Chapter 41

1. Chapter 41 Animal Nutrition

2. Type Producer Also Called Autotroph Description • gets energy from nonliving resources (like the sun) • gets energy from self. self energy

3. Type Consumer Also Called Heterotroph Description • gets energy by eating other organisms • gets energy from a different source. different energy

4. Overview: The Need to Feed • Every meal reminds us that we are heterotrophs, dependent on a regular supply of food • In general, animals fall into these categories: • Herbivores eat mainly autotrophs (plants and algae) • Carnivores eat other animals • Omnivores regularly consume animals as well as plants or algal matter • Detritivores eat dead organic material (... FBI)

6. An adequate diet must satisfy three needs: • Fuel for all cellular work • Organic raw materials for biosynthesis • Essential nutrients, substances that the animal cannot make for itself • Main feeding mechanisms: suspension (filter) feeding, substrate feeding, fluid feeding, bulk feeding

7. LE 41-2a Baleen

8. LE 41-2b Caterpillar Feces

11. Concept 41.2: An animal’s diet must supply carbon skeletons and essential nutrients • An animal must obtain carbon skeletons from its food to build complex molecules • Besides fuel and carbon skeletons, a diet must supply essential nutrients in preassembled form • A malnourished animal is missing one or more essential nutrients in its diet

12. Herbivores may suffer mineral deficiencies if they graze on plants in soil lacking key minerals

13. Malnutrition is much more common than undernutrition in human populations

14. 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

16. Most plant proteins are incomplete in amino acid makeup • Individuals who eat only plant proteins need to eat a variety to get all essential amino acids

17. LE 41-10 Essential amino acids for adults Beans and other legumes Methionine Valine Threonine Phenylalanine Leucine Corn (maize) and other grains Isoleucine Tryptophan Lysine

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

20. Essential Fatty Acids • Animals can synthesize most of the fatty acids they need • The essential fatty acids are certain unsaturated fatty acids • Deficiencies in fatty acids are rare

21. 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 • water-soluble

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

27. Concept 41.3: The main stages of food processing are ingestion, digestion, absorption, and elimination • Ingestion is the act of eating • Digestion is the process of breaking food down into molecules small enough to absorb • Absorption is uptake of nutrients by body cells • Elimination is the passage of undigested material out of the digestive compartment

28. LE 41-12 Small molecules Pieces of food Chemical digestion (enzymatic hydrolysis) Nutrient molecules enter body cells Mechanical digestion Undigested material Food INGESTION ELIMINATION DIGESTION ABSORPTION

29. Digestive Compartments • Most animals process food in specialized compartments • These compartments reduce risk of self-digestion

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

31. 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 • Mouth • stomach

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

33. LE 41-13 Mouth Tentacles Gastrovascular cavity Food Epidermis Mesoglea Gastrodermis Nutritive muscular cells Flagella Gland cells Food vacuoles Mesoglea

35. 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

38. LE 41-14a Crop Gizzard Intestine Esophagus Pharynx Anus Mouth Typhlosole Lumen of intestine Earthworm

39. LE 41-14b Midgut Hindgut Foregut Esophagus Rectum Anus Crop Mouth Gastric ceca Grasshopper

40. LE 41-14c Esophagus Stomach Gizzard Intestine Mouth Crop Anus Bird

41. Concept 41.4: Each organ of the mammalian digestive system has specialized food-processing functions • 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 • Food is pushed along by peristalsis, rhythmic contractions of muscles in the wall of the canal

43. LE 41-15a Cardiac orifice Tongue Oral cavity Parotid gland Salivary glands Sublingual gland Pharynx Esophagus Submandibular gland Pyloric sphincter Liver Stomach Ascending portion of large intestine Gall- bladder Pancreas Duodenum of small intestine Ileum of small intestine Small intestine Large intestine Rectum Anus Appendix Cecum

44. LE 41-15b Salivary glands Mouth Esophagus Gall- bladder Stomach Small intestines Liver Pancreas Large intestines Rectum Anus A schematic diagram of the human digestive system

45. The Oral Cavity, Pharynx, and Esophagus • In the oral cavity, food is lubricated and digestion begins • Teeth chew food into smaller particles that are exposed to salivary amylase, initiating breakdown of glucose polymers

46. The region we call our throat is the pharynx, a junction that opens to both the esophagus and the windpipe (trachea) • The esophagus pushes food from the pharynx down to the stomach by peristalsis

47. LE 41-16_3 Bolus of food Tongue Epiglottis up Epiglottis up Pharynx Glottis down and open Esophageal sphincter contracted Glottis Esophageal sphincter relaxed Epiglottis down Esophageal sphincter contracted Larynx Glottis up and closed Trachea Esophagus Relaxed muscles To stomach To lungs Contracted muscles Relaxed muscles Stomach

48. The Stomach • The stomachstores food and secretes gastric juice, which converts a meal to acid chyme • Gastric juice is made up of hydrochloric acid and the enzyme pepsin • Pepsin is secreted as inactive pepsinogen; pepsin is activated when mixed with hydrochloric acid in the stomach • Digestion of proteins • Mucus protects the stomach lining from gastric juice

49. LE 41-17 Esophagus Cardiac orifice Stomach Pyloric sphincter 5 µm Small intestine Folds of epithelial tissue Interior surface of stomach Epithelium Pepsinogen and HCl are secreted into the lumen of the stomach. Pepsinogen Pepsin (active enzyme) Gastric gland HCl HCl converts pepsinogen to pepsin. Pepsin then activates more pepsinogen, starting a chain reaction. Pepsin begins the chemical digestion of proteins. Mucus cells Chief cells Parietal cells Chief cell Parietal cell

50. Gastric ulcers, lesions in the lining, are caused mainly by the bacterium Helicobacter pylori