1. Chapter 41 Animal Nutrition

2. A nutritionally adequate animal diet satisfies three needs: Fuel (chemical energy) Organic raw materials for biosynthesis (especially carbon-based molecules) Essential nutrients (substances that the animal needs, but cannot synthesize from any precursors on its own)

3. A nutritionally inadequate animal diet fails to satisfy the three basic needs we just covered Undernourishment – insufficient calories (energy) Overnourishment – too many calories & too much stored fat Malnourishment – a diet missing one or more essential nutrients

4. Energy Energy in nutrients is measured in Calories (kcal = energy to raise the temperature of 1 L of water 1º C) An “average” human body uses about 1,550 Calories/day

5. Principal categories of nutrients: Lipids – found in lipid membranes, etc.; including essential fatty acids 9 Calories per gram (a principal energy source)

6. Principal categories of nutrients: Proteins – building blocks and enzymes; animals require 20 amino acids, including essential amino acids 4 Calories per gram (usually a secondary energy source, since the breakdown of proteins produces urea, a potentially toxic compound)

7. Principal categories of nutrients: Fig. 41.10 Proteins – building blocks and enzymes; animals require 20 amino acids, including essential amino acids

8. Principal categories of nutrients: Carbohydrates – C-based building blocks and energy 4 Calories per gram; can be a very quick energy source (e.g., glucose)

9. Principal categories of nutrients: Vitamins – essential organic molecules required in small quantities

10. Water-Soluble Vitamins – excess excreted by kidneys Table 41.1

11. Fat-Soluble Vitamins – can be stored in fat tissues Table 41.1

12. Principal categories of nutrients: Minerals – essential elements and inorganic molecules (similar to mineral macro- and micro-nutrients required by plants, but also including selenium, iodine, etc.)

13. Minerals Table 41.2

14. http://www.mypyramid.gov The food guide pyramid US Department of Agriculture Grains Vegetables Fruits Oils Milk Meat & Beans

15. Food processing Ingestion – food is brought into the digestive tract Digestion – mechanical and chemical breakdown (especially via enzymatic hydrolysis, i.e., splitting macromolecules into their constituent monomers) Absorption – cells uptake small molecules that can be used in biochemical reactions and biosynthesis Elimination – undigested material passes out of the body

16. Food Processing in Humans Begins in the mouth… Fig. 41.15 Salivary glands produce saliva that lubricates the bolus of food

17. Food Processing in Humans Begins in the mouth… Fig. 41.15 Saliva contains amylase, which hydrolyzes starch

18. Food Processing in Humans Begins in the mouth… Fig. 41.15 Saliva also contains some antibodies to help prevent infections

19. Food Processing in Humans Begins in the mouth… Fig. 41.15 Saliva helps dissolve acids and sugars, so that they can be detected by the taste buds

20. Food Processing in Humans Fig. 41.16 The muscular tongue manipulates the bolus and passes it to the pharynx This triggers the swallowing reflex

21. Food Processing in Humans Fig. 41.16 The larynx moves upward and tips the epiglottis over the glottis

22. Food Processing in Humans Fig. 41.16 The larynx moves upward and tips the epiglottis over the glottis

23. Pharynx Epiglottis Esophagus Trachea Food Processing in Humans

24. Pharynx Epiglottis Esophagus Trachea ?

25. Pharynx Epiglottis Esophagus Trachea Uvula

26. Fig. 41.16 The esophogeal sphincter relaxes, allowing the esophagus to open

27. Food Processing in Humans Fig. 41.16 Once the bolus has entered the esophagus, the larynx moves back down, opening the trachea

28. Food Processing in Humans Fig. 41.16 Peristalsis (rhythmic contractions) carries the bolus to the stomach

29. The stomach is in the upper abdominal cavity, just below the diaphragm Food Processing in Humans Fig. 41.15

30. The stomach secretes gastric juice and mixes it with swallowed food Food Processing in Humans Fig. 41.15 Gastric juice contains hydrochloric acid and pepsin

31. Mucus coating helps prevent digestion of the stomach itself Food Processing in Humans Fig. 41.15

32. Food and gastric juice become acid chyme Food Processing in Humans Fig. 41.15 Acid chyme is kept in the stomach by the pyloric sphincter

33. Digestion continues in the small intestine Food Processing in Humans Fig. 41.15 Small diameter, muscular tube

34. Digestion continues in the small intestine Food Processing in Humans Fig. 41.15 In the first section, digestive secretions are added from the pancreas, gallbladder, and intestine itself

