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Bioenergetics and Digestion

Bioenergetics and Digestion. We’ll be discussing. Trends and Various Strategies Used by Organisms to Process Food Process of Digestion in Man Disorders of the Human Digestive System. Core Concepts. Nutritional requirements

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Bioenergetics and Digestion

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  1. Bioenergetics and Digestion

  2. We’ll be discussing • Trends and Various Strategies Used by Organisms to Process Food • Process of Digestion in Man • Disorders of the Human Digestive System

  3. Core Concepts • Nutritional requirements • Animals are heterotrophs that require food for fuel, carbon skeletons, and essential nutrients. • Metabolic rate provides clues to an animal’s bioenergetic strategy. •  Evolutionary adaptations of feeding mechanisms and digestive systems • Diverse feeding adaptations have evolved among animals. • Structural adaptations of digestive systems are often associated with diet. • Symbiotic microorganisms help nourish many vertebrates. • Overview of food processing • The four main stages of food processing are ingestion, digestion, absorption, and elimination. • Digestion occurs in specialized compartments. • The oral cavity, pharynx, and esophagus initiate food processing. • The stomach stores food and performs preliminary digestion. • The small intestine is the major organ of digestion and absorption. • Reclaiming water is a major function of the large intestine. • Hormones regulate digestion. • Reclaiming water is a major function of the large intestine. • Nutrition and disorders of the human digestive system • A healthful diet provides both fuel and building materials. • Nutritional disorders damage health.

  4. Keywords • minerals • nutrition • obesity • pancreas • peristalsis • peptic ulcers • peristalsis • phagocytosis • pharynx • salivary glands • small intestine • sphincters • stomach • undernutrition • vesicles • villus • vitamins • essential nutrient • extracellular digestion • filter feeders • gallbladder • gastrovascular cavity • gizzard • heterotroph • ileum • incomplete digestive tract • ingestion • intracellular digestion • jejunum • large intestine • liver • malnutrition • microvilli • absorption • alimentary canal • amebocytes • anorexia • bile • bolus • brush border • bulimia • cecum • chyme • complete digestive tract • crop • digestion • duodenum • elimination • endocytosis • enzyme • esophagus

  5. Bioenergetics of an animal Food Fuel C-skeletons essential nutrients ATP powers resting metabolism, activity, and temperature regulation Excess calories can be used for biosynthesis 85-90% of energy from food is lost as heat

  6. Metabolic rates • Metabolism • Anabolism • Catabolism • Resting/ Basal Metabolic Rate (BMR) • energy/unit mass/hr • Size and relative metabolic rate are inversely proportional

  7. Do plants have digestive systems? • Carnivorous plants in marshlands have primitive digestive systems • Habitats with N-poor soils • Adaptation: occasionally feed on animals CH2O  Photosynthesis N+ minerals  insects, etc. Flypaper trap – Pinguicula gigantea Pitcher plant – Heliamphora nutans Venus fly trap– Dionaea muscipula Sundew– Drosera capensis

  8. Evolution of digestion • Different types depending on diet and lifestyle • All must accomplish • Ingestion • Digestion • Mechanical breakdown • Chemical breakdown • Absorption • Elimination • Digestion occurs in specialized compartments

  9. Intracellular digestion ( 1 ) (evolved in single-celled protists, retained in simplest animals) Protists Paramecium

  10. Intracellular digestion ( 2 ) (evolved in single-celled protists, retained in simplest animals) SPONGES

  11. Extracellular digestion ( by fungi ) Fungi • Sedentary heterotrophs living in or on food supply • Saprotroph/parasites • No internal cavity  release digestive enzymes Image from http://www.aber.ac.uk/fungi/graffeg/decomp/digestion-by-hypha.jpg

  12. Extracellular and intracellular digestion1. In animals with incomplete digestive systems (1) Cnidarians Hydra Image from http://www.anselm.edu/homepage/jpitocch/genbio/digesthydra.jpg

  13. Extracellular and intracellular digestion 1. In animals with incomplete digestive systems (2) Platyhelminthes Planaria and tapeworms

  14. Extracellular digestion 2. In animals with complete digestive systems Nematoda to Vertebrates Earthworms • 20 cm long with ~ 100 segments • 1st – mouth • Last – anus • Eats its way through soil

  15. Feeding adaptations for ingestion

  16. Comparison of vertebrate digestive systems

  17. Mammalian digestion General plan Organs of the GI tract Accessory digestive organs

  18. Comparison of mammalian digestive systems(Diet plays an important role in the length and structure)

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