Chapter 47: Animal Nutrition/Digestive System

1.

Question: What is the science of nutrition? Answer: The study of the nutrients and other substances in foods and how the body handles them1.

2.

Question: What basic life processes require sources of matter and energy for all organisms? Answer: Metabolism, homeostasis, growth, and reproduction2....

3.

Question: What are the basic processes of animal nutrition? Answer: Ingestion, digestion, and absorption into body cells and fluids4....

4.

Question: What is ingestion? Answer: The feeding method used to take food into the digestive cavity6.

5.

Question: What is digestion? Answer: The splitting of carbohydrates, proteins, lipids, and nucleic acids in foods into chemical subunits small enough to be absorbed6.

6.

Question: What is absorption? Answer: The movement of organic molecules, electrolytes, vitamins, and water across the digestive epithelium and into the interstitial fluid6.

7.

Question: What are the four groups animals fall into regarding feeding methods and the physical state of organic molecules consumed? Answer: Fluid feeders, suspension feeders, deposit feeders, and bulk feeders7....

8.

Question: What do fluid feeders ingest? Answer: Liquids containing organic molecules in solution8....

9.

Question: What do suspension feeders ingest? Answer: Small organisms suspended in water8....

10.

Question: What do deposit feeders ingest? Answer: Particles of organic matter from the solid material they live in or on8....

11.

Question: What do bulk feeders consume? Answer: Sizeable food items whole or in large chunks8....

12.

Question: What are the three main feeding strategies for animals based on their primary diet? Answer: Herbivores (plant-eating), carnivores (meat-eating), and omnivores (eat both)5....

13.

Question: What is chemical energy? Answer: The energy in food12.

14.

Question: How is energy requirement described? Answer: In terms of calories12.

15.

Question: What is a calorie? Answer: The amount of energy required to raise the temperature of 1.0g of pure water by 1°C5....

16.

Question: What is a kilocalorie (kcal)? Answer: 1,000 calories or one Calorie (capital C)5....

17.

Question: How many kcal are in a gram of carbohydrates? Answer: About 4.2 kcal per gram13....

18.

Question: How many kcal are in a gram of fats? Answer: About 9.5 kcal per gram13....

19.

Question: How many kcal are in a gram of proteins? Answer: About 4.1 kcal per gram13....

20.

Question: What do we need to continually replenish from foods to maintain ourselves? Answer: Energy and nutrients14....

21.

Question: What are nutrients? Answer: Chemical substances obtained from food and used in the body to provide energy, structural materials, and regulating agents to support growth, maintenance, and repair of the body’s tissues3....

22.

Question: What are simple inorganic nutrients? Answer: Minerals that do not contain carbon, like Calcium, magnesium, zinc, iron, potassium17....

23.

Question: What are complex organic nutrients? Answer: Carbohydrates, lipids, proteins, and vitamins; they contain carbon17....

24.

Question: What is malnutrition? Answer: Deficiencies, excesses, or imbalances in a person’s intake of energy and/or nutrients18....

25.

Question: What are the three broad groups of conditions addressed by the term malnutrition? Answer: Undernutrition, micronutrient-related malnutrition, and overnutrition18....

26.

Question: What is undernutrition? Answer: Insufficient intake of energy and nutrients to meet an individual’s needs to maintain good health18....

27.

Question: What does undernutrition include? Answer: Wasting, stunting, and underweight19.

28.

Question: What does micronutrient-related malnutrition include? Answer: Micronutrient deficiencies or excess19.

29.

Question: What is overnutrition? Answer: Excessive intake of nutrients, leading to accumulation of body fat that impairs health, or adverse effects from regular intakes in excess of needs over time18....

30.

Question: What are essential nutrients? Answer: Organic molecules that animals cannot synthesize themselves and must obtain in the diet18....

31.

Question: What are the four types of essential nutrients? Answer: Essential amino acids, essential fatty acids, vitamins, and essential minerals7....

32.

Question: What are the eight essential amino acids for adult humans? Answer: Lysine, tryptophan, phenylalanine, threonine, valine, methionine, leucine, and isoleucine18....

33.

