1. Nutrition and Digestion  An overview of animal nutrition  A tour of the human digestive system  Human nutritional requirements  Nutritional disorders

2. Figure 22.0

3. OVERVIEW OF ANIMAL NUTRITION Food provides the raw materials that animals, including people, need to –build tissue and –fuel cellular work. © 2013 Pearson Education, Inc.

4. Figure 22.UN02 O2O2 Carnivores eat animals Herbivores eat plants and/or algae Omnivores eat both

5. Figure 22.UN03 Digestion Food Ingestion Mechanical digestion Chemical digestion via enzymes Food in mouth Small molecules Undigested materials Inside body Absorption Elimination 1234

6. Figure 22.UN04 Mouth (oral cavity) Digestion Absorption Chemical Mechanical Alimentary canal Accessory organs Pharynx and esophagus Stomach Small intestine Large intestine Anus Salivary glands Liver, gallbladder, pancreas Chewing Churning Salivary amylase Acid and pepsin (in gastric juice) Other enzymes Nutrients and water Water

7. Animal Diets Herbivores mainly feed on plants or algae. Carnivores mainly eat other animals. Omnivores eat –animals and –plants or algae. © 2013 Pearson Education, Inc.

8. Figure 22.1 Herbivore (mainly eats plants or algae) Carnivore (mainly eats animals) Omnivore (regularly eats animals as well as plants or algae) ANIMAL DIETS

9. The Four Stages of Food Processing Ingestion is another word for eating. Digestion is the breakdown of food into molecules small enough for the body to absorb. Absorption is the uptake of the small nutrient molecules by cells lining the digestive tract. Elimination is the disposal of undigested materials left over from food. © 2013 Pearson Education, Inc.

10. Digestion: A Closer Look The dismantling of food molecules is necessary because food molecules are –too large to cross the membranes of animal cells and –different from molecules that make up an animal’s body. © 2013 Pearson Education, Inc.

11. Mechanical digestion –begins the process and –involves physical processes like chewing. Chemical digestion is the chemical breakdown of food by digestive enzymes. Digestion: A Closer Look © 2013 Pearson Education, Inc.

12. Figure 22.2 Cheese protein (a polymer of amino acids in a specific sequence) Amino acid monomer Amino acids Human protein Breakdown of protein by human digestive system Absorption of amino acids by cells lining the small intestine; transport via bloodstream to other cells Cells use amino acids from the cheese and other foods to produce new human proteins 123

13. Figure 22.2c

14. Chemical digestion proceeds via hydrolysis, chemical reactions that break down polymers into monomers using water in the process. Like most biological reactions, digestion also requires enzymes. Digestion: A Closer Look © 2013 Pearson Education, Inc.

15. Figure 22.3 Enzyme (pepsin) Enzyme (amylase) Enzyme (lipase) Protein Carbohydrate Fat Amino acid Fatty acid Glycerol Sugar H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H OH H H H H

16. Digestive Compartments How do animals digest their food without digesting themselves? In animals, chemical digestion is contained safely within some kind of compartment. © 2013 Pearson Education, Inc.

17. As a cell engulfs food by phagocytosis, –a food vacuole forms, –which then fuses with a lysosome filled with digestive enzymes, and –as food is digested, small food molecules pass through the vacuole membrane into the cytoplasm, which nourishes the cell. Digestive Compartments © 2013 Pearson Education, Inc.

18. Food vacuoles are the simplest of all digestive compartments. Sponges are the only animals that digest food solely within their cells. Gastrovascular cavities –are digestive compartments surrounded by cells and –have only a single opening. Digestive Compartments © 2013 Pearson Education, Inc.

19. A digestive tube, or alimentary canal, has two separate openings: –a mouth and –an anus. Digestive Compartments © 2013 Pearson Education, Inc.

20. Food moves through specialized regions of a digestive tube that –digest and –absorb nutrients in a stepwise fashion. Digestive Compartments © 2013 Pearson Education, Inc.

21. Figure 22.4 Food (water flea) Gastrovascular Cavity (compartment with single opening) MAIN TYPES OF DIGESTIVE COMPARTMENTS Interior of intestine Newly engulfed food particle Single opening Gastrovascular cavity Earthworm Intestine Mouth Hydra Anus Alimentary Canal (Digestive Tract) (tube from mouth to anus) Digested food particle

22. A TOUR OF THE HUMAN DIGESTIVE SYSTEM System Map Bozeman Digestive Bozeman Digestive The human digestive system consists of –a digestive tube, the alimentary canal (or gut), and –accessory organs that secrete digestive chemicals. © 2013 Pearson Education, Inc.

23. Figure 22.5 Oral cavity (mouth) Pharynx Esophagus Stomach Small intestine Colon of large intestine Appendix Rectum Anus Salivary glands Liver Gallbladder Pancreas Tongue ALIMENTARY CANALACCESSORY ORGANS

24. The Mouth The mouth, or oral cavity, functions in –ingestion and –the preliminary steps of digestion. Chemical digestion begins in the mouth with the secretion of saliva from salivary glands. The muscular tongue –tastes, –shapes food into a ball, and –pushes the food to the back of the mouth for swallowing. © 2013 Pearson Education, Inc.

