Chapter 41 Animal Nutrition Nutrition food taken in broken apart and taken up Herbivores eat plants algae Carnivores eat other animals Carnivores eat other animals Omnivores eat both animals and plants Animals diet must supply chemical energy organic molecules and essential nutrients Chemical energy used to make ATP 2 organic molecules needed o Organic carbon sugar o Organic nitrogen protein Essential nutrients minerals required but not made by cells o Some universal some specific to the animal 4 classes of essential nutrients o Essential amino acids amino acids that cannot be synthesized by animals and must be eaten Most animals need 8 Complete protein provide all essential amino acids meet and cheese Incomplete protein missing 1 or more essential amino acids plants o Essential fatty acids fatty acids with one or more double bonds and are o Vitamins organic molecules with diverse functions and are required in small unsaturated Ex linoleic acids amounts Water soluble often coenzymes Fat soluble A visual pigments of the eye D calcium absorption K blood clotting Iodine used by vertebrates to make thyroid hormone to regulate metabolic rate o Minerals inorganic nutrients required in small amounts Cofactors built into enzyme Na K and Cl used to maintain osmotic balance Ca and P for bone building and maintenance Dietary deficiencies o Malnutrition failure to obtain adequate nutrition o Deficiencies in essential nutrients Herbivores might have fragile bones if they lack P o Undernutrition diet that fails to provide adequate sources of chemical energy Body uses up stores of fat and carbs then starts to break down muscles brain might eventually become protein deficient Will eventually die Assessing nutritional needs o Hard to tell what humans really need Genetically divers Far from lab purity to study Ethical concerns Epidemiology study of human health and disease at the population level Main stages of food processing ingestion digestion absorption and elimination Ingestion act of eating feeding 4 main functions of the digestive system o Process food o Absorption of nutrients from food organics o Absorption of electroyltes inorganics o Absorption of water Digestion food is broken down in to molecules small enough to be absorbed o Mechanical chewing increases surface area o Chemical breaks down macromolecules so they can pass through membrane and be reassembled into macromolecules needed o Enzymatic hydrolysis opposite of building of macromolecules Breaks bonds by adding water Polysaccharides into simple sugars Proteins into amino acids Nucleic acids into nucleotides Fatty acids and components from fats phospholipids Absorption cells absorb small molecules Elimination undigested material leaves digestive system Digestive compartments o Intracellular digestion hydrolysis of food inside vacuoles Cell engulfs solid food by phagocytosis or liquid by pinocytosis Vacuoles fuse with lysosomes with hydrolytic enzymes Primitive animals hydra o Extracellular digestion breakdown of food in compartments that are continuous with the outside of the animals body Animal can eat larger pieces of food that cannot be eaten by phagocytosis Gastrovascular cavity digestive cavity with 1 opening used in digestion and distribution of nutrients in the body Flatworms and cnidarians Alimentary canal digestive tube that runs between mouth and anus complete digestive tract Can eat while previous meals are being digested Organs Specialized for Sequential Stages of Food Processing form the Mammalian Digestive System Alimentary canal and accessory glands o Peristalsis alternating waves of contraction and relaxation in smooth muscles that pushes food through the alimentary canal o Sphincters rings of muscles that regulate the passage of materials Oral cavity pharynx and esophagus o Oral cavity mouth Teeth grind food to make it easier to swallow and increase surface area o Salivary glands secrete saliva to start chemical digestion and protect the oral cavity Ptyalin hydrolyzes starch and glycogen into smaller polysaccharides and o Mucous viscous mixture of water salts cells and glycoproteins Protects lining of mouth from abrasion and makes swallowing easier Also has buffers neutralizes acids to prevent tooth decay antimicrobial agents maltose lysozyme to protect against bacteria o Tongue evaluates food and helps with swallowing o Bolus ball of food o Pharynx throat region opens to trachea and esophagus o Epiglottis covers the glottis vocal cords o Esophagus connects to the stomach Made of smooth peristalsis and striated muscle near the top Digestion in the stomach o Gastroesophageal GE sphincter upper end of stomach o Pyloric sphincter lower end of stomach to small intestine o 2 components of gastric juice bacteria too HCl pH of 2 breaks down meat and plant ECM and denatures proteins kills Protease protein digesting enzyme breaks proteins into smaller polypeptides o Gastric juice is kept inactive until it is released into the lumen of the stomach Made in gastric glands in gastric pits Parietal cells secrete H and Cl that make HCl Chief cells release inactive form of pepsin pepsinogen which is converted to pepsin by HCl by exposing the active site pepsin itself helps activate pepsinogen o Positive feedback o Stomach lining secretes mucus to protect from self digestion New layer of epithelia every 3 days o Stomach dynamics Stomach mixes contents every 20 seconds Pass to small intestine 2 6 hours after a meal Digestion in the small intestine mostly enzymatic hydrolysis o Small intestine largest compartment with small diameter Duodenum 1st 10 inches of small intestine where chyme from stomach mixes with juices from the pancreas liver and gallbladder Secrees alkaline mucus to bring pH to 7 5 7 8 Stomach an duodenum hormones control digestive secretions o Cholecystokinin and secretin tell pancreas to secrete digestive enymes and liver to make bile o Enterogastrone shuts down stomach Pancreas makes alkaline solution rich in o Bicarbonate neutralizes chyme and acts as a buffer o Enzymes inactive trypsin and chymotrypsin to be activated in duodenum Liver makes bile o Bile salts that act as emulsifiers digestion and absorption of lipids Includes blood pigments left when the liver breaks down old blood cells Neutralizes acid o Gallbladder stores and concentrates bile Crypts of lieberkuhn glandular structures that secrete more enzymes Jejunum and ileum function mainly in water and nutrient absorption Absorption in the small
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