Question: Which essential amino acid is also required by infants and young children? Answer: Histidine18....

34.

Question: What are the two essential fatty acids in the human diet? Answer: Linoleic acid and linolenic acid9....

35.

Question: Why are linoleic acid and linolenic acid required? Answer: For the synthesis of phospholipids that form parts of biological membranes and certain hormones26....

36.

Question: What health risk is associated with a diet deficient in linoleic acid and linolenic acid? Answer: Serious risk for developing coronary heart disease26....

37.

Question: What are vitamins? Answer: Organic compounds that people need in small quantities18....

38.

Question: How many known vitamins do humans require in their diet? Answer: 1328....

39.

Question: What are the two classes of vitamins? Answer: Water-soluble (hydrophilic) and fat-soluble (hydrophobic)26....

40.

Question: Where does the body store fat-soluble vitamins? Answer: In adipose tissues30.

41.

Question: What happens to water-soluble vitamins consumed above daily nutritional requirements? Answer: They are excreted in the urine30.

42.

Question: Which vitamin can humans synthesize in the skin when exposed to ultraviolet light? Answer: Vitamin D29....

43.

Question: What is vitamin K required for? Answer: Making blood-clotting factors in the liver29....

44.

Question: How do humans get much of their vitamin K requirement? Answer: Bacterial activity in the large intestine29....

45.

Question: Name the four fat-soluble vitamins? Answer: Vitamin A, D, E and K.34.

46.

Question: What two essential fatty acids are essential to the human diet? Answer: Linoleic acid and Linolenic acid (note difference!)34.

47.

Question: What are minerals? Answer: Essential inorganic elements required in the human diet18....

48.

Question: What are macrominerals? Answer: Minerals required in large amounts (100 mg to more than 1 gram per day)34....

49.

Question: Name some macrominerals. Answer: Calcium, phosphorus, magnesium, sodium, potassium, chloride, and sulfur35....

50.

Question: What are trace minerals? Answer: Minerals required in small amounts (some less than 1 mg per day)34....

51.

Question: Name some trace minerals. Answer: Iron, manganese, copper, iodine, zinc, cobalt, fluoride, and selenium35....

52.

Question: What happens with overdoses of some minerals like Iron or sodium? Answer: They can cause various problems like elevated blood pressure (too much sodium) or liver, heart, pancreas and blood vessel damage (excessive iron)36....

53.

Question: What is intracellular digestion? Answer: Digestion that occurs inside body cells7....

54.

Question: In which animals does intracellular digestion occur exclusively? Answer: Sponges and some cnidarians38.

55.

Question: How do cells in sponges take in food particles for intracellular digestion? Answer: By endocytosis through pores in the body wall9....

56.

Question: What happens to the endocytic vesicle containing food particles during intracellular digestion in sponges? Answer: It fuses with a lysosome containing hydrolytic enzymes to form endolysosomes9....

57.

Question: What is extracellular digestion? Answer: Digestion that occurs outside body cells, in a pouch or tube enclosed within the body7....

58.

Question: Which animals primarily use extracellular digestion? Answer: Most invertebrates and all vertebrates39....

59.

Question: What are the advantages of extracellular digestion? Answer: It greatly expands the range of available food sources and allows animals to eat large batches of food41....

60.

Question: What is a gastrovascular cavity? Answer: A sac-like digestive system with one opening that serves as both mouth and anus40.

61.

Question: In animals with a gastrovascular cavity, where does digestion begin and end? Answer: Digestion begins in the gastrovascular cavity and is completed intracellularly39....

62.

Question: What type of digestive system do most invertebrates and all vertebrates have? Answer: A tubular digestive tract system with two openings (mouth to anus)42....

63.

Question: What is mechanical processing in digestion? Answer: Breaking food into smaller pieces, like chewing or mastication, increasing surface area for enzymes43....

64.

Question: What happens during secretion of enzymes and other digestive aids? Answer: Enzymes, acids, emulsifiers, and lubricating mucus are released into the digestive tube44....

65.

Question: What is enzymatic hydrolysis? Answer: Food molecules are broken down through enzyme-catalyzed reactions into absorbable molecular subunits44....