25. Figure 22.6 Incisors Canine Premolars Molars “Wisdom” tooth Tongue Opening of a salivary gland duct Teeth

26. The pharynx –connects the mouth to the esophagus and –opens to the trachea, which leads to the lungs. During swallowing, a reflex –moves the opening of the trachea upward and –tips the epiglottis to close the trachea entrance. The Pharynx © 2013 Pearson Education, Inc.

27. Figure 22.7 Epiglottis down Air flowing into open trachea (windpipe) Esophagus closed Epiglottis up Pharynx BREATHING SWALLOWING Food flowing into open esophagus Adam’s apple Trachea closed

28. The Esophagus The esophagus –is a muscular tube, –connects the pharynx to the stomach, and –moves food down by peristalsis, alternating waves of muscular contraction and relaxation. © 2013 Pearson Education, Inc.

29. Figure 22.8 Esophageal sphincter (contracted) Contracted muscles Relaxed muscles Food ball Stomach

30. The Stomach The stomach –can store food for several hours and –churns food into a thick soup called chyme. Fluid in the stomach contains gastric juice, made of –strong acid, –digestive enzymes, –mucus, and –the enzyme pepsin, which digests proteins. © 2013 Pearson Education, Inc.

31. Figure 22.9 Stomach lining secretes gastric juice (acid, enzyme molecules, and mucus) Sphincters control the flow into and out of the stomach Accordion-like folds allow the stomach to expand. Food particle Small intestine Esophagus

32. Stomach Ailments Heartburn is caused by backflow of chyme into the esophagus. Gastric ulcers are –erosions of the stomach lining and –often caused by the bacterium Helicobacter pylori. © 2013 Pearson Education, Inc.

33. Weight Loss Surgeries The most common weight loss surgery in the United States is gastric bypass. –Staples are used to reduce the stomach to about the size of a chicken egg. –The first 18 inches of the small intestine are bypassed by attaching the downstream intestine directly to the reduced stomach pouch. As a result, –patients quickly feel full when eating and –the body’s ability to absorb food is reduced. © 2013 Pearson Education, Inc.

34. Figure 22.10 Esophagus Small stomach pouch Staples New attachment Bypassed portion of stomach Tube through which food is bypassed Small intestine

35. The Small Intestine The small intestine is –the longest part of the alimentary canal and –the major organ for chemical digestion and absorption of nutrients into the bloodstream. © 2013 Pearson Education, Inc.

36. Chemical Digestion in the Small Intestine Most chemical digestion occurs in the duodenum, the first part of the small intestine. In the duodenum, chyme from the stomach mixes with –pancreatic juice, –bile, and –a digestive juice secreted by the intestinal lining. © 2013 Pearson Education, Inc.

37. Figure 22.11 Liver Gallbladder Bile Chyme Stomach Pancreas Pancreatic juice Duodenum of small intestine Intestinal enzymes

38. The pancreas secretes juice that –neutralizes stomach acids in the duodenum and –aids in digestion. The liver secretes bile, which –is stored in the gallbladder and –helps digest fats. Chemical Digestion in the Small Intestine © 2013 Pearson Education, Inc.

39. Absorption of Nutrients In the duodenum, nutrients are –completely digested and –ready to be absorbed. Nutrients only enter the body if they are absorbed into the walls of the digestive tract. © 2013 Pearson Education, Inc.

40. Figure 22.12 Food through the alimentary canalA finger through a hole Alimentary canal Mouth Anus

41. Villi and microvilli on the surface of the small intestine increase –the surface area and –capacity for absorption. Absorption of Nutrients © 2013 Pearson Education, Inc.

42. Figure 22.13 Blood vessels Interior of intestine Interior of intestine Muscle layers Nutrient absorption Nutrient absorption Nutrient absorption Epithelial cells Blood capillaries Lymphatic vessel Epithelial cells and blood capillary Intestinal wall Microvilli Villi Blood Villi

43. The Large Intestine The large intestine is –shorter, but wider, than the small intestine and –about 1.5 meters in length. At the junction of the small and large intestine is a small, finger-like extension called the appendix. –The appendix contains white blood cells that make minor contributions to the immune system. –Appendicitis is a bacterial infection of the appendix. © 2013 Pearson Education, Inc.

44. The colon –forms the main portion of the large intestine, –absorbs water from the alimentary canal, and –produces feces, the waste product of food. –The colon is composed of the cecum(receiving chamber for food from ileum), the ascending colon, the transverse colon, the descending colon, the sigmoid colon, the rectum and anus The Large Intestine © 2013 Pearson Education, Inc.

45. The rectum –forms the last 15 cm (6 inches) of the large intestine and –stores feces until elimination. The anus –consists of two sphincters and –regulates the opening of the rectum. The Large Intestine © 2013 Pearson Education, Inc.

