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Chapter 41

Chapter 41. Animal Nutrition. Overview: The Need to Feed. Herbivores eat mainly autotrophs (plants and algae) Carnivores eat other animals Omnivores regularly consume animals as well as plants or algal matter. Essential Nutrients. There are four classes of essential nutrients:

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Chapter 41

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  1. Chapter 41 Animal Nutrition

  2. Overview: The Need to Feed • Herbivores eat mainly autotrophs (plants and algae) • Carnivores eat other animals • Omnivores regularly consume animals as well as plants or algal matter

  3. Essential Nutrients • There are four classes of essential nutrients: • Essential amino acids • Essential fatty acids • Vitamins • Minerals

  4. Essential Amino Acids • Animals require 20 amino acids and can synthesize about half • Essential amino acids- must be obtained from food in preassembled form • “Complete” proteins- provides all the essential amino acids (meat, eggs, and cheese) • Most plant proteins are incomplete in amino acid makeup

  5. Essential amino acids for adults Beans and otherlegumes Methionine Valine Threonine Phenylalanine Leucine Corn (maize)and other grains Isoleucine Tryptophan Lysine

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

  7. Vitamins • Vitamins are organic molecules required in the diet in small amounts • 13 essential vitamins • Two categories: fat-soluble and water-soluble

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

  9. Dietary Deficiencies • Undernourishment- diet with less chemical energy than the body requires • Malnourishment- absence from the diet of one or more essential nutrients

  10. Undernourishment • 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

  11. Malnourishment • Malnourishment can cause deformities, disease, and death

  12. The main stages of food processing are ingestion, digestion, absorption, and elimination • Ingestion is the act of eating

  13. Suspension Feeders • Many aquatic animals are suspension feeders, which sift small food particles from the water

  14. Leaf miner caterpillar,a substrate feeder Substrate Feeders Substrate feeders are animals that live in or on their food source Caterpillar Feces

  15. Fluid Feeders • Fluid feeders suck nutrient-rich fluid from a living host Mosquito, a fluid feeder

  16. Bulk Feeders • Bulk feeders eat relatively large pieces of food Rock python, a bulk feeder

  17. Digestion is the process of breaking food down into molecules small enough to absorb • Enzymatic hydrolysis splits bonds in molecules with the addition of water • Absorption is uptake of nutrients by body cells • Elimination is the passage of undigested material out of the digestive compartment

  18. Smallmolecules Piecesof food Chemical digestion(enzymatic hydrolysis) Nutrientmoleculesenter bodycells Mechanicaldigestion Undigestedmaterial Food Ingestion Digestion Elimination Absorption 2 4 1 3

  19. Digestive Compartments • Intracellular Digestion- food is engulfed by endocytosis and digested within food vacuoles • Extracellular Digestion- food particles are broken down outside of cells

  20. Tentacles Gastrovascularcavity Food Mouth Epidermis Gastrodermis

  21. Crop Gizzard Intestine Esophagus Pharynx Gastrovascular cavity- functions in both digestion and distribution of nutrients Complete digestive tract (alimentary canal)- digestive tube with two openings, a mouth and an anus Anus Mouth Typhlosole Lumen of intestine (a) Earthworm Foregut Midgut Hindgut Esophagus Rectum Anus Crop Mouth Gastric cecae (b) Grasshopper Stomach Gizzard Intestine Mouth Esophagus Crop Anus (c) Bird

  22. Crop Gizzard Intestine Esophagus Pharynx Anus Mouth Typhlosole Lumen of intestine (a) Earthworm

  23. Midgut Foregut Hindgut Esophagus Rectum Anus Crop Mouth Gastric cecae (b) Grasshopper

  24. Stomach Gizzard Intestine Mouth Esophagus Crop Anus (c) Bird

  25. Organs of the mammalian digestive system • Peristalsis- rhythmic contractions of muscles to push along food • Sphincters regulate the movement of material between compartments

  26. Salivaryglands Mouth Esophagus Gall-bladder Stomach Smallintestine Liver Pancreas Largeintestine Rectum Anus A schematic diagram of thehuman digestive system

  27. Tongue Sphincter Oral cavity Salivary glands Pharynx Esophagus Sphincter Liver Stomach Ascendingportion oflarge intestine Gall-bladder Duodenum ofsmall intestine Pancreas Smallintestine Smallintestine Largeintestine Rectum Anus Appendix Cecum

  28. The Oral Cavity, Pharynx, and Esophagus Salivaryglands Mouth • Oral cavity- mechanical digestion takes place • Salivary glands deliver saliva to lubricate food • Amylase- initiates breakdown of glucose polymers Esophagus Gall-bladder Stomach Smallintestine Liver Pancreas Largeintestine Rectum Anus A schematic diagram of thehuman digestive system

  29. The Oral Cavity, Pharynx, and Esophagus Salivaryglands Mouth • The tongue shapes food into a bolus and provides help with swallowing • Pharynx (throat)- opens to both the esophagus and the trachea (windpipe) Esophagus Gall-bladder Stomach Smallintestine Liver Pancreas Largeintestine Rectum Anus A schematic diagram of thehuman digestive system

