Presentation Transcript

1. Animal Nutrition 0 33
2. 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 plants and algae Carnivores eat other animals Omnivores regularly consume animals as well as plants or algae Most animals are also opportunistic feeders Overview: The Need to Feed

3. Figure 33.1

4. Concept 33.1: 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 to power cellular processes Organic building blocks, such as organic carbon and organic nitrogen, to synthesize a variety of organic molecules Essential nutrients, which are required by cells and must be obtained from dietary sources
5. Essential Nutrients Essential nutrients must be obtained from an animal’s diet There are four classes of essential nutrients Essential amino acids Essential fatty acids Vitamins Minerals

6. Figure 33.2

   NADH coenzyme (vitamin B3) Iron cofactor Gly Ile Leu Essential amino acids Phe NADH Phe Tyr Glu Phospholipids Fatty acid desaturase -Linoleic acid Linoleic acid Prostaglandins
7. In animals, fatty acids are converted into a variety of cellular components, such as membrane phospholipids, signaling molecules, and storage fats Essential fatty acids can be synthesized by plants Deficiencies of essential fatty acids are rare Essential Fatty Acids and Amino Acids
8. 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 Meat, eggs, and cheese provide all the essential amino acids and are thus “complete” proteins
9. Most plant proteins are incomplete in amino acid composition Individuals who eat only plant proteins need to eat specific plant combinations to get all the essential amino acids
10. Vitamins Vitamins are organic molecules required in the diet in small amounts Thirteen vitamins are essential for humans Vitamins are grouped into two categories: fat-soluble and water-soluble
11. Minerals Minerals are simple inorganic nutrients, usually required in small amounts Ingesting large amounts of some minerals can upset homeostatic balance
12. Dietary Deficiencies Malnutrition results from the long-term absence from the diet of one or more essential nutrients
13. Deficiencies in Essential Nutrients Deficiencies in essential nutrients can cause deformities, disease, and death Animals may consume salt, minerals, shells, or stones to prevent mineral deficiencies

14. Figure 33.3

15. A diet with insufficient amounts of one or more amino acids is the most common type of malnutrition among humans Individuals subsisting on simple rice diets are often deficient in vitamin A To overcome this, scientists have engineered a strain of rice that synthesizes beta-carotene, which is converted to vitamin A in the body
16. Undernutrition results when a diet does not provide enough chemical energy 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 Undernutrition
17. Assessing Nutritional Needs Genetic defects that disrupt food uptake provide information about human nutrition For example, hemochromatosis causes iron buildup without excessive iron intake 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
18. Concept 33.2: The main stages of food processing are ingestion, digestion, absorption, and elimination Food processing can be divided into four distinct stages

19. Figure 33.4

    Nutrient molecules enter body cells Mechanical digestion Chemical digestion (enzymatic hydrolysis) Undigested material Ingestion Digestion Absorption Elimination 1 2 3 4
20. Ingestion is the act of eating or feeding Strategies for extracting resources from food differ widely among animals
21. Video: Shark Eating a Seal

22. Figure 33.5

    Substrate feeders Fluid feeders Filter feeders Baleen Caterpillar Feces Bulk feeders

23. Figure 33.5a

    Filter feeders Baleen

24. Figure 33.5b

    Substrate feeders Caterpillar Feces

25. Figure 33.5c

    Fluid feeders

26. Figure 33.5d

    Bulk feeders
27. Digestion is the process of breaking food down into molecules small enough to absorb Mechanical digestion, including chewing, increases the surface area of food Chemical digestion splits food into small molecules that can pass through membranes In chemical digestion, the process of enzymatic hydrolysis splits bonds in molecules with the addition of water
28. Absorption is uptake of nutrients by body cells Elimination is the passage of undigested material out of the digestive system
29. Digestive Compartments Most animals process food in specialized compartments These compartments reduce the risk of an animal digesting its own cells and tissues
30. Intracellular Digestion In intracellular digestion, food particles are engulfed by phagocytosis Food vacuoles, containing food, fuse with lysosomes containing hydrolytic enzymes
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 Animals with simple body plans have a gastrovascular cavity that functions in both digestion and distribution of nutrients
32. Video: Hydra Eating

