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Animal Nutrition (Ch. 41) http://www.youtube.com/watch?v=vJvfjiCTvq4 Examples: Some of the best known and fascinating adaptations of animals involve their feeding and digestion Python http://www.youtube.com/watch?v=aDW5HpdFals • Reptile swallowing prey • Baleen whales Starfish http://www.youtube.com/watch?v=i-EJuL0ix5Q www.youtube.com/watch?v=rE8l-KFQlhY Digestion in Paramecium Extracellular digestion Gastrovascular cavity: Hydra Gastrovascular cavity vs. Alimentary Canal • A. outside organism • B. gastrovascular cavities • C. alimentary canal Alimentary canal: a simple view Basic parts of alimentary canal Mechanical digestion storage absorption mouth anus Alimentary canal: mammalian Mouth Stomach • Mechanical • enzymatic Digestive mechanisms in stomach Stomach http://www.youtube .com/watch?v=umn nA50IDIY http://www.youtube .com/watch?v=Ln0 9qihUi3g http://www.youtube .com/watch?v=Uzl6 M1YlU3w • Mechanical • Chemical • enzymatic Digestive mechanisms in stomach • Mechanical • Chemical • enzymatic Mechanical • Mixing and churning Chemical • pH around 2 Enzymatic • Pepsin – Also breaks food down – Breaks down proteins Activation of pepsin Why doesn’t pepsin digest stomach? Small intestine • Most of the enzymatic digestion occurs here Why doesn’t the small intestine digest itself? Fig. 37.13 Most nutrient absorption takes place in small intestine • Structure: another example of increasing surface area Microvilli Structure of small intestine Large intestine (colon) • Major function is to reabsorb water Variations of vertebrate digestive system • Herbivorous mammals – Specialized fermentation chambers Why does herbivory require specializations? Coyote vs. Koala Structure of cellulose Campbell 6th ed p. 68 Horse cecum • Plant tissue – Harder to break up – Contains cellulose – Nutrients less concentrated than meat Campbell 6th ed p. 867 Cecum • Allows breakdown of cellulose in herbivores • One opening and exit - lower oxygen, slower passage • Digested cellulose must be reintroduced to digestive system Ruminant digestion Campbell 6th ed p. 868 Ruminant 4 chambered stomach Part of Campbell 6th ed p. 867 • Rumen and reticulum - where symbiotic bacteria and protists break down cellulose • Cow rechews food • Omasum - where water is absorbed • Abomasum - further digestion by cow’s enzymes http://www.youtube.com/watch?v=pbeI4aiSLyg Symbiosis Autotroph-invertebrate symbiosis • Symbionts are algae • Algae photosynthesize and provide molecules such as sugars to the host • Hydra, anemones, giant clams, corals Examples • • • • Sea anemone chloroplasts in plants coral reef corals (like anemone and green hydra) Examples http://www.youtube.com/watch?v=5d3qie3jbHk