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Understanding Physical and Chemical Changes in the Digestive System

Discover the intricacies of digestion, where food is transformed into nutrients that the body absorbs. Digestion involves two main processes: mechanical digestion, which alters the food's physical form (like chewing and grinding), and chemical digestion, which changes its chemical composition through enzymes (like saliva breaking down carbohydrates). This guide explores the role of the mouth, esophagus, stomach, and small intestine in digestion. Learn how nutrients provide energy for bodily functions, adhering to the law of conservation of energy.

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Understanding 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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