Chapter 41 ~ Animal Nutrition

Nutritional Requirements Undernourishment: caloric deficiency Undernourishment: caloric deficiency Overnourishment (obesity): excessive food intake Overnourishment (obesity): excessive food intake Leptin-appetite supressing hormone Leptin-appetite supressing hormone Malnourishment: essential nutrient deficiency Malnourishment: essential nutrient deficiency

Leptin deficient rat on left

Essential nutrients: materials that must be obtained in preassembled form Essential nutrients: materials that must be obtained in preassembled form Essential amino acids: the 8 amino acids that must be obtained in the diet Essential amino acids: the 8 amino acids that must be obtained in the diet Complete & incomplete proteins, limiting amino acids. Essential fatty acids: unsaturated fatty acids; linoleic; and alpha- linolenic; Ω-3; Ω-6 Essential fatty acids: unsaturated fatty acids; linoleic; and alpha- linolenic; Ω-3; Ω-6 phospholipids in cell membranes—esp. nervous tissue

Special Adaptations Adelei penguins- Antartica Adelei penguins- Antartica Store extra protein. Store extra protein. Amino acids from catabolism used to replace feathers following molting. Amino acids from catabolism used to replace feathers following molting. (amino acids not stored)

Vitamins: Vitamins: many are organic coenzymes (B-vits) many are organic coenzymes (B-vits) a) water soluble-excreted a) water soluble-excreted b) fat soluble-stored in adipose tissue—can be toxic in excess b) fat soluble-stored in adipose tissue—can be toxic in excess A,D,E,K A,D,E,K A) Vision-Retinol; skin A) Vision-Retinol; skin D) bone development—rickets—bowed legs D) bone development—rickets—bowed legs E) antioxidant E) antioxidant K) blood clotting K) blood clotting

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Minerals: inorganic cofactors Minerals: inorganic cofactors Calcium: bones; muscle contraction; nerve impulses Calcium: bones; muscle contraction; nerve impulses Iodine: goiter; naturally occuring in marine water Iodine: goiter; naturally occuring in marine water Iron: oxygen transport (hemoglobin) Iron: oxygen transport (hemoglobin)

Food types/feeding mechanisms Opportunistic Opportunistic Herbivore: eat autotrophs Herbivore: eat autotrophs Carnivore: eat other animals Carnivore: eat other animals Omnivore: both Omnivore: both Feeding Adaptations Feeding Adaptations Suspension-feeders: sift food from water (baleen whale) Suspension-feeders: sift food from water (baleen whale) Substrate-feeders: live in or on their food (leaf miner) (earthworm: deposit-feeder) Substrate-feeders: live in or on their food (leaf miner) (earthworm: deposit-feeder) Fluid-feeders: suck fluids from a host (mosquito); hummingbirds Fluid-feeders: suck fluids from a host (mosquito); hummingbirds Bulk-feeders: eat large pieces of food (most animals) Bulk-feeders: eat large pieces of food (most animals)

Overview of food processing-4 stages 1-Ingestion: act of eating 1-Ingestion: act of eating 2-Digestion: process of food break down 2-Digestion: process of food break down enzymatic hydrolysis A) intracellular: breakdown within cells (sponges); or within membrane (paramecium) B) extracellular: breakdown outside cells (most animals) alimentary canals (digestive tract) 3- Absorption: cells take up small molecules 3- Absorption: cells take up small molecules 4- Elimination: removal of undigested material 4- Elimination: removal of undigested material

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig Extracellular digestion Hydra Hydra 2 tissue layers 2 tissue layers Inner layer Inner layer Forms digestive Cavity Incomplete digestive Incomplete digestiveSystem (only 1 opening) (only 1 opening)

Mammalian digestion I (complete- 2 openings) Peristalsis: rhythmic waves of contraction by smooth muscle Peristalsis: rhythmic waves of contraction by smooth muscle Sphincters: ring-like valves that regulate passage of material Sphincters: ring-like valves that regulate passage of material Accessory glands: salivary glands; pancreas; liver; gall bladder Accessory glands: salivary glands; pancreas; liver; gall bladder

Mammalian digestion: 1. Ingestion & initial digestion Oral cavity Oral cavity Mechanical and chemical digestion Mechanical and chemical digestion Teeth-reduce size\increase surface area Teeth-reduce size\increase surface area salivary amylase bolus salivary amylase bolus Pharynx-juncture Pharynx-juncture epiglottis-cartilage flap, closes epiglottis-cartilage flap, closes off trachea when swallowing off trachea when swallowing Esophagus—food tube Esophagus—food tube

