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Understanding Nutrition: Essentials for a Healthy Life

Learn about nutrients, carbohydrates, lipids, proteins, vitamins, minerals, and their functions. Discover the importance of essential nutrients and how they support your body's functioning. Dive into the world of metabolism and how your body processes nutrients for energy and essential functions.

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Understanding Nutrition: Essentials for a Healthy Life

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  1. Body Functioning Chapter 24

  2. Nutrition

  3. Nutrients • Substances to promote/enable life • Categories • Major nutrients (carbs, lipids, and proteins) • Vitamins and minerals • Water • Essential nutrients can’t be made ourselves

  4. Carbohydrates • Primarily from plants • Complex carbohydrates (e.gpolysaccharides or starches) • Bread, cereal, pasta, vegetables, potatoes • Simple carbohydrates (e.gmonosaccharides or sugars) • Pop, candy, fruit, ice cream, fruits • Glucose is basic form and fuel source (4kcal/g) • Excess stored as glycogen and fat • 45 – 60% daily calories recommended • Protein and fat used when less

  5. Lipids • Triglycerides (fats) • Unsaturated (vegetable fats/oils) and saturated (animal fats/solids) • Protect, cushion, insulate, and fuel source (9kcal/g) • Cholesterol • Egg yolk, meat, shellfish, milk products • Stabilizes PM and precursor for steroid hormones and bile salts • Essential fatty acids (linoleic and linolenic acids) • Found in most vegetable oils • Prostaglandin production • 20 – 35% daily calories

  6. Proteins • Complete (animal products) • Eggs, milk, fish, meats • Have all essential AA’s for maintenance and growth • Incomplete (plant products) • Legumes, seeds, vegetables, grains • Lack 1 or more AA’s • Vegetarian diets and rice w/bean diets • Structural materials • Keratin, collagen, elastin, muscle fibers • Functional uses • Enzymes, hormones, hemoglobin • 12 – 20 % daily calories

  7. Protein Use Determination • All-or-none rule • AA’s not stored • Protein synthesis requires all AA’s needed present • Caloric intake • Fuel (4kcal/g) w/ insufficient carbs or fats • Nitrogen balance • Ingestion = excretion • Positive w/ synthesis > breakdown (growth & repair) • Negative w/ breakdown > synthesis (starvation & injury) • Hormones • Anabolic hormones (GH & sex hormones) accelerate synthesis • Stress (glucocorticoids) accelerate breakdown

  8. Vitamins • Organic molecules needed in small amounts • Water soluble, • B-complex and C absorbed in GI tract w/water • B12 needs intrinsic factor from stomach • Fat soluble • Vitamins A, D, E, and K absorbed in GI tract w/ source • Obtained in most foods • Coenzymes in the body • Most are essential • Vitamin D (skin) and K (intestines) are exceptions • Table 24.2

  9. Minerals • Inorganic molecules needed by the body • Major needed in moderate amounts • Ca2+, phosphorus, K+, sulfur, Na+, Cl-, Mg2+ • Minor needed in trace amounts • Iron, iodine, fluorine, zinc • Vegetables, legumes, milk, and meats = good • Refined cereals, fats, sugars, and grains = poor • Ca2+, phosphate, and Mg2 harden bone • Na+ and Cl- for nerve and muscle fxnand H2O balance • Table 24.3

  10. Metabolism

  11. Metabolism (review) • All chemical reactions necessary for life • Reaction types • Anabolic: build up/synthesis • AA + AA + …  polypeptide • Catabolic: break down/hydrolyze • Starch  glucose + glucose + … • Cellular respiration (glucose catabolism) • Redox reactions • Oxidation: lose electron/energy* (LEO) by dehydrogenase • Reduction: gain electron/energy* (GER) by oxidases • Phosphorylation • Addition of a phosphate group (PO3-) to activate • ADP + P ATP • Substrate-level or oxidative

  12. Metabolizing Nutrients (overview) • Stage 1 • Digestion and absorption in GI tract • Stage 2 • Anabolic and/or catabolic processing in tissues • Glycoysis • Stage 3 • Stage 2 products catabolized in mitochondria • Kreb’s cycle and oxidative phosphorylation • Fig 24.3

  13. Glucose Catabolism (overview) • Aerobic use of primary fuel source • Overall reaction C6H12O6 + 6O26H2O + 6CO2 + 36-38 ATP + heat • Overall process • Glycolysis (cytoplasm) • Glucose  pyruvate + NADH + 2 (net) ATP • Kreb’s Cycle (mitochondria) • Pyruvate  CO2 + NADH + FADH2 + 2 ATP • Oxidative phosphorylation (mitochondria) • ETC and chemiosmosis • NADH + FADH2 + O2 H2O + 36 -38 ATP • Fig 24.5