33. Figure 33.6

    Mouth Tentacles Food 1 Digestive enzymes released 2 Food particles broken down 3 Food particles engulfed and digested Epidermis Gastrodermis
34. More complex animals have a complete digestive tractor an alimentary canal with a mouth and an anus The alimentary canal can have specialized regions that carry out digestion and absorption in a stepwise fashion

35. Figure 33.7

    Crop Esophagus Gizzard Intestine Pharynx Anus Mouth (a) Earthworm Esophagus Midgut Hindgut Foregut Crop Esophagus Stomach Rectum Gizzard Anus Intestine Mouth Anus Crop Gastric cecae Mouth (b) Grasshopper (c) Bird
36. Concept 33.3: 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

37. Figure 33.8

    Tongue Oral cavity Salivary glands Mouth Pharynx Salivary glands Esophagus Esophagus Stomach Liver Gallbladder Sphincter Small intestine Gall- bladder Liver Sphincter Pancreas Large intestine Pancreas Stomach Small intestine Rectum Anus Large intestine Duodenum of small intestine Rectum Anus

38. Figure 33.8a

    Mouth Salivary glands Esophagus Stomach Gallbladder Small intestine Liver Pancreas Large intestine Rectum Anus
39. 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
40. The Oral Cavity, Pharynx, and Esophagus The first stage of digestion is mechanical and takes place in the oral cavity Salivary glands deliver saliva to the oral cavity through ducts Teeth chew food into smaller particles that are exposed to salivary amylase, initiating breakdown of glucose polymers Saliva also contains mucus, a viscous mixture of water, salts, cells, and glycoproteins
41. The tongue shapes food into a bolus and provides help with swallowing The throat, or pharynx, is the junction that opens to both the esophagus and the trachea The esophagus connects to the stomach The trachea (windpipe) leads to the lungs
42. Swallowing must be carefully choreographed to avoid choking The esophagusconducts food from the pharynx down to the stomach through rhythmic cycles of contraction The form of the esophagus fits its function and varies among species
43. Digestion in the Stomach The stomach stores food and secretes gastric juice, which converts a meal to a mixture of food and digestive juice called chyme

44. Figure 33.9

    Esophagus Sphincter Stomach Sphincter Small intestine 10 m Folds of epithelial tissue Gastric pit on the interior surface of stomach Epithelium 3 Production of gastric juice Pepsinogen Pepsin (active enzyme) 2 1 Pepsinogen and HCI secreted into lumen Gastric gland HCI Chief cell 1 HCI converts pepsinogen to pepsin. 2 H Mucous cell Cl− 3 Pepsin activates more pepsinogen, starting a chain reaction. Parietal cell Chief cell Parietal cell

45. Figure 33.9a

    Gastric pit on the interior surface of stomach Epithelium 3 Pepsinogen Pepsin (active enzyme) 2 Gastric gland HCI Chief cell 1 H Mucous cell Cl− Parietal cell Chief cell Parietal cell

46. Figure 33.9b-1

    Production of gastric juice Pepsinogen Pepsinogen and HCI secreted into lumen 1 HCI Chief cell 1 H Cl− Parietal cell

47. Figure 33.9b-2

    Production of gastric juice Pepsin (active enzyme) Pepsinogen 2 Pepsinogen and HCI secreted into lumen 1 HCI Chief cell 1 HCI converts pepsinogen to pepsin. 2 H Cl− Parietal cell

48. Figure 33.9b-3

    3 Production of gastric juice Pepsin (active enzyme) Pepsinogen 2 Pepsinogen and HCI secreted into lumen 1 HCI Chief cell 1 HCI converts pepsinogen to pepsin. 2 H Cl− Pepsin activates more pepsinogen, starting a chain reaction. 3 Parietal cell

49. Figure 33.9c

    10 m Gastric pit on the interior surface of stomach
50. Chemical Digestion in the Stomach Gastric juice has a low pH of about 2, which kills bacteria and denatures proteins Gastric juice is made up of hydrochloric acid (HCl) and pepsin Pepsin is a protease, or protein-digesting enzyme, that cleaves proteins into smaller peptides

