Transcript Chapter 25
Anatomy and Physiology, Sixth Edition Rod R. Seeley Idaho State University Trent D. Stephens Idaho State University Philip Tate Phoenix College Chapter 25 Lecture Outline* *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. 25-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 25 Nutrition, Metabolism, Temperature Regulation 25-2 Nutrients • Chemicals used by body • Classes – Carbohydrates, proteins, lipids, vitamins, minerals, water • Food Guide Pyramid – USDA recommends • Kilocalories – Measure of energy supplied by food and released through metabolism 25-3 Carbohydrates • Monosaccharides – Include glucose, fructose, galactose • Disaccharides – Include sucrose, maltose, lactose • Polysaccharides (complex) – Include starch, glycogen, cellulose • Disaccharides and Polysaccharides – Converted to glucose (used for energy or stored as glycogen or fats) 25-4 Lipids • Triglycerides (95%): Used for energy to produce ATP or stored in adipose tissue, liver – Saturated fats: Meat fats, whole milk, cheese, eggs – Unsaturated fats: Olive and peanut oil • Cholesterol: Steroid found in liver, egg yolks but not found in plants • Phospholipids: Major components of plasma membranes 25-5 Proteins • Chains of amino acids – Kinds • Essential: Must be obtained in diet • Nonessential: Body can synthesize • Functions – Protection (antibodies), regulation (enzymes, hormones), structure (collagen), muscle contraction (actin, myosin), transportation (hemoglobin, ion channels) 25-6 Recommended Amounts • Carbohydrates – 60% of daily intake of kilocalories • Lipids – 30% or less of total daily kilocalories • Proteins – 10% of total kilocalories per day 25-7 Vitamins • Function as coenzymes or parts of coenzymes • Organic molecules that exist in minute quantities in food – Essential vitamins must be obtained by diet • Classifications – Fat soluble: Vitamins A,D,E,K – Water-soluble: B and C 25-8 Minerals • Inorganic • Necessary for normal metabolic functions • Functions – Establish resting membrane potentials, generate action potentials, add strength to bones and teeth, buffers, involved in osmotic balance • Obtained from animal and plant sources 25-9 Metabolism • Total of all chemical changes that occur in body – Anabolism: Energy-requiring process where small molecules joined to form larger molecules – Catabolism: Energy-releasing process where large molecules broken down to smaller • Energy in carbohydrates, lipids, proteins is used to produce ATP through oxidationreduction reactions 25-10 Catabolic and Anabolic Reactions 25-11 Cellular Metabolism 25-12 Carbohydrate Metabolism • Glycolysis – Breakdown of glucose into 2 pyruvic acid molecules • Phases – – – – Input of ATP Sugar cleavage NADH production ATP and pyruvic acid production 25-13 Glycolysis 25-14 Glycolysis 25-15 Anaerobic Respiration • Breakdown of glucose in absence of oxygen – Produces 2 molecules of lactic acid and 2 molecules of ATP • Phases – Glycolysis – Lactic acid formation • Cori cycle – Process of converting lactic acid to glucose 25-16 Aerobic Respiration • Breakdown of glucose in presence of oxygen to produce carbon dioxide, water, 38 ATP molecules – Most of ATP molecules to sustain life are produced this way • Phases – Glycolysis, acetyl-CoA formation, citric acid cycle, electron-transport chain 25-17 Aerobic Respiration 25-18 Electron-Transport Chain 25-19 Lipid Metabolism • Adipose triglycerides are broken down and released as free fatty acids • Free fatty acids are taken up by cells and broken down by beta-oxidation into acetyl-CoA which – Can enter citric acid cycle – Can be converted to ketone bodies 25-20 Protein Metabolism • New amino acids are formed by transamination, transfer of an amine group to keto acid • Amino acids are used to synthesize proteins – If used for energy, ammonia is produced as a by-product of oxidative deamination • Ammonia is converted to urea and excreted 25-21 Amino Acid Metabolism • Once absorbed in body, amino acids quickly taken up by cells • Amino acids are used to synthesize proteins or as a source of energy • Amino acids not stored in body 25-22 Amino Acid Reactions 25-23 Interconversion of Nutrient Molecules • Glycogenesis – Excess glucose used to form glycogen • Lipogenesis – When glycogen stores filled, glucose and amino acids used to synthesize lipids • Glycogenolysis – Breakdown of glycogen to glucose • Gluconeogenesis – Formation of glucose from amino acids and glycerol 25-24 Interconversion of Nutrient Molecules 25-25 Metabolic States • Absorptive state – Period immediately after eating when nutrients absorbed through intestinal wall into circulatory and lymphatic systems (about 4 hours after each meal) • Postabsorptive state – Occurs late in morning, afternoon, night after absorptive state concluded – Blood glucose levels maintained by conversion of other molecules to glucose 25-26 Absorptive State 25-27 Postabsorptive State 25-28 Metabolic Rate • Total amount of energy produced and used by body per unit of time – Estimated by amount of oxygen used per minute • Components – Basal metabolic rate • Energy used at rest, 60% of metabolic rate – Thermic effect of food • Energy used to digest and absorb food, 10% – Muscular activity • Energy used for muscle contraction, 30% 25-29 Body Temperature Regulation • A balance between heat gain and loss – Heat is produced through metabolism – Heat is exchanged through radiation, conduction, convection, evaporation • The greater the temperature difference between body and environment, the greater the rate of heat exchange • Regulated by a “set point” in hypothalamus 25-30 Heat Exchange 25-31 Temperature Regulation 25-32