  30. The Oral Cavity, Pharynx, and Esophagus Salivaryglands Mouth • Esophagus conducts food from the pharynx down to the stomach by peristalsis • Swallowing causes the epiglottis to block entry to the trachea Esophagus Gall-bladder Stomach Smallintestine Liver Pancreas Largeintestine Rectum Anus A schematic diagram of thehuman digestive system

  31. Food Epiglottisup Tongue Epiglottisup Pharynx Esophagealsphinctercontracted Epiglottisdown Glottis Glottisdownand open Esophagealsphinctercontracted Larynx Trachea Esophagus Esophagealsphincterrelaxed Glottis upand closed Relaxedmuscles Tolungs Tostomach Contractedmuscles Relaxedmuscles Sphincterrelaxed Stomach

  32. Digestion in the Stomach- Chemical Digestion in the Stomach • Gastric juice is made up of hydrochloric acid and the enzyme pepsin • Parietal cells secrete hydrogen and chloride ions separately • Chief cells secrete inactive pepsinogen,it is activated to pepsin when mixed with HCl • Mucus protects the stomach lining from gastric juice

  33. Esophagus Sphincter Stomach Sphincter 5 µm Small intestine Folds ofepithelialtissue Interior surfaceof stomach

  34. Interior surfaceof stomach Epithelium 3 1 Pepsinogen and HClare secreted. Pepsinogen Pepsin 2 HCl Gastric gland 2 HCl convertspepsinogen to pepsin. 1 3 Pepsin activatesmore pepsinogen. Mucus cells H+ Cl– Chief cells Chief cell Parietal cells Parietal cell

  35. 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 Esophagus Sphincter Stomach Sphincter 5 µm Small intestine Folds ofepithelialtissue Interior surfaceof stomach

  36. Carbohydrate digestion Protein digestion Nucleic acid digestion Fat digestion Oral cavity,pharynx,esophagus Disaccharides Polysaccharides (starch, glycogen) (sucrose, lactose) Salivary amylase Smaller polysaccharides,maltose Stomach Proteins Pepsin Small polypeptides Lumen ofsmall intes-tine DNA, RNA Fat globules Polypeptides Polysaccharides Pancreatic amylases Pancreatic trypsin andchymotrypsin Pancreatic nucleases Bile salts Maltose and otherdisaccharides Fat droplets Nucleotides Smallerpolypeptides Pancreatic lipase Pancreatic carboxypeptidase Glycerol, fattyacids, monoglycerides Amino acids Epitheliumof smallintestine(brushborder) Small peptides Nucleotidases Nucleosides Disaccharidases Dipeptidases, carboxypeptidase,and aminopeptidase Nucleosidasesandphosphatases Nitrogenous bases,sugars, phosphates Monosaccharides Amino acids

  37. Digestion in the Small Intestine Salivaryglands Mouth • Major organ of digestion and absorption • Duodenum (first part of small intestine)- acid chyme from the stomach mixes with digestive juices from the pancreas, liver, gallbladder, and the small intestine itself Esophagus Gall-bladder Stomach Smallintestine Liver Pancreas Largeintestine Rectum Anus A schematic diagram of thehuman digestive system

  38. Liver Gallbladder Bile Stomach Secretinand CCK – Gastrin + CCK + Pancreas Duodenum ofsmall intestine Secretin + Key StimulationInhibition CCK + + –

  39. Pancreatic Secretions Salivaryglands Mouth • The pancreas produces proteases trypsin and chymotrypsin, protein-digesting enzymes that are activated after entering the duodenum • Its solution neutralizes the acidic chyme Esophagus Gall-bladder Stomach Smallintestine Liver Pancreas Largeintestine Rectum Anus A schematic diagram of thehuman digestive system

  40. Bile Production by the Liver Salivaryglands Mouth • Aids in digestion and absorption of fats • Bile is made in the liver and stored in the gallbladder Esophagus Gall-bladder Stomach Smallintestine Liver Pancreas Largeintestine Rectum Anus A schematic diagram of thehuman digestive system

  41. Secretions of the Small Intestine • The epithelial lining of the duodenum produces several digestive enzymes • Most digestion occurs in the duodenum; the jejunum and ileum function mainly in absorption of nutrients and water

  42. Absorption in the Small Intestine • The small intestine has a huge surface area, due to villiand microvillithat are exposed to the intestinal lumen • The enormous microvillar surface greatly increases the rate of nutrient absorption

  43. Vein carrying bloodto hepatic portal vein Muscle layers Largecircularfolds Villi Key Nutrientabsorption Intestinal wall

  44. Microvilli (brushborder) at apical(lumenal) surface Lumen Bloodcapillaries Epithelialcells Basal surface Epithelial cells Lacteal Lymphvessel Villi Key Nutrientabsorption

  45. Absorption in the Large Intestine • Colon of the large intestine is connected to the small intestine • Cecumaids in the fermentation of plant material and connects where the small and large intestines meet • Appendix- an extension off the cecum,which plays a very minor role in immunity • The colon recover waters that has entered the alimentary canal and houses E. coli strains, some of which produce vitamins

  46. Ascendingportion oflarge intestine Smallintestine Smallintestine Largeintestine Rectum Anus Appendix Cecum

  47. Dental Adaptations Incisors • The teeth of poisonous snakes are modified as fangs for injecting venom • All snakes can unhinge their jaws to swallow prey whole Molars Canines Premolars (a) Carnivore (b) Herbivore (c) Omnivore

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