66.

Question: What happens during absorption? Answer: Molecular subunits are absorbed from the digestive contents into body fluids and cells44....

67.

Question: What happens during elimination? Answer: Undigested materials are expelled through the anus44....

68.

Question: Five Steps of Digestion process Answer: 1. Mechanical processing (mastication)43.... 2. Secretion of enzymes and aids44.... 3. Enzymatic hydrolysis44.... 4. Absorption44.... 5. Elimination44....

69.

Question: What are the four major layers of the mammalian digestive tract wall? Answer: Mucosa, submucosa, muscularis, and serosa9....

70.

Question: Describe the mucosa layer of the gut wall. Answer: The innermost layer facing the lumen, containing epithelial and glandular cells, connective tissue, and smooth muscle. Absorbs nutrients, secretes enzymes/mucus, seals contents49....

71.

Question: Describe the submucosa layer of the gut wall. Answer: A thick layer of elastic connective tissue containing neuron networks (enteric nervous system), blood and lymph vessels, and small glands. Provides local control, transports absorbed lipids50....

72.

Question: Describe the muscularis layer of the gut wall. Answer: Formed by two smooth muscle layers (circular and longitudinal), plus an oblique layer in the stomach. Responsible for mechanical processing and moving materials via peristalsis51....

73.

Question: Describe the serosa layer of the gut wall. Answer: The outermost layer of the GI wall, made up of serous membrane, which is the visceral layer of the peritoneum52....

74.

Question: Layers of the GI Tract process/parts of____ Answer: Mucosa (innermost, epithelial/glandular cells), Submucosa (connective tissue, nerves, vessels), Muscularis (smooth muscle layers), Serosa (outermost, serous membrane)49....

75.

Question: What are sphincters? Answer: Powerful rings of smooth muscle that form valves between major regions of the digestive tract and control passage of contents54....

76.

Question: Name some key sphincter muscles in the digestive tract. Answer: Pharyngoesophageal (Upper esophageal), Gastroesophageal (lower esophageal), Pyloric, Ileocecal, and Anal sphincter59....

77.

Question: What is GERD (Gastroesophageal Reflux Disease)? Answer: Unpleasant symptoms (heartburn, acid indigestion) caused by the backward flow of stomach acid into the esophagus60....

78.

Question: What condition can develop if GERD is left untreated? Answer: Barrett esophagus, which involves serious pathological (precancerous) changes in the esophageal lining61....

79.

Question: What happens in the mouth during digestion? Answer: Teeth cut, tear, and crush food (mastication), forming a bolus. Saliva is secreted containing salivary amylase, mucus, bicarbonate ions, and lysozyme. Sensory analysis, mechanical digestion, lubrication, and limited chemical digestion occur65....

80.

Question: What substance in saliva hydrolyzes starches? Answer: Salivary amylase46....

81.

Question: What is a bolus? Answer: A ball of chewed or liquid food formed in the mouth for swallowing65....

82.

Question: What prevents food from entering the trachea during swallowing? Answer: The epiglottis63....

83.

Question: What moves the bolus down the esophagus to the stomach? Answer: Peristalsis63....

84.

Question: Swallowing Reflex pathway/reaction Answer: 1. Tongue pushes bolus back72. 2. Soft palate blocks nasal cavity, larynx rises, epiglottis closes trachea72. 3. Pharyngeal constrictors push bolus down72. 4. Upper esophageal sphincter opens72. 5. Esophageal peristalsis moves bolus to stomach63....

85.

Question: T/F: The muscularis layer of the gut is responsible for peristalsis through the contraction and relaxation of smooth muscles Answer: T58.

86.

Question: T/F: The serosa is the innermost layer of the gastrointestinal (GI) wall Answer: F58. →(It’s the outermost)58.

87.

Question: Which of the following substances is found in saliva and helps break down starches? A. Lysozyme B. Bicarbonate C. Salivary amylase D. Pepsin Answer: C. Salivary amylase58.

88.

Question: Peristalsis process Answer: Waves of muscular contractions. Circular muscles contract behind the bolus, relax ahead. Longitudinal muscles ahead contract. Wave of circular contraction forces bolus forward69....

