Nutrition & Metabolism PDF

1 NUTRITION & METABOLOMICS Dr. Samantha Solecki, DC, MS Instructor, Biology Thinker. Learner. Motivator. Lover of Anatomy & Physiology [email protected] © 2019 Pearson Education, Inc. ...

1 NUTRITION & METABOLOMICS Dr. Samantha Solecki, DC, MS Instructor, Biology Thinker. Learner. Motivator. Lover of Anatomy & Physiology [email protected] © 2019 Pearson Education, Inc.  2 Learning Objectives *Acquired from the Human Anatomy and Physiology Society (HAPS) with personal additions With respect to nutrients: Define nutrient, essential nutrient and non-essential nutrient. List the six main classes of nutrients. Classify vitamins as either fat-soluble or water-soluble and discuss the major uses of each vitamin in the body. List the important dietary minerals and describe the major uses of each mineral in the body. Describe the components of a balanced diet including the concept of recommended daily amounts. Define metabolism, anabolism and catabolism. Provide examples of anabolic and catabolic reactions. Compare and contrast the roles of enzymes and coenzymes in metabolism. With respect to carbohydrate metabolism: State the overall reaction for glucose metabolism. Describe the processes of glycolysis, formation of acetyl CoA, the Kreb’s cycle and the electron transport chain. Describe the role of the liver in metabolism. Compare and contrast the processes that occur in the absorptive and post-absorptive states. Define metabolic rate and basal metabolic rate. Provide specific examples to demonstrate how metabolic processes respond to maintain homeostasis in the body.  3 Nutrients Most nutrients are used for metabolic fuel, but some are for cell structures and molecular synthesis Nutrient: substance in food needed for growth, maintenance, repair Macronutrients: three major nutrients that make up the bulk of ingested food Carbohydrates, lipids, and proteins  4 Nutrients Micronutrients: two other nutrients that are required, but only in small amounts Vitamins and minerals Water is required, so technically it is a nutrient Essential nutrients: nutrients that must be eaten because body cannot synthesize these from other nutrients 45–50 nutrients are considered essential  5 Nutrients Nonessential nutrients are also vital to life, but if not enough is available, liver can usually convert another nutrient into one needed Energy value is measured in kilocalories (kcal) A calorie is the amount of heat needed to raise temperature of 1 kg H2O by 1oC One dietary “Calorie” equals 1 kcal  6 Macromolecules 1. Carbohydrates Monosaccharides, Disaccharides, Oligosaccharides, Polysaccharides Starch, Cellulose, Glycogen Simple versus Complex 2. Proteins Amino acids, dipeptides, tripeptides, polypeptides, protein Fibrous versus Globular Complete versus incomplete 3. Lipids Monoglycerides, Diglycerides, Triglycerides, Cholesterol Saturated fatty acids versus Unsaturated fatty acids 4. Nucleic Acids  7 Carbohydrates Dietary sources Primarily from plants, such as starch (complex carbohydrates) in grains and vegetables Sugars (mono- and disaccharides) in fruits, sugarcane, sugar beets, honey, and milk Insoluble fiber: cellulose in vegetables provides roughage Soluble fiber: pectin in apples and citrus fruits reduces blood cholesterol levels Small amount in milk sugar, glycogen in meats  8 Carbohydrates Uses in body Glucose: fuel most used by cells to make ATP Some cells use fat for energy Neurons and RBCs rely entirely on glucose Neurons die quickly without glucose Excess glucose is converted to glycogen or fat, then stored Fructose and galactose are converted to glucose by liver before entering circulation  9 Lipids Dietary sources Triglycerides (neutral fats): most abundant form Found in saturated fats in meat, dairy foods, tropical oils, or hydrogenated oils (trans fats) Unsaturated fats found in seeds, nuts, olive oil, and most vegetable oils Cholesterol found in egg yolk, meats, organ meats, shellfish, and milk products Liver makes ~85% cholesterol  10 Lipids Liver can convert some fatty acids into others, Two essential fatty acids it cannot synthesize: Linoleic acid – an omega-6 fatty acid Component of lecithin Linolenic acid – an omega-3 fatty acid Both can be found in most vegetable oils  11 Lipids Uses in body Adipose tissue offers protection, insulation, fuel storage Phospholipids essential in myelin sheaths and all cell membranes Cholesterol stabilizes membranes; precursor of bile salts, steroid hormones Prostaglandins smooth muscle contraction, BP control, inflammation Major fuel of hepatocytes and skeletal muscle Help absorb fat-soluble vitamins  12 Cholesterol Function: Low-density lipoprotein Very low-density lipoprotein High-density lipoprotein  13 Composition and Function of Lipoproteins Figure 24.24 Composition and function of lipoproteins  14 Proteins Dietary sources Animal products (eggs, milk, fish, most meats), as well as soybeans, are considered complete proteins Contain all needed essential amino acids Legumes, nuts, and cereals contain incomplete proteins (lack some essential amino acids) Legumes and cereal grains together contain all essential amino acids  15 Essential Amino Acids Figure 24.2 Essential amino acids  16 Proteins Uses in body Structural materials Example: keratin (skin), collagen and elastin (connective tissue), and muscle proteins Functional molecules Example: enzymes and some hormones Three factors help determine whether amino acids are used to synthesize proteins or burned as fuel: 1. All-or-none rule All amino acids needed must be present for protein synthesis to occur; if not all are present, then amino acids are used for energy  17 Proteins Uses in body (cont.) 2. Adequacy of caloric intake Protein is used as fuel if insufficient carbohydrate or fat is available 3. Hormonal controls Anabolic hormones (GH, sex hormones) accelerate protein synthesis and growth Adrenal glucocorticoids (released during stress) promote protein breakdown and conversion of amino acids to glucose  18 Proteins Uses in body (cont.) Nitrogen balance Homeostatic state where rate of protein synthesis equals rate of breakdown and loss Positive nitrogen balance: synthesis exceeds breakdown (normal in children, pregnant women, tissue repair) Negative nitrogen balance: breakdown exceeds synthesis (example: stress, burns, infection, injury, poor dietary proteins, starvation)  19 Cofactors/Coenzymes Vitamins Fat-soluble vitamins A, D, E, K Water-soluble vitamins C & B-vitamins Minerals Sodium, chloride, potassium, iodine, magnesium, manganese...  20 Vitamins Dangerous free radicals are generated during normal metabolism Vitamins C, E, and A and mineral selenium are antioxidants that neutralize these free radicals Broccoli, cauliflower, brussels sprouts are all good sources of vitamins A and C Megadoses*** of vitamins are useless and may actually cause serious health problems, depending on vitamin involved  21 Vitamins Table 24.2 Vitamins  22 Minerals Table 24.3 Minerals in the Body  23 METABOLISM  24 Absorptive & Postabsorptive States Absorptive State Fed/Following a meal Anabolism >>> Catabolism Hormones involved: Postabsorptive State Fasting/Hours after a meal Catabolism >>> Anabolism Hormones involved:  25 Principles of Metabolism Cellular metabolism --- Adenosine Triphosphate (ATP) Glycolysis Tricarboxylic Acid Cycle Electron Transport Chain Oxidation : loss of electrons (loss of energy) Reduction : gain of electrons (gain energy) Anabolism Catabolism  26 Anabolism and Catabolism Cellular respiration: catabolic breakdown of food fuels whereby energy from food is captured to form ATP in cells Goal of cellular respiration is to trap chemical energy in ATP Energy can also be stored in glycogen and fats, which can be broken down later Phosphorylation: enzymes shift high-energy phosphate groups of ATP to other molecules Phosphorylated molecules become activated to perform cellular functions  27 Anabolism and Catabolism Three stages in processing nutrients Stage 1: Digestion, absorption, and transport to tissues Stage 2: Cellular processing (in cytoplasm) Synthesis of lipids, proteins, and glycogen, or Catabolism (glycolysis) into pyruvic acid and acetyl CoA Stage 3: Oxidative breakdown of intermediates into CO2, water, and ATP Occurs in mitochondria Cellular respiration consists of glycolysis of stage 2 and all of stage 3  28 Three Stages of Metabolism of Energy-Containing Nutrients Figure 24.3 Three stages of metabolism of energy-containing nutrients Interconversion of 29 Carbohydrates, Fats, and Proteins Figure 24.19 Interconversion of carbohydrates, fats, and proteins  30 Metabolic Roles of Organs... Stomach Small Intestine Large Intestine Liver Gallbladder Pancreas  31 Energy Balance Energy intake versus Energy expenditure Waist:Hip Fat deposition Body Mass Index BMI = wt (lbs) x 705 / ht (in)2 20-24.9 25-29.9 30-34.9 35-39.9 40+  32 Metabolic Rate Total heat produced by chemical reactions and mechanical work of the body Basal metabolic rate (BMR) energy needed to perform essential activities Depends on body surface area, gender, age, hormones, and stress Doesn’t vary with physical training Total metabolic rate (TMR) Rate of kilocalorie consumption to fuel all ongoing activities Increases with skeletal muscle activity and food ingestion  33 Neurological and Hormonal Influences of Food Intake Hypothalamus Regulating hunger and satiety Short-term controls Neural: content of food and stretch Nutrient levels: glucose, amino acids, fatty acids Hormonal: insulin & CCK stop hunger; glucagon, epinephrine and ghrelin stimulate hunger Long-term controls Leptin from adipose cells; rising levels suppress appetite to a point  34 Disorders of Nutrition Obesity Metabolic Syndrome Type 2 Diabetes Mellitus Malnutrition