Chapter 41

1. Chapter 41 Animal Nutrition

2. Overview: The Need to Feed • Food is taken in, taken apart, and taken up in the process of animal nutrition • In general, animals fall into three categories: • Herbivores eat mainly autotrophs (plants and algae) • Carnivores eat other animals • Omnivores regularly consume animals as well as plants or algal matter

3. Fig. 41-1

4. Video: Lobster Mouth Parts Video: Shark Eating a Seal

5. Concept 41.1: An animal’s diet must supply chemical energy, organic molecules, and essential nutrients • An animal’s diet provides chemical energy, which is converted into ATP and powers processes in the body • Animals need a source of organic carbon and organic nitrogen in order to construct organic molecules • Essential nutrients are required by cells and must be obtained from dietary sources

6. Essential Nutrients • There are four classes of essential nutrients: • Essential amino acids • Essential fatty acids • Vitamins • Minerals

7. Essential Amino Acids • Animals require 20 amino acids and can synthesize about half from molecules in their diet • The remaining amino acids, the essential amino acids, must be obtained from food in preassembled form • A diet that provides insufficient essential amino acids causes malnutrition called protein deficiency

8. Meat, eggs, and cheese provide all the essential amino acids and are thus “complete” proteins • Most plant proteins are incomplete in amino acid makeup • Individuals who eat only plant proteins need to eat specific plant combinations to get all essential amino acids

9. Fig. 41-2 Essential amino acids for adults Beans and otherlegumes Methionine Valine Threonine Phenylalanine Leucine Corn (maize)and other grains Isoleucine Tryptophan Lysine

10. Some animals have adaptations that help them through periods when their bodies demand extraordinary amounts of protein

11. Fig. 41-3

12. Essential Fatty Acids • Animals can synthesize most of the fatty acids they need • The essential fatty acids are certain unsaturated fatty acids that must be obtained from the diet • Deficiencies in fatty acids are rare

13. Vitamins • Vitamins are organic molecules required in the diet in small amounts • 13 vitamins essential to humans have been identified • Vitamins are grouped into two categories: fat-soluble and water-soluble

14. Table 41-1

15. Table 41-1a

16. Table 41-1b

17. Minerals • Minerals are simple inorganic nutrients, usually required in small amounts

18. Table 41-2

19. Table 41-2a

20. Table 41-2b

21. Dietary Deficiencies • Undernourishment is the result of a diet that consistently supplies less chemical energy than the body requires • Malnourishment is the long-term absence from the diet of one or more essential nutrients

22. Undernourishment • An undernourished individual will • Use up stored fat and carbohydrates • Break down its own proteins • Lose muscle mass • Suffer protein deficiency of the brain • Die or suffer irreversible damage

23. Malnourishment • Malnourishment can cause deformities, disease, and death • Malnourishment can be corrected by changes to a diet

24. Fig. 41-4

25. Assessing Nutritional Needs • Insights into human nutrition have come from epidemiology, the study of human health and disease in populations • Neural tube defects were found to be the result of a deficiency in folic acid in pregnant mothers

26. Fig. 41-5

27. Concept 41.2: The main stages of food processing are ingestion, digestion, absorption, and elimination • Ingestion is the act of eating

28. Suspension Feeders • Many aquatic animals are suspension feeders, which sift small food particles from the water

29. Fig. 41-6a Baleen Humpback whale, a suspension feeder

30. Substrate Feeders • Substrate feeders are animals that live in or on their food source

31. Fig. 41-6b Leaf miner caterpillar,a substrate feeder Caterpillar Feces

32. Fluid Feeders • Fluid feeders suck nutrient-rich fluid from a living host

33. Fig. 41-6c Mosquito, a fluid feeder

34. Bulk Feeders • Bulk feeders eat relatively large pieces of food

35. Fig. 41-6d Rock python, a bulk feeder

36. Digestion is the process of breaking food down into molecules small enough to absorb • In chemical digestion, the process of enzymatic hydrolysis splits bonds in molecules with the addition of water • Absorption is uptake of nutrients by body cells • Elimination is the passage of undigested material out of the digestive compartment

37. Fig. 41-7 Smallmolecules Piecesof food Chemical digestion(enzymatic hydrolysis) Nutrientmoleculesenter bodycells Mechanicaldigestion Undigestedmaterial Food Ingestion Digestion Elimination Absorption 2 4 1 3

38. Digestive Compartments • Most animals process food in specialized compartments • These compartments reduce the risk of an animal digesting its own cells and tissues

39. Intracellular Digestion • In intracellular digestion, food particles are engulfed by endocytosis and digested within food vacuoles

40. Extracellular Digestion • Extracellular digestion is the breakdown of food particles outside of cells • It occurs in compartments that are continuous with the outside of the animal’s body

41. Fig. 41-8 Tentacles Gastrovascularcavity Food Mouth Epidermis Gastrodermis

42. Animals with simple body plans have a gastrovascular cavity that functions in both digestion and distribution of nutrients Video: Hydra Eating Daphnia

43. More complex animals have a digestive tube with two openings, a mouth and an anus • This digestive tube is called a complete digestive tract or an alimentary canal • It can have specialized regions that carry out digestion and absorption in a stepwise fashion

44. Fig. 41-9 Crop Gizzard Intestine Esophagus Pharynx Anus Mouth Typhlosole Lumen of intestine (a) Earthworm Foregut Midgut Hindgut Esophagus Rectum Anus Crop Mouth Gastric cecae (b) Grasshopper Stomach Gizzard Intestine Mouth Esophagus Crop Anus (c) Bird

45. Fig. 41-9a Crop Gizzard Intestine Esophagus Pharynx Anus Mouth Typhlosole Lumen of intestine (a) Earthworm

46. Fig. 41-9b Midgut Foregut Hindgut Esophagus Rectum Anus Crop Mouth Gastric cecae (b) Grasshopper

47. Fig. 41-9c Stomach Gizzard Intestine Mouth Esophagus Crop Anus (c) Bird

48. Concept 41.3: Organs specialized for sequential stages of food processing form the mammalian digestive system • The mammalian digestive system consists of an alimentary canal and accessory glands that secrete digestive juices through ducts • Mammalian accessory glands are the salivary glands, the pancreas, the liver, and the gallbladder

49. Food is pushed along by peristalsis, rhythmic contractions of muscles in the wall of the canal • Valves called sphincters regulate the movement of material between compartments

50. Fig. 41-10 Tongue Sphincter Salivaryglands Oral cavity Mouth Salivary glands Pharynx Esophagus Esophagus Sphincter Liver Stomach Gall-bladder Stomach Ascendingportion oflarge intestine Gall-bladder Duodenum ofsmall intestine Smallintestine Pancreas Liver Smallintestine Smallintestine Pancreas Largeintestine Largeintestine Rectum Rectum Anus Anus Appendix A schematic diagram of thehuman digestive system Cecum