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Processing Food and Nutrition

Processing Food and Nutrition. Chapter 46. Learning Objective 1. Describe food processing, including ingestion , digestion , absorption , and egestion or elimination Compare the digestive system of a cnidarian (such as Hydra ) with that of an earthworm or vertebrate. Nutrition.

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Processing Food and Nutrition

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  1. Processing Food and Nutrition Chapter 46

  2. Learning Objective 1 • Describe food processing, including ingestion, digestion, absorption, and egestion or elimination • Compare the digestive system of a cnidarian (such as Hydra) with that of an earthworm or vertebrate

  3. Nutrition • The process of taking in and using food

  4. Food Processing • Feeding • selection, acquisition, and ingestion of food • Digestion • breaking down food mechanically, chemically • Absorption • nutrients pass from digestive tract into blood • Egestion(elimination) • undigested, unabsorbed food discharged

  5. Cnidarians and Flatworms • Food digested in gastrovascular cavity • only one opening • serves as both mouth and anus

  6. Gastrovascular Cavities

  7. Wastes Food Tentacle Mouth Food Enzymes secreted by inner layer Gastro- vascular cavity Food absorbed (b) Exhalation. Gastrodermis (a) Hydra Fig. 46-2a, p. 992

  8. (b) Flatworm Gastrovascular cavity Epidermis Food particles Pharynx Mouth Food absorbed Enzymes Wastes Lining of the intestine Food Fig. 46-2b, p. 992

  9. Complex Invertebrates and Vertebrates • Digestive tract is complete tube • with opening at each end • As food passes through tube • digestion takes place • Parts of digestive tract are specialized • to perform specific functions

  10. Complete Digestive Tract

  11. Gizzard Crop Esophagus Intestine Pharynx Anus Mouth Wastes Food Fig. 46-3, p. 992

  12. Explore various digestive systems by clicking on the figure in ThomsonNOW.

  13. KEY CONCEPTS • Food processing includes ingestion, digestion, absorption, and elimination

  14. Adaptations for Obtaining Food

  15. KEY CONCEPTS • Many animal adaptations are associated with mode of nutrition

  16. Learning Objective 2 • Trace the pathway traveled by an ingested meal in the human digestive system • Describe the structure and function of each organ involved

  17. Human Digestive System 1 • Mouth • Mechanical, enzymatic digestion of carbohydrates • Mammalian teeth • incisors for biting • canines for tearing food • premolars,molars for crushing and grinding

  18. Teeth and Diet

  19. Incisors Canines Premolars Molars (a) Carnivore. Fig. 46-6a, p. 994

  20. Canine Incisors Premolars Molars (b) Herbivore. Fig. 46-6b, p. 994

  21. Canines Incisors Premolars Molars (c) Omnivore. Fig. 46-6c, p. 994

  22. Tooth Structure

  23. Enamel Gum Crown Pulp cavity Pulp Neck Dentin Cementum Root canal Root Spongy bone Nerve Vein (a) Human lower molar. Sagittal section showing the crown, neck, and root. Artery (b) X-ray of a healthy tooth. Fig. 46-7, p. 995

  24. Human Digestive System 2 • Three pairs of salivary glands • secrete saliva (enzyme salivary amylase digests starch) • Pharynx and esophagus • carry food to stomach

  25. Human Digestive System 3 • Peristalsis • waves of muscular contraction • pushes bolus of food along digestive tract • Stomach • mechanical digestion by vigorous churning • enzyme pepsin in gastric juice digests proteins

  26. Peristalsis

  27. Relaxed muscle layer Esophagus Circular muscles contract, constricting passageway and pushing bolus ahead Longitudinal muscles contract, shortening passageway ahead of the bolus Relaxed muscle layer Food bolus Sphincter open Sphincter closed When the sphincter (ring of muscle) at the entrance of the stomach opens, food enters the stomach. A bolus is moved through the esophagus by peristaltic contractions. Stomach Stomach Fig. 46-8, p. 995

  28. Human Digestive System 4 • Rugae • folds in stomach wall • expand as stomach fills with food • Gastric glands secrete • hydrochloric acid • pepsinogen (precursor of pepsin)

  29. Stomach Structure

  30. Visceral peritoneum Esophagus Sphincter Circular muscle layer Longitudinal muscle layer Oblique muscle layer Pyloric sphincter Rugae Duodenum Fig. 46-9a, p. 996

  31. Openings into gastric glands Gastric glands Epithelium Lymph nodule Gastric mucosa Fig. 46-9b (1), p. 996

  32. Chief cell Parietal cell Nuclei Surface epithelium Chief cells Parietal cells Gastric glands Gastric glands Fig. 46-9b (2), p. 996

  33. Human Digestive System 5 • Chyme • soup of partly digested food • leaves stomach through pylorus • enters small intestine in spurts • Duodenum • location of most enzymatic digestion • produces several digestive enzymes • receives secretions from liver and pancreas

  34. Structure of Digestive Tract

  35. VISCERAL PERITONEUM Lymph nodule Villi Blood vessels SUBMUCOSA Nerve fibers MUCOSA Inner circular fibers Outer longitudinal fibers MUSCLE LAYER Fig. 46-5, p. 993

  36. Human Digestive System 6 • Liver produces bile • which emulsifies fats • Pancreas releases enzymes • digest protein, lipid, carbohydrate, RNA, DNA • Trypsin and chymotrypsin • digest polypeptides to dipeptides

  37. Human Digestive System 7 • Pancreatic lipase • degrades fats • Pancreatic amylase • digests complex carbohydrates

  38. Liver and Pancreas

  39. Stomach Inferior vena cava Right lobe of liver Right hepatic duct Pancreas Common bile duct Hepatic portal vein Pancreatic duct Gallbladder Duodenum Fig. 46-11, p. 998

  40. Human Digestive System 8 • Large intestine • cecum, colon, rectum, anus • eliminates undigested wastes • incubates bacteria (produce vitamin K, certain B vitamins)

  41. Human Digestive System

  42. Parotid salivary gland Sublingual salivary gland Pharynx Submandibular salivary gland Esophagus Liver Stomach Duodenum Gallbladder Pancreas Transverse colon Ascending colon Jejunum Descending colon lleum Cecum Sigmoid colon Vermiform appendix Rectum Anus Fig. 46-4, p. 993

  43. Insert “Human digestive system” human_digestive_m.swf

  44. Learn more about human digestion by clicking on the figures in ThomsonNOW.

  45. KEY CONCEPTS • Various parts of the vertebrate digestive system are specialized to perform specific functions; accessory glands (liver, pancreas, and salivary glands) secrete fluids and enzymes important in digestion

  46. Learning Objective 3 • Describe the step-by-step digestion of carbohydrate, protein, and lipid

  47. Carbohydrate Digestion • Polysaccharides • digested to disaccharide maltose by salivary and pancreatic amylases • Maltase in small intestine • splits maltose into glucose (main product of carbohydrate digestion)

  48. Protein Digestion • Proteins are split • by pepsin in stomach • by proteolytic enzymes in pancreatic juice • Dipeptidases • split small peptides into amino acids

  49. Lipid Digestion • Lipids are emulsified by bile salts • then hydrolyzed by pancreatic lipase

  50. Learning Objective 4 • What structural adaptations increase the surface area of the digestive tract?

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