51. Figure 33.10

    Carbohydrate digestion Oral cavity, pharynx, esophagus Polysaccharides Disaccharides (starch, glycogen) (sucrose, lactose) Salivary amylase Smaller polysaccharides Maltose Protein digestion Stomach Proteins Pepsin Nucleic acid digestion Small polypeptides Fat digestion Small intestine (enzymes from pancreas) DNA, RNA Fat (triglycerides) Pancreatic amylases Pancreatic trypsin and chymotrypsin Pancreatic nucleases Disaccharides Nucleotides Smaller polypeptides Pancreatic lipase Pancreatic carboxypeptidase Glycerol, fatty acids, monoglycerides Small peptides Small intestine (enzymes from epithelium) Nucleotidases Dipeptidases, carboxypeptidase, and aminopeptidase Nucleosides Disaccharidases Nucleosidases and phosphatases Nitrogenous bases, sugars, phosphates Monosaccharides Amino acids

52. Figure 33.10a

    Oral cavity, pharynx, esophagus Carbohydrate digestion Polysaccharides Disaccharides Salivary amylase Smaller polysaccharides Maltose

53. Figure 33.10b

    Stomach Protein digestion Carbohydrate digestion Smaller polysaccharides Disaccharides Maltose Proteins Pepsin Small polypeptides

54. Figure 33.10c

    Small intestine (enzymes from pancreas) Fat digestion Nucleic acid digestion Protein digestion Carbohydrate digestion Polysaccharides Disaccha- rides Small polypeptides Fat (triglycerides) DNA, RNA Pancreatic lipase Pancreatic nucleases Pancreatic amylases Pancreatic trypsin and chymotrypsin Disaccharides Nucleotides Smaller polypeptides Pancreatic carboxypeptidase Glycerol, fatty acids, monoglycerides Small peptides Amino acids

55. Figure 33.10d

    Small intestine (enzymes from epithelium) Protein digestion Carbohydrate digestion Nucleic acid digestion Nucleotides Small peptides Amino acids Disaccharides Disaccharidases Nucleotidases Dipeptidases, carboxypeptidase, and aminopeptidase Nucleosides Nucleosidases and phosphatases Nitrogenous bases, sugars, phosphates Monosaccharides Amino acids
56. Mucus protects the stomach lining from gastric juice Also, cell division adds a new epithelial layer every three days, to replace any cells damaged by digestive juices Gastric ulcers, lesions in the stomach lining, are caused mainly by the bacterium Helicobacter pylori
57. Stomach Dynamics Coordinated contraction and relaxation of stomach muscle churn the stomach’s contents Sphincters prevent chyme from entering the esophagus and regulate its entry into the small intestine Stomach contents typically pass into the small intestine 2–6 hours after a meal
58. Digestion in the Small Intestine The small intestine is the longest section of the alimentary canal It is the major organ of digestion and absorption The first portion of the small intestine is the duodenum Here, chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the intestinal wall
59. Pancreatic Secretions The pancreas produces proteases trypsin and chymotrypsin, which are activated in the lumen of the duodenum Its solution is alkaline and neutralizes the acidic chyme
60. Bile Production by the Liver In the small intestine, bile aids in digestion and absorption of fats Bile is made in the liver and stored in the gallbladder Bile also destroys nonfunctional red blood cells
61. Secretions of the Small Intestine The epithelial lining of the duodenum produces several digestive enzymes Enzymatic digestion is completed as peristalsis moves the chyme and digestive juices along the small intestine Most digestion occurs in the duodenum; the jejunum and ileum function mainly in absorption of nutrients and water

62. Figure 33.11

    Villi Microvilli (brush border) at apical (lumenal) surface Vein carrying blood to liver Lumen Epithelial cells Blood capillaries (toward capillary) Epithelial cells Muscle layers Villi Large circular folds Capillary Basal surface Intestinal wall Lacteal Lymph vessel Nutrient absorption

63. Figure 33.11a

    Vein carrying blood to liver Muscle layers Villi Large circular folds Intestinal wall Nutrient absorption

64. Figure 33.11b

    Microvilli (brush border) at apical (lumenal) surface Villi Lumen Epithelial cells Blood capillaries (toward capillary) Epithelial cells Capillary Basal surface Lacteal Nutrient absorption Lymph vessel
65. Absorption in the Small Intestine The small intestine has a huge surface area, due to villi and microvilli that project into the intestinal lumen The enormous microvillar surface creates a brush border that greatly increases the rate of nutrient absorption Transport across the epithelial cells can be passive or active depending on the nutrient
66. Video: Membrane Transport