35. Fig. 41.19 Pancreatic juice: Food Processing in Humans Sodium bicarbonate, which neutralizes the acid chyme

36. Fig. 41.19 Pancreatic juice: Food Processing in Humans Amylases, lipases, nucleases, proteases (hydrolytic enzymes)

37. Fig. 41.19 Bile: Food Processing in Humans Produced in the liver, stored in the gall bladder, and contains bile salts

38. A detergent that helps disperse fats into droplets, thereby aiding their digestion (since they arrive essentially intact to the first portion of the small intestine) Fig. 41.19 Bile: Food Processing in Humans

39. Most absorption of nutrients occurs in the small intestine Food Processing in Humans Fig. 41.15

40. Fig. 41.23 Most absorption of nutrients occurs in the small intestine Food Processing in Humans SEM

41. Fig. 41.23 Most absorption of nutrients occurs in the small intestine Food Processing in Humans

42. Fig. 41.23 Folds, villi, and microvilli create a very large surface area for absorption Food Processing in Humans

43. Fig. 41.23 Capillaries line the core of each villus, surrounding a lacteal (part of the lymphatic system) Food Processing in Humans

44. Fig. 41.23 Most nutrients are absorbed into capillaries that converge in the hepatic portal vessel (leads to the liver) Food Processing in Humans

45. Fig. 41.23 Fats are absorbed into the lacteals, which lead through the lymphatic system to large veins of the circ. system Food Processing in Humans

46. Chapter 1 The small intestine meets the large intestine (colon) at a T-junction Food Processing in Humans Fig. 41.15 One arm of the T is a cecum and its appendix, whereas the other arm leads upward

47. Chapter 1 Much of the remaining water is absorbed from the contents of the large intestine Food Processing in Humans Fig. 41.15

48. Chapter 1 Populations of bacteria inhabit the large intestine; some produce vitamins (e.g., B complex and K) Food Processing in Humans Fig. 41.15

49. Chapter 1 The final compartment is the rectum Food Processing in Humans Fig. 41.15

50. Chapter 1 The final compartment is the rectum Food Processing in Humans Fig. 41.15 Undigested material is eliminated along with large quantities of bacteria (dead and alive)

51. Sponges and heterotrophic protists use intracellular digestion Digestive Systems are Adapted to their Owners’ Lifestyles H 2 O out H 2 O (+ food) enters pores H 2 O (+ food) enters pores Food flows into choanocytes Food enters by endocytosis Waste is expelled by exocytosis See Fig. 33.4

52. Hydras and most other animals use extracellular digestion Digestive Systems are Adapted to their Owners’ Lifestyles See Fig. 41.13 Mouth/Anus Ingested Crustacean Gastrovascular Cavity Digestive Cells

53. Extracellular digestion in a tube (complete digestive tract or alimentary canal) is the most efficient and effective Digestive Systems are Adapted to their Owners’ Lifestyles The animal can eat frequently, even while digesting the previous meal Specialized compartments and digestive organs can contribute to the process sequentially

54. Extracellular digestion in a tube (complete digestive tract or alimentary canal) is the most efficient and effective Digestive Systems are Adapted to their Owners’ Lifestyles See Fig. 41.14 Intestine Anus Mouth Pharynx Esophagus Crop Gizzard

55. Digestive Systems are Adapted to their Owners’ Lifestyles See Fig. 41.14 Like earthworms, birds lack teeth, so their muscular gizzards help break apart hard food particles Intestine Anus / Cloaca Esophagus Crop Gizzard Stomach Rectum

56. Animal digestive systems cannot break down cellulose Digestive Systems are Adapted to their Owners’ Lifestyles Fig. 41.28 Ruminant animals (cows, sheep, etc.) have stomachs with several chambers The first two are fermentation vats with microbes that produce cellulase

57. Vertebrate dentition generally matches the diet Digestive Systems are Adapted to their Owners’ Lifestyles Fig. 41.26 An adult human has 32 teeth: Incisors for cutting Canines for tearing Premolars and molars for grinding

58. Vertebrate intestines generally match the diet Digestive Systems are Adapted to their Owners’ Lifestyles Fig. 41.27

59. Digestive enzymes generally match the diet Digestive Systems are Adapted to their Owners’ Lifestyles E.g., most adult mammals do not produce lactase