Bio1A_sum07_lec8-8_slides6 - C h a p te r 4 1 A n im a l N...

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Chapter 41 Animal Nutrition Nutritional requirements Nutritional requirements mechanisms mechanisms Mammalian digestive system Mammalian digestive system Digestion and absorption Digestion and absorption Chapter 41 Animal Nutrition Nutritional requirements An adequate diet is required for: 1. Fuel 2. Biosynthesis 3. Essential nutrients Nutritional requirements Food for Fuel Fats are the richest in energy Oxidation of 1 gm: of fat produces 9.3 kcal of energy, of carbohydrate produces 4.1 kcal of energy, of protein produces 4.1 kcal of energy If an animal consumes excess calories: Glucose is 1. stored as glycogen in muscle and the liver (enough for 1 day BMR). 2. converted to lipids and stored as fat . Lipids are stored as fat . Proteins are converted to lipids and stored as fat . Most conversion occurs in the liver, and storage in adipose tissue. Between meals or if undernourished: 1. Glucose released from stored glycogen. 2. Net synthesis of glucose from lipids, and lastly from structural proteins = gluconeogenesis .
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3. Glucose sparing = with the exception of nervous tissue, tissues start using fatty acids for an energy source. Homeostatic regulation plasma glucose levels Increased plasma glucose above set point > increase insulin secretion. Insulin > •increased glucose uptake by cells •increase use of glucose for energy •increase storage of glucose as glycogen or fat > decreased plasma glucose. Homeostatic regulation plasma glucose levels Decreased plasma glucose below set point > increase glucagon secretion. Glucagon > •increased glycogen breakdown and gluconeogenesis in liver •decrease use of glucose for energy •increased use of free fatty acids for energy > increased plasma glucose. Food for Biosynthesis: Organic precursors for the fabrication of organic molecules: carbohydrates, proteins, and lipids. One amino acid can supply nitrogen for many other types of amino acids. Sugars are the source of carbon. Amino acids are the source of nitrogen. Food supplies essential nutrients . Substances the animal cannot fabricate from any precursor must be obtained from food. Malnourishment is a deficiency in one or more essential nutrient. Four classes of essential nutrients: Essential amino acids Essential fatty acids Vitamins Minerals Specifics vary from species to species. Essential amino acids
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Bio1A_sum07_lec8-8_slides6 - C h a p te r 4 1 A n im a l N...

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