67. Figure 33.12

    LUMEN OF SMALLINTESTINE Triglycerides Triglycerides are broken down to fatty acids and monoglycerides by lipase. 1 Epithelial cell Mono- glycerides Fatty acids Monoglycerides and fatty acids diffuse into epithelial cells and are re-formed into triglycerides. 2 Triglycerides Phospholipids, cholesterol, and proteins Triglycerides are incorporated into chylomicrons. 3 Chylomicron Chylomicrons enter lacteals and are carried away by lymph. 4 Lacteal

68. Figure 33.12a

    Triglycerides LUMEN OF SMALLINTESTINE Triglycerides are broken down to fatty acids and monoglycerides by lipase. 1 Epithelial cell Mono- glycerides Fatty acids Monoglycerides and fatty acids diffuse into epithelial cells and are re-formed into triglycerides. 2 Triglycerides

69. Figure 33.12b

    Triglycerides Phospholipids, cholesterol, and proteins Triglycerides are incorporated into chylomicrons. 3 Chylomicron Chylomicrons enter lacteals and are carried away by lymph. 4 Lacteal
70. The hepatic portal vein carries nutrient-rich blood from the capillaries of the villi to the liver, then to the heart The liver regulates nutrient distribution, interconverts many organic molecules, and detoxifies many organic molecules
71. Epithelial cells absorb fatty acids and monoglycerides and recombine them into triglycerides These fats are coated with phospholipids, cholesterol, and proteins to form water-soluble chylomicrons Chylomicrons are transported into a lacteal, a lymphatic vessel in each villus Lymphatic vessels deliver chylomicron-containing lymph to large veins that return blood to the heart
72. Absorption in the Large Intestine The colon of the large intestine is connected to the small intestine The cecum aids in the fermentation of plant material and connects where the small and large intestines meet The human cecum has an extension called the appendix,which plays a very minor role in immunity

73. Figure 33.13

    Ascending portion of colon Small intestine Appendix Cecum Junction of the small and large intestines
74. A major function of the colon is to recover water that has entered the alimentary canal The colon houses bacteria (e.g., Escherichia coli) that live on unabsorbed organic material; some produce vitamins Feces, including undigested material and bacteria, become more solid as they move through the colon
75. Feces are stored in the rectum until they can be eliminated through the anus Two sphincters between the rectum and anus control bowel movements
76. Concept 33.4: Evolutionary adaptations of vertebrate digestive systems correlate with diet Digestive systems of vertebrates are variations on a common plan However, there are intriguing adaptations, often related to diet
77. Dental Adaptations Dentition, an animal’s assortment of teeth, is one example of structural variation reflecting diet The success of mammals is due in part to their dentition, which is specialized for different diets Nonmammalian vertebrates have less specialized teeth, though exceptions exist For example, the teeth of poisonous snakes are modified as fangs for injecting venom

78. Figure 33.14

    Carnivore Herbivore Omnivore Incisors Canines Premolars Molars
79. Mutualistic Adaptations Many herbivores have fermentation chambers in their alimentary canals, where mutualistic microorganisms digest cellulose Rabbits and some rodents harbor mutualistic bacteria in their large intestines and ceca The most elaborate adaptations for an herbivorous diet have evolved in the animals called ruminants, including deer, sheep, and cattle

80. Figure 33.15

    Rumen Reticulum Esophagus Intestine Omasum Abomasum
81. Stomach and Intestinal Adaptations Many carnivores have large, expandable stomachs Herbivores and omnivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation

82. Figure 33.16

    Small intestine Small intestine Stomach Cecum Colon (large Intestine) Carnivore Herbivore

83. Figure 33.16a

84. Figure 33.16b

85. Concept 33.5: Feedback circuits regulate digestion, energy allocation, and appetite An animal’s intake of food and use of nutrients are matched to circumstance and need
86. Regulation of Digestion Each step in the digestive system is activated as needed The enteric division of the nervous system helps to regulate the digestive process The endocrine system also regulates digestion through the release and transport of hormones

87. Figure 33.17

    1 Liver Food Gallbladder Stomach Gastrin Gastric juices Stimulation Inhibition Pancreas Duodenum of small intestine 2 3 Bile Secretin and CCK Chyme Gastric juices CCK HCO3−, enzymes Secretin CCK

