small nutrients to be absorbed by the body

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Physical and Chemical Changes in the Digestive System

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  1. Physical and Chemical Changes in the Digestive System

  2. Digestion and Nutrients Digestion: is the process where food is broken down by the digestive system into small nutrients to be absorbed by the body Nutrients: are very tiny molecules that are broken down from large molecules to be absorbed and used by body cells.

  3. Digestion There are two types of digestion: • Mechanical digestion: Changes the physical form of food (physical changes) • Chemical digestion: Changes the chemical composition of food into a new substance with the aid of digestive enzymes ( chemical changes)

  4. Mechanical Digestion = Physical Change It takes place inside the mouth where teeth and tongue breakdown food. (Physical Changes) • Chew • Tear • Grind • Mash • Mix • Crush

  5. Chemical Digestion = Chemical Change • The salivary glands secrete mucus and an enzyme called saliva that breaks down carbohydrates in to sugar.

  6. Esophagus • The esophagusis a muscular tube. As we swallow, we push food along the tube until the food reaches our stomach. This process of pushing down the food is called peristalsis

  7. Stomach • The stomach mixes the Food with gastric juices called pepsin to form chyme. • The chemical digestion of proteins begins in the stomach.

  8. Which type of digestion? • Chewing a saltine? • Saliva breaking the saltine down into molecules of glucose? • Your tongue breaking pieces of a hamburger apart? • Pepsin (an enzyme) in your stomach breaking the hamburger into amino acids?

  9. Small Intestines • Here where fat molecules are broken down into smaller molecules. Which is an example of chemical digestion • The remaining food is pushed down (peristalsis) to exit the digestive system. Which is an example of physical digestion.

  10. Digestion Video • http://www.youtube.com/watch?v=AEsQxzeAry8&feature=related

  11. Why Do We Eat? • The food we eat has chemical energy stored in it. • This energy is released by breaking the food down by the digestive system. • The law of conservation of energy states: Energy can’t be destroyed or created. Energy changes forms.

  12. Why Do We Eat? Body uses this released energy to: Walk, Jump, Talk, Breath by changing • Chemical energy Mechanical energy. Also to generate body heat by changing. • Chemical energy Heat energy.

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