89.

Question: What are the four major functions of the stomach? Answer: Storage of ingested food, mechanical breakdown of food, disruption of chemical bonds by acid and enzymes, and production of intrinsic factor70....

90.

Question: What is chyme? Answer: A viscous, highly acidic, soupy mixture of partially digested food and gastric secretions in the stomach75....

91.

Question: What are rugae? Answer: Prominent folds in the stomach mucosa when the stomach is relaxed (empty)74....

92.

Question: What are the three layers of muscle in the stomach's muscularis? Answer: Outer longitudinal, middle circular, and inner oblique layer57....

93.

Question: Cells of the Stomach process/parts of____ Answer: Chief cells (secrete pepsinogen), Parietal cells (secrete HCl and intrinsic factor), Mucous cells (secrete alkaline mucus)74....

94.

Question: What do parietal cells secrete? Answer: Hydrochloric acid (HCl) and intrinsic factor74....

95.

Question: What is intrinsic factor needed for? Answer: The absorption of vitamin B12 in the small intestine70....

96.

Question: What do chief cells secrete? Answer: Pepsinogen, an inactive proenzyme74....

97.

Question: What is pepsinogen converted to, and what does it do? Answer: Converted to pepsin by HCl; begins protein digestion76....

98.

Question: What does the alkaline mucus secreted by mucous cells protect? Answer: The stomach lining from the acidic environment74....

99.

Question: Chief cells are responsible for producing…? Answer: Pepsinogen81.

100.

Question: What happens in the small intestine? Answer: Most of the important digestive and absorptive steps occur here; chemical digestion is completed and 90% of nutrient absorption takes place48....

101.

Question: What increases the absorptive surface area of the small intestine? Answer: Folded walls, villi, and microvilli (brush border)83....

102.

Question: What are the three segments of the small intestine? Answer: Duodenum, jejunum, and ileum81....

103.

Question: What happens in the duodenum? Answer: It's a "mixing bowl"; receives chyme from the stomach and digestive secretions from the pancreas and liver85....

104.

Question: What happens in the jejunum? Answer: The bulk of chemical digestion and nutrient absorption occurs here81....

105.

Question: What happens in the ileum? Answer: The final and longest segment of the small intestine85....

106.

Question: What is the role of the pancreas in digestion in the small intestine? Answer: Secretes digestive enzymes (proteases, amylase, nucleases, lipases) and bicarbonate ions to neutralize chyme83....

107.

Question: What is the role of the liver in digestion in the small intestine? Answer: Secretes bile48....

108.

Question: What is the role of bile in digestion? Answer: Contains bile salts that facilitate the digestion and absorption of lipids by emulsification86....

109.

Question: What is bilirubin? Answer: A yellow pigment in bile derived from worn-out red blood cells87....

110.

Question: Where does digestion of disaccharides and small peptides take place in the small intestine? Answer: Across the plasma membranes of brush-border epithelial cells, which produce disaccharidases and aminopeptidases93....

111.

Question: T/F: The liver primarily produces digestive enzymes that work in the small intestine. Answer: False81. (The pancreas produces most enzymes, the liver produces bile)

112.

Question: T/F: Bile is composed of bilirubin, bile salts, and cholesterol. Answer: True81.

113.

Question: What are the three parts of the small intestine? Where does the majority of chemical digestion occur? Answer: Duodenum, Jejunum, and Ileum. The jejunum81.

114.

Question: Which cell is responsible for the production of HCl and intrinsic factor? Answer: Parietal cells.81.

115.

Question: What is the role of the liver in processing absorbed nutrients? Answer: Absorbed nutrients travel to the liver via the hepatic portal vein. The liver stores excess glucose as glycogen, synthesizes lipoproteins, detoxifies substances, and inactivates hormones/drugs48....

116.

Question: Nutrients enter the liver via the ___________. Answer: hepatic portal vein.92.

117.

Question: What is the main function of the large intestine? Answer: Reabsorb water and ions, secrete mucus/bicarbonate, reabsorb vitamins, and prepare fecal material for defecation48....

118.

