Human Energy System

Human Energy System

Question Description

Chapter 6 Energy Balance 1 Human Energy System (1 of 2)  Energy needs ➢ Involuntary body work (greatest use of energy) ➢ Voluntary work and exercise  Measurement of energy ➢ Kilocalorie (kcal): amount of heat necessary to raise 1 kg of water 1° C ➢ Joule (J): international unit of measure for energy ➢ To convert kilocalories (kcal) into kilojoules (kJ): • Multiply the number of kilocalories by 4.184 2 Human Energy System (2 of 2)  Food as fuel for energy ➢ Adenosine triphosphate (ATP) • Metabolic end product of the energy-yielding foods consumed ➢ Fuel factors • Carbohydrate: 4 kcal/g; fat: 9 kcal/g; protein: 4 kcal/g; alcohol: 7 kcal/g ➢ Energy and nutrient density • Energy density: food with a high concentration of energy • Nutrient density: food with a high concentration of vitamins and minerals • Empty calorie foods: opposite of nutrient dense foods 3 Energy Balance (1 of 7)  Two energy systems support life ➢ External energy cycle: plants transform the sun’s radiation into stored energy ➢ Internal energy cycle: people eat plant and animal foods, and the stored energy of the food in its complex form is broken down into simple fuels and used, and eventually returned to the external environment 4 Energy Balance (2 of 7)  Energy intake ➢ Main source of energy: food and caloric drinks, supplemented by energy stored in body tissues ➢ Estimating dietary energy intake • Track intake and calculate energy value  Stored energy ➢ Glycogen: 12- to 48-hour reserve ➢ Adipose tissue: varies by individual ➢ Muscle mass: used only during longer periods of fasting or starvation 5 Energy Balance (3 of 7)  Energy Output ➢ Basal energy expenditure (BEE) • Sum of all internal activities of the body while at total rest ➢ Measuring BEE or resting energy expenditure (REE) • Direct calorimetry • Indirect calorimetry ➢ Predicting BEE or REE • Multiply 0.9 kcal/kg body weight for women and 1 kcal/kg body weight for men by the number of hours in a day ➢ Factors that influence basal energy expenditure • Influence from organs with high metabolic activity, body composition, growth periods, body temperature, hormonal status, and disease state 6 Energy Balance (4 of 7)  Energy Output ➢ Physical activity • Work, recreation, and activities of daily living ➢ Thermic effect of food • Energy required for the physical process of digestion, absorption, and transportation of nutrients to the cells ➢ Total energy expenditure (TEE) • Comprised of the energy needs for BEE, the physical activities of the person, and the thermic effects of food 7 Energy Balance (5 of 7) Courtesy Susie Parker-Simmons, United States Olympic Committee. 8 Energy Balance (6 of 7) Courtesy Microlife USA, Dunedin, FL. 9 Energy Balance (7 of 7) 10 Case Study (1 of 4)  Sara, a 35-year-old female, has an REE of 1500 kcal/d. She works 6 to 8 hours a day and usually takes a 2-mile walk after work. 11 Case Study (2 of 4)  What is the difference between REE and BEE? 12 Case Study (3 of 4)  Which organ systems use much of the body energy for cellular function? 13 Recommendations for Dietary Energy Intake (1 of 2)  General life cycle ➢ Growth periods • During periods of rapid growth, extra energy per unit of body weight is necessary to build new tissue. ➢ Adulthood • Energy needs decline with age but the specific amount of decline is highly individual. 14 Recommendations for Dietary Energy Intake (2 of 2)  Dietary Reference Intakes ➢ Note: DRIs for vitamins and minerals are set at two standard deviations above the mean in order to meet the needs of 97.5% of the population.  Dietary Guidelines for Americans ➢ Choose a healthy eating pattern at an appropriate calorie level ➢ Meet Physical Activity Guidelines for Americans  MyPlate ➢ Individualized plans 15 Chapter 4 Proteins 1 The Nature of Proteins (1 of 5)  Functions of amino acids ➢ Building blocks • Peptide bonds join amino acids together • Each protein chain adopts a folded form ➢ Dietary importance 2 The Nature of Proteins (2 of 5) Modified from Mahan LK, Escott-Stump S. Krause’s Food & Nutrition Therapy. 12th ed. Philadelphia: Saunders; 2008. 4 3 The Nature of Proteins (3 of 5)  Classes of amino acids ➢ Indispensable amino acids • Nine essential amino acids must be supplied in diet ➢ Dispensable amino acids • Five amino acids that the body can synthesize from other amino acids ➢ Conditionally indispensable amino acids • Six amino acids that can normally be synthesized by the body, but under certain conditions, must be supplied in diet 4 The Nature of Proteins (4 of 5)  Balance ➢ Protein balance • Catabolism • Anabolism • Deamination ➢ Nitrogen balance • Positive nitrogen balance • Negative nitrogen balance 5 The Nature of Proteins (5 of 5) 6 Functions of Proteins (1 of 2)  Primary tissue building ➢ Fundamental structural material of every cell ➢ Comprises bulk of muscles, internal organs, brain, nerves, skin, hair, and nails ➢ Vital component of enzymes, hormones, and blood plasma ➢ Protein repairs worn-out, wasted, or damaged tissue 7 Functions of Proteins (2 of 2)  Additional body functions ➢ Water and pH balance • Osmotic pressure ➢ Metabolism and transportation ➢ Immune system ➢ Energy system 8 Food Sources of Protein (1 of 2)  Types of dietary protein ➢ Complete proteins • Primarily of animal origin ➢ Incomplete proteins • Primarily of plant-origin 9 Food Sources of Protein (2 of 2)  Complementary protein ➢ Combining plant-protein foods to cover all amino acid needs and supply all indispensible amino acids  Types of vegetarian diets ➢ Lacto-vegetarian ➢ Ovo-vegetarian ➢ Lacto-ovo vegetarian ➢ Vegan 10 Digestion of Proteins Mouth  Stomach  ➢ Hydrochloric acid ➢ Pepsin ➢ Rennin  Small intestine ➢ Pancreatic secretions ➢ Intestinal secretions 11 Recommendations for Dietary Protein (1 of 2)  Influential factors of protein needs ➢ Tissue growth ➢ Dietary protein quality ➢ Additional needs caused by illness or disease 12 Recommendations for Dietary Protein (2 of 2)  Dietary deficiency or excess ➢ Protein energy malnutrition • Severe forms include:  Kwashiorkor  Marasmus ➢ Excess protein • Can displace other healthy foods in diet • The body deaminates extra protein so that it can store the carbon backbone as fat or use it as energy • Taking excessive single amino acid dietary supplements can be harmful if it creates an imbalance 13 Dietary Guides  Dietary Reference Intakes ➢ Recommended Dietary Allowances (RDAs)  Dietary Guidelines for Americans ➢ Choose a variety of protein foods ➢ Consume at least 8 oz per week of seafood from a variety of sources. ➢ Replace protein foods that are high in sodium and solid fat with more nutrient-dense options.  MyPlate ➢ Provides individualized plans 14