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig Stomach Bolus passes through Cardiac Sphincter- enters stomach Bolus passes through Cardiac Sphincter- enters stomach (occasional backflow—heartburn) (occasional backflow—heartburn) Preliminary digestion, stores food Preliminary digestion, stores food Mechanical (churning) and chemical digestion Mechanical (churning) and chemical digestion gastric juice secreted: Contains HCl & pepsin gastric juice secreted: Contains HCl & pepsin pepsinogen activated to pepsin via HCl-- begins protein digestion pepsinogen activated to pepsin via HCl-- begins protein digestion Positive feedback-increasingly more pepsin activation acid chyme pyloric sphincter

Small Intestine: Digestion & Absorption: Digestion of carbohydrates, proteins, nucleic acids, fats Acid Chyme passes through Pyloric Sphincter into Small intestine (duodenum) Acid Chyme passes through Pyloric Sphincter into Small intestine (duodenum) bile : secreted into S.I. bile : secreted into S.I. Produced by liver Produced by liver Stored in Gall Bladder Stored in Gall Bladder Bile salts-emulsifiers ( no enzymes)—break up & coat fat Bile salts-emulsifiers ( no enzymes)—break up & coat fat Some proteases secreted by intestine Some proteases secreted by intestine Pancreas: secretes bicarbonate & enzymes Pancreas: secretes bicarbonate & enzymes Amylases (carbs); lipases (fats); nucleases Amylases (carbs); lipases (fats); nucleases some proteases secreted in inactive form and activated by a membrane-bound enteropeptidase some proteases secreted in inactive form and activated by a membrane-bound enteropeptidase Disaccharidases (in intestinal walls) Disaccharidases (in intestinal walls)

Activation of pancreatic peptidases within the intestine

3. Nutrient Absorption S.I. highly folded S.I. highly folded Villi (finger-like projections) & microvilli (appendages of villi) increase absorptive surface Villi (finger-like projections) & microvilli (appendages of villi) increase absorptive surface Small vessels in villi absorb: Small vessels in villi absorb: lacteals (lipids pass into) lacteals (lipids pass into) & capillaries (other nutrients) & capillaries (other nutrients)

Chylomicrons form: complex of fat, cholesterol, & protein) Chylomicrons form: complex of fat, cholesterol, & protein) Carried by lacteals; dump into veins returning to the heart Carried by lacteals; dump into veins returning to the heart Other nutrients—travel to liver via Hepatic portal vessel Other nutrients—travel to liver via Hepatic portal vessel

Large intestine (colon)- absorb water; concentrate residue Large intestine (colon)- absorb water; concentrate residue Bacterial symbionts- generate some vitamins—K, biotin Bacterial symbionts- generate some vitamins—K, biotin Cecum-small pouch Cecum-small pouch At tip is the Appendix At tip is the Appendix Feces Feces Rectum--storage Rectum--storage Anus--elimination Anus--elimination Large Intestine

Hormonal Regulation of Digestion Hormonal Regulation of Digestion Gastrin food---> stomach wall ---> gastric juice Gastrin food---> stomach wall ---> gastric juice Enterogastrones (duodenum) Enterogastrones (duodenum) 1. Secretin - 1. Secretin - acidic chyme---> secretin --> pancreas to release bicarbonate (neutralize chyme) acidic chyme---> secretin --> pancreas to release bicarbonate (neutralize chyme) 2. Cholecystokinin (CCK) 2. Cholecystokinin (CCK) amino/fatty acids---> pancreas to release enzymes and gall bladder to release bile amino/fatty acids---> pancreas to release enzymes and gall bladder to release bile

Evolutionary adaptations Dentition: an animal’s assortment of teeth Dentition: an animal’s assortment of teeth Digestive system length Digestive system length Herbivores-longer Herbivores-longer Symbiosis Symbiosis Ruminants Ruminants

Symbionts: koala-- enlarged cecum, symbiotic bacteria ferment finely shredded eucalyptus leaves.

Ruminants—4 stomach chambers—microbial action Well developed for vegetation: which include deer, cattle, and sheep.

(1) (1) Cow first chews and swallows a mouthful of grass (2) (2) boluses enter the rumen and (2) the reticulum. Symbiotic bacteria and protists digest this cellulose-rich meal, secreting fatty acids. Periodically, the cow regurgitates and rechews the cud, which further breaks down the cellulose fibers. (3) The cow then reswallows the cud, which moves to the omasum; water is removed. (4) The cud, with many microorganisms, passes to the abomasum for digestion by the cow’s enzymes. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

The length of the vertebrate digestive system is also correlated with diet. In general, herbivores and omnivores have longer alimentary canals relative to their body sizes than to carnivores, providing more time for digestion and more surface area for absorption of nutrients. Vegetation is more difficult to digest than meat because it contains cells walls. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

(1) Heterotrophic protists engulf their food by phagocytosis or pinocytosis and (2) digest their meals in food vacuoles. (3) Newly formed vacuoles are carried around the cell (4) until they fuse with lysosomes, which are organelles containing hydrolytic enzymes. (5) Later, the vacuole fuses with an anal pore and its contents are eliminated. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig