1. Digestive System Digestion- breaking down of food into smaller pieces to make usable energy for the body.

2. Two Types of Digestion Mechanical Digestion- physically breaks food down into smaller pieces -chewing with teeth -smooth muscle pushing food Chemical Digestion- enzymes and acids chemically change food into usable energy for the body. -saliva in the mouth has enzymes that make food mushy -acid in the stomach dissolves food

3. What we get from food - Carbohydrates are complex sugars. - Enzymes in saliva break carbohydrate molecule chains into simple sugars. - Sugars give us energy! Carbohydrate chain Sugar

4. What we get from food - Proteins- complex molecules that get broken down into smaller molecules called amino acids. Protein: Amino Acid: - Amino acids are used to make DNA

5. What we get from food - Lipids- complex fat chains that get broken down into fatty acids - Fatty acids are small fat molecules that give our bodies fuel Lipids

6. Energy Changes When food molecules are broken apart during chemical digestion, chemical energy is transformed into thermal energy. - Chemical energy- energy released or absorbed during a chemical reaction. - Thermal energy- energy of movement. When molecules move fast, heat is produced.

7. Digestion Digestion starts in the mouth. - the teeth and tongue help break apart food (mechanical). -enzymes in saliva begin to break down carbohydrates into sugars (chemical).

8. Digestion - When you swallow, rhythmic muscle movements in the esophagus push food from the back of the throat to the stomach (mechanical). Esophagus

9. Digestion The stomach stores food. -food is churned by stomach muscles (mechanical). -stomach acid breaks down food into a liquid mixture (chemical). -proteins and lipids start breaking down (chemical). Stomach

10. The liquid mixture passes from the stomach to the small intestine. -Food can spend up to 4 hours here. -Enzymes from the pancreas, the liver and the gall bladder finish breaking down proteins and lipids (chemical). -Nutrients from food are absorbed through the walls of the small intestine into the blood stream. The small intestine is about 20 feet long!!! Small Intestine Digestion

11. Remaining food particles are transferred to the large intestine. -Water and chemicals like sodium are removed from the food. -Bacteria in the large intestine helps in the digestion process Large Intestine The large intestine Is about 5 feet long- as tall or taller than you!

12. Waste Management - Waste left over after water is absorbed in the large intestine is stored in the rectum and pushed out of the body through the anus. - From start to finish, digestion takes about 10 hours!!!