88. Figure 33.17a

    1 Liver Food Gallbladder Stomach Gastrin Gastric juices Stimulation Inhibition Pancreas Duodenum of small intestine

89. Figure 33.17b

    2 Bile Chyme CCK HCO3−, enzymes Secretin Stimulation CCK Inhibition

90. Figure 33.17c

    3 Secretin and CCK Gastric juices Stimulation Inhibition
91. Energy Allocation The flow and transformation of energy in an animal—its bioenergetics—determine nutritional needs An animal’s energy use per unit of time is called its metabolic rate Metabolic rate can be determined by monitoring an animal’s rate of heat loss, the amount of O2 consumed, or the amount of CO2 produced

92. Figure 33.18-1

    Organic molecules in food External environment Animal body

93. Figure 33.18-2

    Organic molecules in food External environment Animal body Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells

94. Figure 33.18-3

    Organic molecules in food External environment Animal body Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Energy lost in nitrogenous waste Cellular respiration Carbon skeletons Heat ATP

95. Figure 33.18-4

    Organic molecules in food External environment Animal body Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Energy lost in nitrogenous waste Cellular respiration Carbon skeletons Heat ATP Bio- synthesis Cellular work Heat Heat
96. Minimum Metabolic Rate Animals must maintain a minimum metabolic rate for basic cell functions Basal metabolic rate, BMR, is the minimum metabolic rate of a nongrowing endotherm that is at rest, has an empty stomach, and is not experiencing stress The metabolic rate of a fasting, nonstressed ectotherm at a particular temperature is called standard metabolic rate, SMR
97. Endothermy is more energetically costly than ectothermy For ectotherms and endotherms, activity greatly affects metabolic rate
98. Regulation of Energy Storage When an animal takes in more energy than is needed for metabolism and activity, excess energy is stored In humans, the liver and muscle cells are used first; energy is stored as glycogen When glycogen depots are full, additional excess energy is stored as fat in adipose cells When fewer calories are taken in than expended, the body expends liver glycogen, muscle glycogen, and then fat, in that order
99. Glucose Homeostasis Insulin and glucagon together maintain glucose levels Insulin levels rise after a carbohydrate-rich meal, and glucose entering the liver through the hepatic portal vein is used to synthesize glycogen When glucose concentration is low in the hepatic portal vein, glucagon stimulates the liver to break down glycogen and release glucose into the blood Insulin and glucagon are produced in the pancreas in beta cells and alpha cells, respectively
100. Video: Homeostasis

101. Figure 33.19

     Secretion of insulin by pancreas Transport of glucose into body cells and storage of glucose as glycogen Stimulus: Blood glucose level rises after eating. Homeostasis: 70–110 mg glucose/ 100 mL blood Stimulus: Blood glucose level drops below set point. Breakdown of glycogen and release of glucose into blood Secretion of glucagon by pancreas
102. Diabetes Mellitus Diabetes mellitus is a disease caused by a deficiency of insulin or a decreased response to insulin in target tissues Cells are unable to take up glucose to meet their metabolic needs Fat becomes the main substrate for cellular respiration
103. Type 1 diabetes is an autoimmune disorder in which the immune system destroys the pancreatic beta cells Type 2 diabetes is characterized by a failure of target cells to respond normally to insulin Heredity is a factor in type 2 diabetes Excess body weight and lack of exercise increase the risk
104. Regulation of Appetite and Consumption Overnourishment causes obesity, which results from excessive intake of food energy with the excess stored as fat Obesity contributes to diabetes (type 2), cancer of the colon and breasts, heart attacks, and strokes Researchers have discovered several of the mechanisms that help regulate body weight
105. Ghrelin, a hormone secreted by the stomach wall, triggers a feeling of hunger before meals Insulin and PYY, a hormone secreted by the small intestine after eating, both suppress appetite Leptin, a hormone produced by adipose (fat) tissue, also suppresses appetite and may regulate body fat levels

106. Figure 33.UN01a

107. Figure 33.UN01b

108. Figure 33.UN02

     Hepatic portal vein Veins to heart Lymphatic system Liver Absorbed food (except lipids) Absorbed water Mouth Stomach Lipids Esophagus Small intestine Anus Secretions from gastric glands Secretions from salivary glands Secretions from liver Large intestine Rectum Secretions from pancreas