46. Figure 22.14 Colon of large intestine End of small intestine Small intestine Nutrient flow Sphincter Appendix Rectum Anus

47. Figure 22.14b End of small intestine Nutrient flow Sphincter Appendix

48. Figure 22.15-4 Small intestine Large intestine Stomach Mouth Anus Food Feces Digestion Mechanical digestion Chewing in mouth Churning in stomach Ingestion Food into mouth Chemical digestion Saliva in mouth Acid and pepsin in stomach Enzymes in small intestine Absorption Nutrients and water in small intestine Water in large intestine Elimination Feces formed in large intestine Elimination from anus

49. HUMAN NUTRITIONAL REQUIREMENTS Proper nutrition provides –fuel for cellular work, –materials for building molecules, and –essential nutrients for health. © 2013 Pearson Education, Inc.

50. Food as Fuel Cells use cellular respiration to –extract energy stored in food molecules and –generate molecules of ATP to do work. © 2013 Pearson Education, Inc.

51. Figure 22.16 “Fuel” (organic molecules such as glucose) Cellular respiration Mitochondrion Cell O2O2 C 6 H 12 O 6 “Exhaust” and CO 2 H2OH2O ATP (energy for cellular work)

52. Calories Calories are a measure of the energy –stored in your food and –used in daily activitiesA calorie is the amount of energy required to raise the temperature of one gram of water by 1°C. A kilocalorie (kcal) is –1,000 calories, –the unit listed on food labels, and –often called Calories with an uppercase C. © 2013 Pearson Education, Inc.

53. Metabolic Rate The rate of energy consumption by the body is the metabolic rate. A person’s metabolic rate consists of –the basal metabolic rate (BMR), the amount of energy it takes to maintain body functions, and –energy needed for activities. © 2013 Pearson Education, Inc.

54. Table 22.1

55. Food as Building Material Building blocks from the breakdown of organic molecules are used to –repair tissues and –maintain tissues. Essential nutrients –are substances needed by the body but –cannot be made in the body from other molecules. © 2013 Pearson Education, Inc.

56. Essential Amino Acids In humans, eight essential amino acids –must be obtained from the diet and –are in different proportions in different foods. All eight essential amino acids can be consumed by eating –meat, eggs, or milk or –a variety of plants, typically grains and legumes such as beans, peanuts, and peas. © 2013 Pearson Education, Inc.

57. Figure 22.17 Complete meals Bread and peanut butter Rice and beans Rice and tofu Beans and other legumes Methionine Valine Threonine Phenylalanine Leucine Isoleucine Tryptophan Lysine

58. Vitamins –are organic molecules, –are required in the diet in very small amounts, and –usually assist enzymes in catalyzing metabolic reactions. “coenzymes” Too much or too little of most vitamins can cause harm. © 2013 Pearson Education, Inc.

59. Table 22.2

60. Figure 22.UN01

61. Minerals Minerals are inorganic substances required in the diet. Too much or too little of most minerals can cause harm. Iodine is used by the thyroid gland Iron is used in hemoglobin Calcium is used to make bone © 2013 Pearson Education, Inc.

62. Essential Fatty Acids Our cells make fats and other lipids by combining fatty acids and other molecules. Essential fatty acids must be obtained in the diet. © 2013 Pearson Education, Inc.

63. Decoding Food Labels On food labels, the FDA requires –the list of ingredients and –key nutrition facts. © 2013 Pearson Education, Inc.

64. Figure 22.18

65. NUTRITIONAL DISORDERS Dietary problems can cause severe health problems. © 2013 Pearson Education, Inc.

66. Malnutrition Malnutrition refers to health problems caused by an –improper or –insufficient diet. Protein deficiency –causes the most human suffering and –is concentrated where there is a great gap between food supply and population size. © 2013 Pearson Education, Inc.

67. Figure 22.19

68. Eating Disorders Eating disorders –affect millions of Americans, –are more common in women than men, and –result in malnutrition. Anorexia nervosa is self-starvation, even when a person is underweight. Bulimia involves –binge eating, –purging through induced vomiting, –abuse of laxatives, and/or –excessive exercise. © 2013 Pearson Education, Inc.

69. Obesity –is a too-high body mass index (BMI), –is the nutritional disorder of greatest concern, –affects about one-third of all Americans, and –increases the risk of heart attack, diabetes, and other diseases. © 2013 Pearson Education, Inc.

70. Figure 22.20 Weight (pounds) Height Underweight Normal Overweight Obese Extremely obese 6’4” 6’3” 6’2” 6’1” 6’0” 5’11” 5’10” 5’9” 5’8” 5’7” 5’6” 5’5” 5’4” 5’3” 5’2” 5’1” 5’0” 4’11” 4’10” 100 110 BMI <18.5 BMI 18.5–24 BMI 25–29 BMI 30–39 BMI >39 120 130 140 150 160 170 180 190 200 210 220 230240 250 260