- The digestive system breaks down food into smaller molecules that can be absorbed and used to fuel body activities. It consists of a tubular gastrointestinal tract and accessory organs like the liver and pancreas. - The mouth, esophagus, and stomach are involved in initial digestion through chewing, swallowing, and stomach acid. The small intestine further breaks down food with enzymes from the pancreas and liver and absorbs nutrients. The large intestine absorbs water before waste is excreted.

1. Fueling Body Activities: Digestion Digestive System

4. Fig. 43.02(TE Art) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Gastrovascular cavity Body stalk Tentacle Mouth Food Wastes

5. Fig. 43.03(TE Art) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nematode Earthworm Salamander Mouth Mouth Mouth Pharynx Pharynx Esophagus Intestine Intestine Intestine Anus Anus Anus Crop Gizzard Liver Pancreas Stomach Cloaca

8. Human Digestive System

11. Gastrointestinal Tract Layers

13. Generalized Vertebrate Dentition

14. Fig. 43.08(TE Art) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cusp Enamel Gingiva Dentin Pulp cavity with nerves and vessels Periodontal ligaments Root canal Cementum Bone

17. Human Pharynx, Palate, and Larynx

20. Stomach and Duodenum

23. Small Intestine

31. Actions of Insulin and Glucagon

35. Table 43.01

37. Fig. 43.p906(TE Art) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Salivary gland Salivary gland b a c d Cecum Anus i g f e h j

38. Fig. 43.04(TE Art) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Salivary gland Salivary gland b. Liver a. Esophagus c. Gallbladder d. Pharynx Cecum j. Appendix Anus i. Rectum g. Small intestine f. Pancreas e. Stomach h. Colon