Question: What does the reabsorption of water in the large intestine do? Answer: Condenses and compacts the digestive contents into solid masses (feces)91....

119.

Question: What role do intestinal bacteria (gut microbiome) play in the large intestine? Answer: Metabolize sugars/nutrients, produce useful fatty acids and vitamins (K, B vitamins), convert bilirubin into urobilinogens and stercobilinogens, and produce gas1....

120.

Question: Name some vitamins produced by bacteria in the large intestine. Answer: Vitamin K, folic acid (B9), biotin (B7), pantothenic acid (B5)91....

121.

Question: Which one of these are not waste produced from the large intestine? A. Carbon dioxide B. Hydrogen sulfide C. Bilirubin D. Ammonia E. Indole Answer: C. Bilirubin92. (Bilirubin is converted by bacteria, but not itself a waste product produced by the large intestine or its bacteria in this context; it's a precursor)

122.

Question: What generates the odor of feces? Answer: Bacterial breakdown of peptides generating ammonia, indole, skatole, and hydrogen sulfide92....

123.

Question: How is the digestive process regulated? Answer: By interactions of the autonomic nervous system, local neuron networks (enteric NS) in the gut wall, and endocrine glands48....

124.

Question: Which part of the brain plays a central role in regulating food intake? Answer: The hypothalamus104....

125.

Question: What hormones are important for long-term regulation of energy balance? Answer: Leptin and insulin104....

126.

Question: What hormones are important for short-term regulation of energy balance? Answer: Ghrelin and peptide YY104....

127.

Question: What is leptin? Answer: A satiety hormone secreted by adipocytes (fat cells). It acts on the hypothalamus to suppress appetite104....

128.

Question: What does ghrelin do? Answer: Acts on the hypothalamus to stimulate appetite (hunger hormone)104....

129.

Question: What does peptide YY do? Answer: Acts on the hypothalamus to signal satiety (fullness)104....

130.

Question: What does insulin do regarding food intake regulation? Answer: Acts on the hypothalamus to suppress food intake (satiety hormone)104....

131.

Question: What does the structure and type of an animal's teeth reflect? Answer: Its diet, feeding method, and habitat110....

132.

Question: Name the teeth type that are for grinding and chewing? Answer: Premolars and Molars118.

133.

Question: True or False: Generally, the intestinal tracts of carnivores are longer than that of herbivores? Answer: F118. (Herbivores have longer tracts)

134.

Question: How does the length of the digestive tract compare in carnivores and herbivores? Answer: Carnivores have a relatively short intestine; herbivores have a long intestinal tract119....

135.

Question: Why do herbivores have longer intestinal tracts? Answer: To allow them to extract more nutrients from plant matter, which is difficult to digest120....

136.

Question: What are microbiomes? Answer: The complete collections of microorganisms associated with a particular organism, mostly bacteria123....

137.

Question: What role do gut microbiomes play in herbivores? Answer: Many microorganisms synthesize cellulase to hydrolyze plant cellulose, aiding in digestion (mutualism)125....

138.

Question: What is cellulase? Answer: The enzyme that hydrolyzes the cellulose of plant cell walls into glucose subunits125....

139.

Question: What is a ruminant? Answer: Herbivores like cattle, deer, goats, sheep, and antelopes that have a complex, four-chambered stomach121....

140.

Question: Digestion in Ruminants process/pathway Answer: Bolus goes to rumen and reticulum (microbial fermentation) -> Animal regurgitates and rechews cud -> Re-swallowed cud goes to omasum (water absorption) -> Matter moves to abomasum (gastric digestion) -> Intestine (absorption)127....

141.

Question: What are the four chambers of a ruminant stomach? Answer: Rumen, reticulum, omasum, and abomasum127.

142.

Question: What happens in the rumen and reticulum of a ruminant? Answer: Symbiotic microorganisms hydrolyze cellulose for fermentation reactions, generating nutrients and methane gas127....

143.

Question: What happens in the omasum of a ruminant? Answer: Water is absorbed127....

144.

Question: What happens in the abomasum of a ruminant? Answer: Acids and pepsin kill microorganisms and start typical vertebrate digestion (gastric stomach)