  14. Glycolysis • Aerobic or anaerobic conditions • In the cytoplasm • Starts with: • Glucose (6C’s) • 2 ATP • Ends with: • 2 pyruvate (3C’s) or • Lactic acid or CO2 and EtOH • Important products of this process: • Net 2 ATP • 4 ATP  substrate-level phosphorylation • 2 NADH

  15. Transition • Cytoplasm to mitochondria • Starts with: • 2 Pyruvate (3C’s) • Ends with: • 2 Acetyl-CoA (2C’s) • Important products of this process: • 2 CO2 Decarboxylation • 2 NADH

  16. Kreb’sCycle • In the mitochondrial matrix CYCLE SEEN OCCURS TWICE • Starts with: • 2 Acetyl CoA • Ends with: • 4 CO2 • Important products of this process: • 2 ATP  substrate level phosphorylation • 6 NADH • 2 FADH2 6 C’s 4 C’s 4 C’s

  17. Oxidative Phosphorylation: Electron Transport Chain (ETC) • In the inner mitochondrial membrane (cristae) • Starts with: • 10 NADH (2 glycolysis, 2 transition, and 4 Kreb’s cycle) • 2 FADH2 (citric acid cycle) • 6 O2 (final e- acceptor) • Ends with: • H2O • Important products of this process: • H + gradient

  18. Oxidative Phosphorylation: Chemiosmosis • In the inner mitochondrial membrane (cristae) • Starts with: • H + gradient • Ends with: • 32 – 34 ATP • ATP synthase facilitates

  19. A Review of Glucose Catabolism Substrate level phosphorylation

  20. Regulating Glucose Levels • High glucose and/or lots of ATP inhibits glucose catabolism • Body unable to store ATP • Glucose converted to glycogen for storage • In liver and skeletal muscle storage = glycogenesis • Drop in glucose signals glycogenolysis • Glycogen (liver) catabolized to glucose • Low glucose levels signal gluconeogenesis • New glucose from non-carbs (fat and protein) in liver

  21. Lipid Catabolism • Triglycerides from GI tract, as chylomicrons (soluble lipids) • Glycerol pathway • Glycerol  glycolysis intermediate  glucose catabolism (glycolysis start) • ½ glucose molecule ~ 16 ATP • Fatty acid pathway • FA’s  acetic acid  glucose catabolism (Kreb’s start) • FA’s  NADH and FADH2 • More compact energy source w/ 2X’s more PE

  22. Lipids and Adipose Tissue • High ATP and glucose stimulates lipogenesis • Synthesis of triglycerides for liver & adipose storage • High ATP = excess glycolysis intermediates • Converted into lipogenesis pathway • Excess carbs, but low fat diet = fat storage • Glucose deficiency stimulates lipolysis (liver, cardiac & skeletal muscle) • Breakdown of stored fat • Severe depletion causes ketogenesis • Incomplete breakdown of fats produce ketones • Lowers blood pH causing ketosis

  23. Protein Metabolism • Protein catabolism oxidizes AA’s for energy • Transamination: NH2 (amine) to Kreb’s intermediate • Liver uses for non-essential AA synthesis • Oxidative deamination: NH2 removed as NH3 (ammonia) • Combine w/ CO2 (liver) to detoxify = urea and H2O • Keto acid modification: alters intermediate for Kreb’s entry • Protein anabolism or fat storage • All-or-none rule (earlier) • Otherwise become energy fuels

  24. Energy Regulation

  25. Heat Exchange • From variations between skin and external environment • Types • Radiation • Heat transfer b/w 2 objects not in contact w/ each other • Body heat in rooms or sunbathing • Conduction • Heat transfer b/w 2 objects in contact w/each other • Entering a hot tub or sitting in a seat • Convection • Heat transfer b/c density (heat rises = less dense) • Fan direction in summer (air up) vs winter (air down) • Evaporation • Heat transfer b/c H2O molecules evaporate • Sweating

  26. Heat Production • From low temps. in external environment or blood • Mechanisms • Vasoconstriction: reduces superficial blood flow to reduce shell loss • Frostbite when extended from decreased O2 and nutrients • Shivering: involuntary relax/contract of muscles • Metabolic increase: Epi and NE release increased • Increased thyroxine release: increases metabolic rate • Behavioral changes: add layers/blankets, drinkhot beverages, increase activity levels • Hypothermia when sluggish enzymes decreasing mechanisms

  27. Heat Loss • From high internal temps • Mechanisms • Types of heat exchange (previous) • Vasodilation: inhances superficial blood flow to increase shell loss • Sweating: perspiration to enhance evaporation • Ineffective w/ high humidity (the South) • Behavioral: finding shady spots/fans, reduce activity, looser/lighter/less clothing • Hyperthermia depresses hypothalamus (control) • Positive feedback mechanisms can cause heat stroke when mechanisms fail otherwise = heat exhaustion

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